- C-C Bond Cleavage of Acetonitrile by a Dinuclear Copper(II) Cryptate
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The dinuclear copper(II) cryptate [Cu2L](ClO4)4 (1) cleaves the C?C bond of acetonitrile at room temperature to produce a cyanide bridged complex of [Cu2L(CN)](ClO4)3·2CH3CN·4H2O (2). The cleavage mechanism is presented on the basis of the results of the crystal structure of 2, electronic absorption spectra, ESI-MS spectroscopy, and GC spectra of 1, respectively. Copyright
- Lu, Tongbu,Zhuang, Xiaomei,Li, Yanwu,Chen, Shi
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- Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4 catalyst under visible light irradiation
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An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4 as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a methanol yield of 2570.78 μmol per g cat after 48 h. This journal is
- Kumar, Pawan,Chauhan,Sain, Bir,Jain, Suman L.
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- CO2 Reduction Promoted by Imidazole Supported on a Phosphonium-Type Ionic-Liquid-Modified Au Electrode at a Low Overpotential
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The catalytic conversion of CO2 to useful compounds is of great importance from the viewpoint of global warming and development of alternatives to fossil fuels. Electrochemical reduction of CO2 using aromatic N-heterocylic molecules is a promising research area. We describe a high performance electrochemical system for reducing CO2 to formate, methanol, and CO using imidazole incorporated into a phosphonium-type ionic liquid-modified Au electrode, imidazole@IL/Au, at a low onset-potential of -0.32 V versus Ag/AgCl. This represents a significant improvement relative to the onset-potential obtained using a conventional Au electrode (-0.56 V). In the reduction carried out at -0.4 V, formate is mainly generated and methanol and CO are also generated with high efficiency at -0.6 ～ -0.8 V. The generation of methanol is confirmed by experiments using 13CO2 to generate 13CH3OH. To understand the reaction behavior of CO2 reduction, we characterized the reactions by conducting potential- and time-dependent in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements in D2O. During electrochemical CO2 reduction at -0.8 V, the C-O stretching band for CDOD (or COD) increases and the C=O stretching band for COOD increases at -0.4 V. These findings indicate that CO2 reduction intermediates, CDOD (or COD) and COOD, are formed, depending on the reduction potential, to convert CO2 to methanol and formate, respectively.
- Iijima, Go,Kitagawa, Tatsuya,Katayama, Akira,Inomata, Tomohiko,Yamaguchi, Hitoshi,Suzuki, Kazunori,Hirata, Kazuki,Hijikata, Yoshimasa,Ito, Miho,Masuda, Hideki
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- Photochemical and enzymatic synthesis of methanol from HCO3 - with dehydrogenases and zinc porphyrin
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Photochemical and enzymatic methanol synthesis from HCO3 - with formate dehydrogenase (FDH), aldehyde dehydrogenase (AldDH), and alcohol dehydrogenase (ADH) via the photoreduction of MV2+ using ZnTPPS photosensitization wa
- Amao, Yutaka,Watanabe, Tomoe
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- Catalytic Activity of Nanosized CuO-ZnO Supported on Titanium Chips in Hydrogenation of Carbon Dioxide to Methyl Alcohol
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In this study, titanium chips (TC) generated from industrial facilities was utilized as TiO2 support for hydrogenation of carbon dioxide (CO2) to methyl alcohol (CH3OH) over Cu-based catalysts. Nanosized CuO and ZnO catalysts were deposited on TiO2 support using a co-precipitation (CP) method (CuO-ZnO/TiO2), where the thermal treatment of TC and the particle size of TiO2 are optimized on CO2 conversion under different reaction temperature and contact time. Direct hydrogenation of CO2 to CH3OH over CuO-ZnO/TiO2 catalysts was achieved and the maximum selectivity (22%) and yield (18.2%) of CH3OH were obtained in the range of reaction temperature 210～240 °C under the 30 bar. The selectivity was readily increased by increasing the flow rate, which does not affect much to the CO2 conversion and CH3OH yield.
- Ahn, Ho-Geun,Lee, Hwan-Gyu,Chung, Min-Chul,Park, Kwon-Pil,Kim, Ki-Joong,Kang, Byeong-Mo,Jeong, Woon-Jo,Jung, Sang-Chul,Lee, Do-Jin
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- Photocatalytic conversion of carbon dioxide into methanol in reverse fuel cells with tungsten oxide and layered double hydroxide photocatalysts for solar fuel generation
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The phenomena of the photocatalytic oxidation of water and photocatalytic reduction of CO2 were combined using reverse photofuel cells, in which the two photocatalysts, WO3 and layered double hydroxide (LDH), were separated by a polymer electrolyte (PE) film. WO3 was used for the photooxidation of water, whereas LDH, comprising Zn, Cu, and Ga, was used for the photoreduction of CO2. For this process, photocatalysts pressed on both sides of the PE film were irradiated with UV-visible light through quartz windows and through the space in carbon electrode plates and water-repellent carbon paper for both gas flow and light transmission. 45% of the photocatalyst area was irradiated through the windows. The protons and electrons, which were formed on WO3 under the flow of helium and moisture, transferred to the LDH via the PE and external circuit, respectively. Methanol was the major product from the LDH under the flow of CO2 and helium. The observed photoreduction rates of CO2 to methanol accounted for 68%-100% of photocurrents. This supports the effectiveness of the combined photooxidation and photoreduction mechanism as a viable strategy to selectively produce methanol. In addition, we tested reverse photofuel cell-2, which consisted of a WO3 film pressed on C paper and LDH film pressed on Cu foil. The photoelectrodes were immersed in acidic solutions of pH 4, with the PE film distinguishing the two compartments. Both the photoelectrodes were completely irradiated by UV-visible light through the quartz windows. Consequently, the photocurrent from the LDH under CO2 flow to WO 3 under N2 flow was increased by 2.4-3.4 times in comparison to photofuel cell-1 tested under similar conditions. However, the major product from the LDH was H2 rather than methanol using photofuel cell-2. The photogenerated electrons in the irradiated area of the photocatalysts were obliged to diffuse laterally to the unirradiated area of photocatalysts in contact with the C papers in photofuel cell-1. This lateral diffusion reduced the photocatalytic conversion rates of CO2, despite the advantages of photofuel cell-1 in terms of selective formation and easy separation of gas-phase methanol. This journal is the Partner Organisations 2014.
- Morikawa, Motoharu,Ogura, Yuta,Ahmed, Naveed,Kawamura, Shogo,Mikami, Gaku,Okamoto, Seiji,Izumi, Yasuo
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- Comparative Study of Diverse Copper Zeolites for the Conversion of Methane into Methanol
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The characterization and reactive properties of copper zeolites with twelve framework topologies (MOR, EON, MAZ, MEI, BPH, FAU, LTL, MFI, HEU, FER, SZR, and CHA) are compared in the stepwise partial oxidation of methane into methanol. Cu2+ ion-exchanged zeolite omega, a MAZ-type material, reveals the highest yield (86 μmol g(cat.)?1) among these materials after high-temperature activation and liquid methanol extraction. The high yield is ascribed to the relatively high density of copper–oxo active species, which form in its three-dimensional 8-membered (MB) ring channels. In situ UV/Vis studies show that diverse copper species form in different zeolites after high-temperature activation, suggesting that there are no universally active species. Nonetheless, there are some dominant factors required for achieving high methanol yields: 1) highly dispersed copper–oxo species; 2) large amount of exchanged copper in small-pore zeolites; 3) moderately high temperature of activation; and 4) use of proton form zeolite precursors. Cu-omega and Cu-mordenite, with the proton form of mordenite as the precursor, yield methanol after activation in oxygen and reaction with methane at only 200 °C, that is, under isothermal conditions.
- Park, Min Bum,Ahn, Sang Hyun,Mansouri, Ali,Ranocchiari, Marco,van Bokhoven, Jeroen A.
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- Experimental measurements and kinetic modeling of CH4/O 2 and CH4/C2H6/02 conversion at high pressure
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A detailed chemical kinetic model for homogeneous combustion of the light hydrocarbon fuels CH4 and C2H6 in the intermediate temperature range roughly 500-1100 K, and pressures up to 100 bar has been developed and validated experimentally. Rate constants have been obtained from critical evaluation of data for individual elementary reactions reported in the literature with particular emphasis on the conditions relevant to the present work. The experiments, involving CH4/02 and CH4/C2H6/O2 mixtures diluted in N2 have been carried out in a high-pressure flow reactor at 600-900 K, 50-100 bar, and reaction stoichiometrics ranging from very lean to fuel-rich conditions. Model predictions are generally satisfactory. The governing reaction mechanisms are outlined based on calculations with the kinetic model. Finally, the mechanism was extended with a number of reactions important at high temperature and tested against data from shock tubes, laminar flames, and flow reactors.
- Rasmussen, Christian Lund,Geest Jakobsen,Glarborg, Peter
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- Cobalt phthalocyanine immobilized on graphene oxide: An efficient visible-active catalyst for the photoreduction of carbon dioxide
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New graphene oxide (GO)-tethered-CoII phthalocyanine complex [CoPc-GO] was synthesized by a stepwise procedure and demonstrated to be an efficient, cost-effective and recyclable photocatalyst for the reduction of carbon dioxide to produce methanol as the main product. The developed GO-immobilized CoPc was characterized by X-ray diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/Vis spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental analysis data showed that CoII-Pc complex was successfully grafted on GO. The prepared catalyst was used for the photocatalytic reduction of carbon dioxide by using water as a solvent and triethylamine as the sacrificial donor. Methanol was obtained as the major reaction product along with the formation of minor amount of CO (0.82%). It was found that GO-grafted CoPc exhibited higher photocatalytic activity than homogeneous CoPc, as well as GO, and showed good recoverability without significant leaching during the reaction. Quantitative determination of methanol was done by GC flame-ionization detector (FID), and verification of product was done by NMR spectroscopy. The yield of methanol after 48 h of reaction by using GO-CoPc catalyst in the presence of sacrificial donor triethylamine was found to be 3781.8881 μmolg-1cat., and the conversion rate was found to be 78.7893 μmolg-1cat.h-1. After the photoreduction experiment, the catalyst was easily recovered by filtration and reused for the subsequent recycling experiment without significant change in the catalytic efficiency. Very photoactive! Cobalt phthalocyanine grafted to the chemically functionalized graphene oxide was found to be an efficient heterogeneous visible-light-induced photoredox catalyst for the photoreduction of carbon dioxide to methanol in a very good yield. The developed photocatalyst exhibited superior activity compared with the existing photocatalytic systems and gave methanol as the major reaction product (see scheme).
- Kumar, Pawan,Kumar, Arvind,Sreedhar, Bojja,Sain, Bir,Ray, Siddharth S.,Jain, Suman L.
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- Facile synthesis of ZnO particles: Via benzene-assisted co-solvothermal method with different alcohols and its application
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In this study, ZnO particles with different morphologies were synthesized by a novel co-solvothermal method using benzene. The prepared samples were characterized by Brunauer-Emmett-Teller (BET) measurements, X-ray diffractometry (XRD), scanning electron microscopy coupled with an energy dispersive X-ray detector (SEM-EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectrometry (XPS), and H2-temperature programmed reduction (H2-TPR). The results showed that the molecular sizes and carbon numbers of the alcohols used in the reaction and the addition of benzene had a great effect on the morphologies, textural properties, and crystalline structures of the material products in our reaction system. Different ZnO morphologies, such as spherical coral-like, carnation-like, rose-like, and plate-like structures, were obtained using methanol, ethanol, propanol, and butanol, respectively. Moreover, Cu particles loaded on ZnO with different morphologies were also investigated for the hydrogenation of CO2 to CH3OH. High catalytic activity and selectivity (82.8%) for CH3OH formation were obtained using ZnO prepared from methanol with Cu doping (Cu/ZnO-Me).
- Maneechakr, Panya,Karnjanakom, Surachai,Samerjit, Jittima
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- Dynamics of Reaction of (meso-Tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato)iron(III) Hydrate with tert-Butyl Hydroperoxide in Aqueous Solution. 2. Establishment of a Mechanism That Involves Homolytic O-O Bond Breaking and One-Electron Oxidation of the Iron(III) Porphyrin
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The reaction of t-BuOOH with the water soluble and non-μ-oxo dimer forming (5,10,15,20-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato)iron(III) hydrate ((1)FeIII(X)(H2O) where X=H2O or HO(1-)) was studied in aqueous solution between pH 2 and 13 in the absence of an agent for the trapping of reaction intermediates.Products of t-BuOOH decomposition are (CH3)2CO (90percent), CH3OH (90percent), and t-BuOH (15percent), while neither CH4, C2H6, O2, nor (t-BuO)2 could be detected.That (CH3)2CO and CH3OH are formed through fragmentation of t-BuO. to (CH3)2CO and CH3. is shown by theobservation that the reaction of Ph(CH3)2COOH with (1)FeIII(X)(H2O) provides acetophenone but not phenol.This must be a consequence of homolytic O-O bond scission with the formation of Ph(CH3)2CO..The reaction of (1)FeIII(X)(H2O) with m-ClC6H4CO3H and the hydroperoxides t-BuOOH, Ph(CH3)2COOH, Ph2C(CO2CH3)OOH, and Ph2C(CN)OOH between pH 5 and 7 leads to the buildup of (1)FeIV(X)(H2O) species.The formation of an iron(IV)-oxo porphyrin species was established by titrimetric experiments as well as by carbon microelectrode voltommetry and 1e(1-) spectroelectrochemical generation of authentic (1)FeIV(X)(H2O) species.Formation of (1)FeIV(X)(H2O) species on oxidation of (1)FeIII(X)(H2O) with m-ClC6H4CO3H occurs in the absence of O2, while formation of (1)FeIV(X)(H2O) species on oxidation of (1)FeIII(X)(H2O) by the alkyl hydroperoxides, t-BuOOH and Ph(CH3)2COOH, requires the presence of O2.These observations require for the peracid a 2e(1-) oxidation with heterolytic O-O bond cleavage III(X)(H2O) --> m-ClC6H4CO2H + (+.1)FeIV(X)(H2O)> followed by a comproportionation reaction III(X)(H2O)+ (+.1)FeIV(X)(H2O) --> 2(1)FeIV(X)(H2O)>, while in the case of the reaction of the alkyl hydroperoxides a 1e(1-) oxidation occurs with homolytic O-O bond breaking.The fragmentation of the resultant t-BuO. provides (CH3)2CO and CH3., and reaction of the latter with (1)FeIII(X)(H2O) yields CH3OH and (1)FeII(X)(H2O).The resultant iron(II) porphyrin species reacts with O2 II(X)(H2O) + O2 --> 2(1)FeIV(X)(H2O)>.The putative (1)FeII(X)(H2O) intermediate was identified by its trapping with CO.Also, t-BuO. and CH3. intermediates were identified by their spin trapping with 5,5-dimethyl-1-pyrroline N-oxide.The rate constant for reaction of hydrogen peroxide with (1)FeIV(X)(H2O) exceeds that for other hydroperoxides investigated.Thus, (1)FeIV(X)(H2O) does not accumulate in the reaction of H2O2 with (1)FeIII(X)(H2O).The rapid reaction of H2O2 with (1)FeIV(X)(H2O) provides (1)FeIII(X)(H2O) and presumably O2.- + H(1+).This marks the first observation of the reaction of H2O2 with a compound II species.The pH dependence of the kinetics for the reaction of (1)FeIII(X)(H2O) with t-BuOOH has been determined and shown to be comparable to those of a previous study which...
- Balasubramanian, P. N.,Lindsay Smith, John R.,Davies, Michael J.,Kaaret, Thomas W.,Bruice, Thomas C.
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- Efficient ionic liquid-based platform for multi-enzymatic conversion of carbon dioxide to methanol
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Low yields commonly obtained during enzymatic conversion of CO2 to methanol are attributed to low CO2 solubility in water. In this study, four selected ionic liquids with high CO2 solubility were separately added to the multi-enzyme reaction mixture and the yields were compared to the pure aqueous system (control). In an aqueous 20% [CH][Glu] system, yield increased ca. 3.5-fold compared to the control (ca. 5-fold if NADH regeneration was incorporated). Molecular dynamics simulation revealed that CO2 remains for longer in a productive conformation in the enzyme in the presence of [CH][Glu], which explains the marked increase of yield that was also confirmed by isothermal titration calorimetry-lower energy (ΔG) binding of CO2 to FDH. The results suggest that the accessibility of CO2 to the enzyme active site depends on the absence/presence and nature of the ionic liquid, and that the enzyme conformation determines CO2 retention and hence final conversion.
- Zhang, Zhibo,Muschiol, Jan,Huang, Yuhong,Sigurdardóttir, Sigyn Bj?rk,Von Solms, Nicolas,Daugaard, Anders E.,Wei, Jiang,Luo, Jianquan,Xu, Bao-Hua,Zhang, Suojiang,Pinelo, Manuel
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- Development of highly stable catalyst for methanol synthesis from carbon dioxide
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Zr-doped Cu-Zn-Zr-Al (CZZA) catalyst showed excellent performances for the methanol synthesis from carbon dioxide and hydrogen such as activity, selectivity and especially stability under mild conditions (such as 230 C and 3.0 MPa). The catalyst showed excellent tolerance against water vapor. It was found that added alumina promoted the dispersion of Cu whereas it suppressed the reduction of copper oxide. On the other hand, added Zr promoted the catalytic activity of methanol synthesis from CO2 and suppressed the inhibitive effect of water for the reaction as well as the catalyst deactivation. It was concluded that the methanol formation from CO2 proceeds through two routes: one is the direct hydrogenation of CO2 to methanol and another is the one which pass through the CO formation. The Zr-promoted catalyst gave methanol and CO at the selectivity ratio of 0.4 to 0.6, whereas the un-promoted catalyst gave only CO at the initial stage of the reaction. It was claimed that the doped Zr promote the in-situ reduction of oxidized Cu (which should be caused by the reaction with the co-product H2O) by H 2 to increase the content of reduced Cu (active site) and thus the catalyst activity. The promoted reductivity of the Zr-containing catalyst prevents the crystal growth of CuOx which cause the irreversible deactivation of catalyst.
- Li, Congming,Yuan, Xingdong,Fujimoto, Kaoru
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- Comparative study of hydrotalcite-derived supported Pd2Ga and PdZn intermetallic nanoparticles as methanol synthesis and methanol steam reforming catalysts
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An effective and versatile synthetic approach to produce well-dispersed supported intermetallic nanoparticles is presented that allows a comparative study of the catalytic properties of different intermetallic phases while minimizing the influence of differences in preparation history. Supported PdZn, Pd2Ga, and Pd catalysts were synthesized by reductive decomposition of ternary Hydrotalcite-like compounds obtained by co-precipitation from aqueous solutions. The precursors and resulting catalysts were characterized by HRTEM, XRD, XAS, and CO-IR spectroscopy. The Pd2+ cations were found to be at least partially incorporated into the cationic slabs of the precursor. Full incorporation was confirmed for the PdZnAl-Hydrotalcite-like precursor. After reduction of Ga- and Zn-containing precursors, the intermetallic compounds Pd2Ga and PdZn were present in the form of nanoparticles with an average diameter of 6 nm or less. Tests of catalytic performance in methanol steam reforming and methanol synthesis from CO2 have shown that the presence of Zn and Ga improves the selectivity to CO2 and methanol, respectively. The catalysts containing intermetallic compounds were 100 and 200 times, respectively, more active for methanol synthesis than the monometallic Pd catalyst. The beneficial effect of Ga in the active phase was found to be more pronounced in methanol synthesis compared with steam reforming of methanol, which is likely related to insufficient stability of the reduced Ga species in the more oxidizing feed of the latter reaction. Although the intermetallic catalysts were in general less active than a Cu-/ZnO-based material prepared by a similar procedure, the marked changes in Pd reactivity upon formation of intermetallic compounds and to study the tunability of Pd-based catalysts for different reactions.
- Ota, Antje,Kunkes, Edward L.,Kasatkin, Igor,Groppo, Elena,Ferri, Davide,Poceiro, Beatriz,Navarro Yerga, Rufino M.,Behrens, Malte
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- Cu-Erionite Zeolite Achieves High Yield in Direct Oxidation of Methane to Methanol by Isothermal Chemical Looping
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We herein report that a copper-ion-exchanged erionite zeolite (Cu-ERI) exhibited a methanol yield as high as 147 μmol/g-zeolite, equaling 0.224 μmol/μmol-Cu, in the direct oxidation of methane to methanol. Moreover, this high methanol yield was achieved using an isothermal chemical looping with both oxygen activation and reaction with methane carried out at 300 °C, in contrast to the conventional stepwise protocol where activation is performed at a high temperature (450 °C and above) and the methane reaction at a lower temperature (typically 200 °C). Under isobaric conditions (1 bar), the Cu-ERI still gave a high yield of 80 μmol/g-zeolite after a single aqueous extraction of methanol. Such improvements indicate that high yields can be obtained over Cu-ERI in the direct conversion of methane to methanol by chemical looping without any temperature or pressure swing.
- Knorpp, Amy J.,Liu, Zhendong,Mizuno, Stefanie C. M.,Newton, Mark A.,Okubo, Tatsuya,Sushkevich, Vitaly L.,Van Bokhoven, Jeroen A.,Wakihara, Toru,Zhu, Jie
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- Self-sufficient and exclusive oxygenation of methane and its source materials with oxygen to methanol via metgas using oxidative bi-reforming
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A combination of complete methane combustion with oxygen of the air coupled with bi-reforming leads to the production of metgas (H2/CO in 2:1 mole ratio) for exclusive methanol synthesis. The newly developed oxidative bi-reforming allows direct oxygenation of methane to methanol in an overall economic and energetically efficient process, leaving very little, if any, carbon footprint or byproducts.
- Olah, George A.,Prakash, G. K. Surya,Goeppert, Alain,Czaun, Miklos,Mathew, Thomas
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- Spinel-Structured ZnCr2O4 with Excess Zn Is the Active ZnO/Cr2O3 Catalyst for High-Temperature Methanol Synthesis
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A series of ZnO/Cr2O3 catalysts with different Zn:Cr ratios was prepared by coprecipitation at a constant pH of 7 and applied in methanol synthesis at 260-300 °C and 60 bar. The X-ray diffraction (XRD) results showed that the calcined catalysts with ratios from 65:35 to 55:45 consist of ZnCr2O4 spinel with a low degree of crystallinity. For catalysts with Zn:Cr ratios smaller than 1, the formation of chromates was observed in agreement with temperature-programmed reduction results. Raman and XRD results did not provide evidence for the presence of segregated ZnO, indicating the existence of Zn-rich nonstoichiometric Zn-Cr spinel in the calcined catalyst. The catalyst with Zn:Cr = 65:35 exhibits the best performance in methanol synthesis. The Zn:Cr ratio of this catalyst corresponds to that of the Zn4Cr2(OH)12CO3 precursor with hydrotalcite-like structure obtained by coprecipitation, which is converted during calcination into a nonstoichiometric Zn-Cr spinel with an optimum amount of oxygen vacancies resulting in high activity in methanol synthesis. Density functional theory calculations are used to examine the formation of oxygen vacancies and to measure the reducibility of the methanol synthesis catalysts. Doping Cr into bulk and the (10-10) surface of ZnO does not enhance the reducibility of ZnO, confirming that Cr:ZnO cannot be the active phase. The (100) surface of the ZnCr2O4 spinel has a favorable oxygen vacancy formation energy of 1.58 eV. Doping this surface with excess Zn charge-balanced by oxygen vacancies to give a 60% Zn content yields a catalyst composed of an amorphous ZnO layer supported on the spinel with high reducibility, confirming this as the active phase for the methanol synthesis catalyst.
- Song, Huiqing,Laudenschleger, Daniel,Carey, John J.,Ruland, Holger,Nolan, Michael,Muhler, Martin
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- Understanding and Optimizing the Performance of Cu-FER for The Direct CH4 to CH3OH Conversion
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Cu-exchanged zeolites with the Ferrierite topology were investigated in the direct CH4 to CH3OH conversion. Samples with a systematic compositional variation in terms of Na/Al and Cu/Al ratios where synthesized by liquid ion exchange. The presence of Na is observed to be beneficial for the Cu exchange and thereby higher Cu loadings were achieved. The overall performance of Cu-FER samples depends on Cu loading as well as the conditions of the reaction. Elevated O2 activation temperature as well as long CH4 loading times are proven to enhance the CH3OH yield of the Cu-FER sample with Cu/Al=0.2. In addition, the productivity depends on the Cu/Al ratio, at low values the sample is almost inactive indicating a Cu threshold that needs to be surpassed. We employed X-ray absorption and IR of adsorbed CO spectroscopies in order to rationalize the performance as well as the effect of Cu/Al ratio. From the in situ spectroscopies we ultimately establish structure-activity relationships between the reducibility of Cu species and the CH3OH yield.
- Pappas, Dimitrios K.,Borfecchia, Elisa,Dyballa, Michael,Lomachenko, Kirill A.,Martini, Andrea,Berlier, Gloria,Arstad, Bj?rnar,Lamberti, Carlo,Bordiga, Silvia,Olsbye, Unni,Svelle, Stian,Beato, Pablo
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- A novel low-temperature methanol synthesis method from CO/H2/CO2 based on the synergistic effect between solid catalyst and homogeneous catalyst
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The activity of a binary catalyst in alcoholic solvents for methanol synthesis from CO/H2/CO2 at low temperature was investigated in a concurrent synthesis course. Experiment results showed that the combination of homogeneous potassium formate catalyst and solid copper-magnesia catalyst enhanced the conversion of CO2-containing syngas to methanol at temperature of 423-443 K and pressure of 3-5 MPa. Under a contact time of 100 g h/mol, the maximum conversion of total carbon approached the reaction equilibrium and the selectivity of methanol was 99%. A reaction pathway involving esterification and hydrogenolysis of esters was postulated based on the integrative and separate activity tests, along with the structural characterization of the catalysts. Both potassium formate for the esterification as well as Cu/MgO for the hydrogenolysis were found to be crucial to this homogeneous and heterogeneous synergistically catalytic system. CO and H2 were involved in the recycling of potassium formate.
- Zhao, Tian-Sheng,Zhang, Kun,Chen, Xuri,Ma, Qingxiang,Tsubaki, Noritatsu
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- Effects of alkaline-earth oxides on the performance of a CuO-ZrO2 catalyst for methanol synthesis via CO2 hydrogenation
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CuO-ZrO2 catalysts doped with alkaline-earth oxides were prepared by a urea-nitrate combustion method. The catalysts were characterized with N2 adsorption, N2O titration, XRD, H2-TPR, XPS and CO2-TPD techniques and tested for methanol synthesis from CO2 hydrogenation. With the incorporation of alkaline-earth oxides, the copper surface area increases remarkably, whereas the reducibility of CuO in the catalyst decreases. The doping of alkaline-earth oxides leads to an increase in the strength and contribution of the strong basic site on the catalyst surface. The results of catalytic tests indicate that the conversion of CO2 depends not only on the copper surface area but also on the reducibility of CuO in the catalyst, and the latter is a predominant factor for CaO-, SrO- and BaO-doped CuO-ZrO2 catalysts. The selectivity to methanol is related to the basicity of the catalyst. Moreover, the influence of the doping amount of MgO on the properties of CuO-ZrO2 was investigated, and the optimum catalytic activity is obtained as the amount of MgO doping is 5 mol%.
- Zhong, Chenglin,Guo, Xiaoming,Mao, Dongsen,Wang, Song,Wu, Guisheng,Lu, Guanzhong
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- Continuous supercritical low-temperature methanol synthesis with n-butane as a supercritical fluid
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A process of supercritical low-temperature methanol synthesis from syngas containing CO2 was carried out at 443 K and 60 bar. The 2-butanol and n-butane was used as catalytic solvent and supercritical medium, respectively. The results showed that the total carbon conversion, especially the CO 2 conversion of the methanol synthesis was increased significantly under the supercritical condition. Copyright
- Reubroycharoen, Prasert,Bao, Jun,Zhang, Yi,Tsubaki, Noritatsu
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- Reversible Switching of Catalytic Activity by Shuttling an Atom into and out of Gold Nanoclusters
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It is challenging to control the catalyst activation and deactivation by removal and addition of only one central atom, as it is almost impossible to precisely abstract an atom from a conventional catalyst and analyze its catalysis. Here we report that th
- Cai, Xiao,Saranya, Govindarajan,Shen, Kangqi,Chen, Mingyang,Si, Rui,Ding, Weiping,Zhu, Yan
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- Molybdenum-Bismuth Bimetallic Chalcogenide Nanosheets for Highly Efficient Electrocatalytic Reduction of Carbon Dioxide to Methanol
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Methanol is a very useful platform molecule and liquid fuel. Electrocatalytic reduction of CO2 to methanol is a promising route, which currently suffers from low efficiency and poor selectivity. Herein we report the first work to use a Mo-Bi bimetallic chalcogenide (BMC) as an electrocatalyst for CO2 reduction. By using the Mo-Bi BMC on carbon paper as the electrode and 1-butyl-3-methylimidazolium tetrafluoroborate in MeCN as the electrolyte, the Faradaic efficiency of methanol could reach 71.2 % with a current density of 12.1 mA cm-2, which is much higher than the best result reported to date. The superior performance of the electrode resulted from the excellent synergistic effect of Mo and Bi for producing methanol. The reaction mechanism was proposed and the reason for the synergistic effect of Mo and Bi was discussed on the basis of some control experiments. This work opens a way to produce methanol efficiently by electrochemical reduction of CO2.
- Sun, Xiaofu,Zhu, Qinggong,Kang, Xinchen,Liu, Huizhen,Qian, Qingli,Zhang, Zhaofu,Han, Buxing
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- Formation of Methanol by Microwave-Plasma Reduction of CO2 with H2O
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Reduction of CO2 with H2O was carried out by microwave plasma for the formation of methanol. The results of steam chromatography and mass spectrometry showed that the plasma products contained methanol. The methanol formation was also found in H2O-plasma-cleaning process, in which materials which had been deposited in the reaction between CO2 and H2O were removed. The most adequate plasma energy density for the formation of methanol was found to be 0.26 GJ kg-1 of W/FM. The methanol yield at the system pressure of 400 Pa was 3.5 times higher than at 240 Pa for both the CO2-H2O synthetic process and the H2O-cleaning process.
- Ihara, Tatsuhiko,Ouro, Takashi,Ochiai, Tomoyuki,Kiboku, Mitsuo,Iriyama, Yu
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- Characterization of modified Fischer-Tropsch catalysts promoted with alkaline metals for higher alcohol synthesis
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Two series of Cu/Co/Cr modified Fischer-Tropsch catalyst promoted with Zn or Mn and an alkaline metal (Me: Li, Na, K, Rb, Cs) were prepared by co-precipitation method and tested for high alcohol synthesis (HAS) at one hour on-stream and at two temperatures, 300 and 350 °C. The results indicate that the best selectivity toward high alcohols depends on temperature and catalysts composition and is obtained as follows: a) at 300 °C over catalysts without Zn and containing K, Na and Rb; b) at 350 °C over catalysts without Zn and containing K; c) at 350 °C over catalysts containing Zn as well as Li and Cs.
- Cosultchi, Ana,Perez-Luna, Miguel,Morales-Serna, Jose Antonio,Salmon, Manuel
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- Conversion of CH4 to CH3OH: Reactions of CoO+ with CH4 and D2, Co+ with CH3OD and D2O, and Co+(CH3OD) with Xe
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The mechanisms and energetics involved in the conversion of CH4 to CH3OH by CoO+ are examined by using guided ion beam mass spectrometry. The forward and reverse reactions, CoO+ + CH4 ? Co+ + CH3OH, the collisional activation of Co+(CH3OH), and the related reactions, CoO+ + D2 ? Co+ + D2O, are studied. It is found that the oxidations of methane and D2 by CoO+, both exothermic reactions, do not occur until overcoming activation barriers of 0.56 ± 0.08 and 0.75 ± 0.04 eV, respectively. The behavior of the forward and reverse reactions in both systems is consistent with reactions that proceed via the insertion intermediates R-Co+-OH, where R = CH3 or H. The barrier is probably attributable to a four-centered transition state associated with addition of RH across the CoO+ bond. In the Co+ + CH3OH system (where CH3OD labeled reactant is used), reactions explained by initial C-H and O-H activation are also observed. The reaction mechanisms and potential energy surfaces for these systems are derived and discussed. Phase space theory calculations are used to help verify these details for the CoO+ + D2 system. Thermochemistry for several species including CoOH+, CoD+, CoH, CoCH3+, Co+(CH3OD), CoOCH3+, and possibly OCoCH3+ is derived from measurements of reaction thresholds.
- Chen, Yu-Min,Clemmer,Armentrout
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- ACID-CATALYZED HYDROLYSIS OF 2-METHOXYPROPENAL
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2-Methoxypropenal in acid media undergoes general acid-catalyzed hydrolysis with formation of 2-oxopropanal.The kinetics of this reaction were studied, the rate constants established, and a reaction mechanism is suggested.Hydrolysis of 2-methoxypropenal is governed by a mechanism of the vinyl ether type, and the presence of the aldehyde group causes a decrease in the reaction rate.The analogy of the acid-catalyzed hydrolysis of 2-methoxypropenal to that of a vinyl ether was shown by the solvent isotope-effect, kD/kH=0.41, and the value of the Broensted exponent, α=0.60.The activation parameters found and quantum-chemical calculations of charge distribution in 2-methoxypropenal and other model compounds were also utilized to explain the mechanism of the acid-catalyzed hydrolysis of the title compound.
- Fedoronko, Michal,Petrusova, Maria,Tvaroska, Igor
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- Selective electrocatalytic oxidation of a re-methyl complex to methanol by a surface-bound RuII polypyridyl catalyst
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The complex [Ru(Mebimpy)(4,′-((HO)2OPCH2)2bpy)(OH2)]2+ surface bound to tin-doped indium oxide mesoporous nanoparticle film electrodes (nanoITO-RuII(OH2)2+) is an electrocatalyst for the selective oxidation of methylrhenium trioxide (MTO) to methanol in acidic aqueous solution. Oxidative activation of the catalyst to nanoITO-RuIV(OH)3+ induces oxidation of MTO. The reaction is first order in MTO with rate saturation observed at [MTO] > 12 mM with a limiting rate constant of k = 25 s-1. Methanol is formed selectively in 87% Faradaic yield in controlled potential electrolyses at 1.3 V vs NHE. At higher potentials, oxidation of MTO by nanoITO-RuV(O)3+ leads to multiple electrolysis products. The results of an electrochemical kinetics study point to a mechanism in which surface oxidation to nanoITO-RuIV(OH)3+ is followed by direct insertion into the rhenium-methyl bond of MTO with a detectable intermediate.
- Coggins, Michael K.,Mndez, Manuel A.,Concepcion, Javier J.,Periana, Roy A.,Meyer, Thomas J.
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- Carbon Dioxide Conversion to Methanol over Size-Selected Cu4 Clusters at Low Pressures
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The activation of CO2 and its hydrogenation to methanol are of much interest as a way to utilize captured CO2. Here, we investigate the use of size-selected Cu4 clusters supported on Al2O3 thin films for CO2 reduction in the presence of hydrogen. The catalytic activity was measured under near-atmospheric reaction conditions with a low CO2 partial pressure, and the oxidation state of the clusters was investigated by in situ grazing incidence X-ray absorption spectroscopy. The results indicate that size-selected Cu4 clusters are the most active low-pressure catalyst for catalytic CO2 conversion to CH3OH. Density functional theory calculations reveal that Cu4 clusters have a low activation barrier for conversion of CO2 to CH3OH. This study suggests that small Cu clusters may be excellent and efficient catalysts for the recycling of released CO2.
- Liu, Cong,Yang, Bing,Tyo, Eric,Seifert, Soenke,Debartolo, Janae,Von Issendorff, Bernd,Zapol, Peter,Vajda, Stefan,Curtiss, Larry A.
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- New and revisited insights into the promotion of methanol synthesis catalysts by CO2
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CO hydrogenation, CO2 hydrogenation, and water-gas shift (WGS) reactions have been simultaneously investigated over industry-like catalysts based on Cu-ZnO-Al2O3, under methanol synthesis conditions (513 K, 5.0 MPa). For this, a novel methodology has been applied: the concentration of carbon dioxide in the syngas feed was consecutively increased (R = CO2:(CO + CO2) = 0-100) resulting in a volcano-type plot of the rate of methanol formation and forming a hysteresis loop when decreasing the CO2 concentration again. H2O co-feeding experiments revealed that the enhancement of activity can be correlated with the WGS activity linking both hydrogenation paths of CO and CO2. On the other hand, excessive amounts of surface hydroxyls seem to inhibit methanol production, explaining the drop in activity at high CO2 concentrations. An investigation of the catalytic performance was accompanied by an extensive characterisation of the fresh and used catalytic materials by X-ray diffraction, temperature-programmed reduction by H2, N 2O pulse chemisorption, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. It was shown that the copper surface area affects the CO2 hydrogenation; however, this parameter is unambiguously not the key descriptor for CO2-promoted methanol synthesis, which is a consequence of the synergistic interaction of zinc oxide and copper. This structural feature is further promoted by Al2O3 through stabilisation of the surface. The position of the activity maximum is determined by the surface ratio Cu:Zn. The hysteresis behaviour is a result of the continuous decrease of Cu dispersion and the fixation of copper species in its monovalent oxidation state, both detrimental for CO2 hydrogenation. CO hydrogenation is strongly affected by the Cu:Zn bulk ratio and thus the reducibility of the catalyst. These facts could be substantiated by the use of impregnated model catalysts. The Royal Society of Chemistry.
- Martin, Oliver,Perez-Ramirez, Javier
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- Selective Photoreduction of Carbon Dioxide to Methanol on Titanium Dioxide Photocatalysts in Propylene Carbonate Solution
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Methanol is selectively photosynthesised from carbon dioxide using TiO2 photocatalysts in propylene carbonate containing propan-2-ol as a hole scavenger.
- Kuwabata, Susumu,Uchida, Hiroyuki,Ogawa, Akihiro,Hirao, Shigeki,Yoneyama, Hiroshi
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- Fluorine-modified Cu/Zn/Al/Zr catalysts via hydrotalcite-like precursors for CO2 hydrogenation to methanol
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Fluorine-modified Cu/Zn/Al/Zr catalysts were prepared by calcination of the fluorine-containing Cu/Zn/Al/Zr hydrotalcite-like compounds and tested for CO2 hydrogenation to methanol. The results revealed that the CH 3OH selectivity was greatly improved by the remarkable increase of the proportion of strongly basic sites, while the CO2 conversion decreased slightly. It is also found that the activity of catalysts is closely related to the synergy between the Cu and basic sites. The CH3OH yield for the fluorine-modified Cu/Zn/Al/Zr catalysts was higher than that for the fluorine-free catalysts; thus, the introduction of fluorine favored the methanol formation.
- Gao, Peng,Li, Feng,Zhan, Haijuan,Zhao, Ning,Xiao, Fukui,Wei, Wei,Zhong, Liangshu,Sun, Yuhan
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- Effect of Γ-alumina nanorods on CO hydrogenation to higher alcohols over lithium-promoted CuZn-based catalysts
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To achieve high catalytic activities and long-term stability to produce higher alcohols via CO hydrogenation, the catalytic activities were tuned by controlling the loading amounts of γ-alumina nanorods and Al3+ ions added to modify Cu-Zn catalysts promoted with Li. The selectivity of higher alcohols and the CO conversion to higher alcohols over a Li-modified Cu0.45Zn0.45Al0.1 catalyst supported on 10% nanorods were 1.8 and 2.7 times higher than those with a Cu-Zn catalyst without nanorods and Al3+ ions, respectively. The introduction of the thermally and chemically stable γ-Al2O3 nanorod support and of Al3+ to the modified catalysts improves the catalytic activities by decreasing the crystalline size of CuO and increasing the total basicity. Along with the nanorods, a refractory CuAl2O4 formed by the thermal reaction of CuO and Al3+ enhances the long-term stability by increasing the resistance to sintering of the catalyst.
- Choi, SuMin,Kang, YoungJong,Kim, SangWoo
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- Isolated single-atom Pt sites for highly selective electrocatalytic hydrogenation of formaldehyde to methanol
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The direct electrochemical conversion of noxious formaldehyde into value-added chemicals is a quite promising technique for resolving the increasingly serious environmental issue arising from industrial formaldehyde-containing wastewater. However, thus far, it has not been examined, to the best of our knowledge. This study reports the electrocatalytic hydrogenation of formaldehyde to methanol in a neutral aqueous medium under ambient conditions over a Pt single-atom catalyst, and this catalyst exhibits a favorable methanol yield rate and a high faradaic efficiency of 30.7 mg h-1 mgcat.-1 and 95.8% at -0.8 V versus the reversible hydrogen electrode in 0.1 M Na2SO4. Also, it exhibits excellent durability. Atomic-scale structural characterization and theoretical calculations revealed that the above-mentioned efficient performance is related to atomically dispersed Pt-O sites, which could lower the free-energy change for the chemisorption of formaldehyde and activate the C-H bond.
- Hu, Guangzhi,Liu, Xijun,Liu, Yifan,Luo, Jun,Mi, Yuying,Peng, Xianyun,Tang, Xiaolong,Wen, Yanfeng,Zhao, Shunzheng,Zhuo, Longchao
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- CO2 Conversion into Methanol Using Granular Silicon Carbide (α6H-SiC): A Comparative Evaluation of 355 nm Laser and Xenon Mercury Broad Band Radiation Sources
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Granular silicon carbide (α6H-SiC) was investigated as a photo-reduction catalyst for CO2 conversion into methanol using a 355 nm laser from the third harmonic of pulsed Nd:YAG laser and 500 W collimated xenon mercury (XeHg) broad band lamp. The reaction cell was filled with distilled water, α6H-SiC granules and pressurized with CO2 gas at 50 psi. Maximum molar concentration of methanol achieved was 1.25 and 0.375 mmol/l and the photonic efficiencies of CO2 conversion into methanol achieved were 1.95 and 1.16 % using the laser and the XeHg lamp respectively. The selectivity of methanol produced using the laser irradiation was 100 % as compared to about 50 % with the XeHg lamp irradiation. The band gap energy of silicon carbide was estimated to be 3.17 eV and XRD demonstrated that it is a highly crystalline material. This study demonstrated that commercially available granular silicon carbide is a promising photo-reduction catalyst for CO 2 into methanol. Graphical Abstract: Gas Chromatograms of reaction products collected at 30-120 min irradiation in the presence of 355 nm laser having 40 mJ/pulse energy. The inset shows the comparison of retention time of GC peaks with the methanol standard and it is at 2.46 min.[Figure not available: see fulltext.]
- Gondal, Mohammed Ashraf,Ali, Mohammed Ashraf,Dastageer, Mohamed Abdulkader,Chang, Xiaofeng
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- Development of molecular and solid catalysts for the direct low-temperature oxidation of methane to methanol
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The direct low-temperature oxidation of methane to methanol is demonstrated on a highly active homogeneous molecular catalyst system and on heterogeneous molecular catalysts based on polymeric materials possessing ligand motifs within the material structure. The N-(2-methylpropyl)-4,5-diazacarbazolyl-dichloro-platinum(II) complex reaches significantly higher activity compared to the well-known Periana system and allows first conclusions on electronic and structural requirements for high catalytic activity in this reaction. Interestingly, comparable activities could be achieved utilizing a platinum modified poly(benzimidazole) material, which demonstrates for the first time a solid catalyst with superior activity compared to the Periana system. Although the material shows platinum leaching, improved activity and altered electronic properties, compared to the conventional Periana system, support the proposed conclusions on structure-activity relationships. In comparison, platinum modified triazine-based catalysts show lower catalytic activity, but rather stable platinum coordination even after several catalytic cycles. Based on these systems, further development of improved solid catalysts for the direct low-temperature oxidation of methane to methanol is feasible.
- Palkovits, Regina,von Malotki, Christian,Baumgarten, Martin,Müllen, Klaus,Baltes, Christian,Antonietti, Markus,Kuhn, Pierre,Weber, Jens,Thomas, Arne,Schüth, Ferdi
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- Continuous precipitation of Cu/ZnO/Al2O3 catalysts for methanol synthesis in microstructured reactors with alternative precipitating agents
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Ternary Cu/ZnO/Al2O3 catalyst systems were systematically prepared by innovative synthesis routes in microstructured synthesis setups, allowing to study different types of micromixers. The coprecipitation in the slit plate and valve-assisted mixers was operated continuously under exact control of pH, temperature, concentration and ageing time. Due to the enhanced surface to volume ratio in microstructured reactors, a precise temperature control and efficient mixing of the reactants are enabled. The precipitation was performed with sodium, ammonium and potassium carbonate as well as sodium hydroxide. To evaluate the potential of the novel synthesis routes, reference samples in a conventional batch process were prepared. The catalysts were synthesized according to the constant pH method with a molar ratio of 60:30:10 for copper, zinc and aluminum. The synthesis routes applied have a significant influence on the structures of hydroxycarbonate precursors and on the catalytic activity in methanol synthesis. XRD patterns of hydroxycarbonate precursors from the synthesis in micromixers, especially using ammonium carbonate as precipitating agent, display high crystallinity and sharp reflections of malachite and rosasite. Cu/ZnO/Al2O3 catalysts prepared in continuously operated micromixers in general show higher specific copper surface areas than catalysts prepared in conventional batch processes. The highest methanol productivity of all prepared catalyst systems was observed with the catalyst precipitated in the slit plate mixer with ammonium carbonate.
- Simson, Georg,Prasetyo, Eko,Reiner, Stefanie,Hinrichsen, Olaf
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- A study on the precipitating and aging processes of CuO/ZnO/Al2O3 catalysts synthesized in micro-impinging stream reactors
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CuO/ZnO/Al2O3 catalyst precursors were precipitated in a novel micro-impinging stream reactor (MISR) and a traditional stirred tank reactor (STR), respectively, followed by a period time of aging in the mother liquid. Being different from the simultaneous precipitating and aging of catalyst precursors within the same STR reactor, these two processes occurred in two separate containers in the MISR route, hence providing a more uniform and steady environment for both the precipitating and aging processes on top of the higher micromixing efficiency and better process control of the MISR. Therefore, substantial changes in the phase compositions and microstructures of the catalyst precursors were obtained with MISR, which resulted in smaller and more homogeneous catalyst particles with a larger BET surface area and specific copper surface area, better Cu/Zn dispersion as well as higher catalytic activity when compared to those prepared in the STR. The aging process also played an important role in catalyst preparation and it could be controlled more easily and precisely in the MISR route to form a more desirable phase structure, morphology and eventually more superior catalytic performance in methanol synthesis for the final catalysts.
- Zhang, Qing-Cheng,Cheng, Kun-Peng,Wen, Li-Xiong,Guo, Kai,Chen, Jian-Feng
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- Stable amorphous georgeite as a precursor to a high-activity catalyst
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Copper and zinc form an important group of hydroxycarbonate minerals that include zincian malachite, aurichalcite, rosasite and the exceptionally rare and unstable - and hence little known and largely ignored - georgeite. The first three of these minerals are widely used as catalyst precursors for the industrially important methanol-synthesis and low-temperature water-gas shift (LTS) reactions, with the choice of precursor phase strongly influencing the activity of the final catalyst. The preferred phase is usually zincian malachite. This is prepared by a co-precipitation method that involves the transient formation of georgeite; with few exceptions it uses sodium carbonate as the carbonate source, but this also introduces sodium ions - a potential catalyst poison. Here we show that supercritical antisolvent (SAS) precipitation using carbon dioxide (refs 13, 14), a process that exploits the high diffusion rates and solvation power of supercritical carbon dioxide to rapidly expand and supersaturate solutions, can be used to prepare copper/zinc hydroxycarbonate precursors with low sodium content. These include stable georgeite, which we find to be a precursor to highly active methanol-synthesis and superior LTS catalysts. Our findings highlight the value of advanced synthesis methods in accessing unusual mineral phases, and show that there is room for exploring improvements to established industrial catalysts.
- Kondrat, Simon A.,Smith, Paul J.,Wells, Peter P.,Chater, Philip A.,Carter, James H.,Morgan, David J.,Fiordaliso, Elisabetta M.,Wagner, Jakob B.,Davies, Thomas E.,Lu, Li,Bartley, Jonathan K.,Taylor, Stuart H.,Spencer, Michael S.,Kiely, Christopher J.,Kelly, Gordon J.,Park, Colin W.,Rosseinsky, Matthew J.,Hutchings, Graham J.
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- Electrochemical reduction of carbon dioxide with an electrode mediator and homogeneous catalysts
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Carbon dioxide has been reduced catalytically to methanol with an electrode mediator and homogeneous catalysts, using a hydrogen fuel cell as an energy source to regenerate the active mediator. Thermodynamic assessment predicts that the reversible potential for the reaction H+ + e- = 1/2 H2 should be more negative than that for the reaction CO2 + 6H+ + 6e- = CH3OH + H2O whenever a fuel cell with hydrogen as the fuel and CO2 as the oxidant is feasible. As reaction proceeded, the pH of the catholyte rose but that of the anolyte dropped, until finally reduction of CO2 ceased. Hence, adjustment of the pH values in both temperatures was necessary to maintain CO2 reduction over long time periods.
- Ogura,Migita,Nagaoka
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- The partial oxidation of methane to methanol with nitrite and nitrate melts
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The effect of reduced oxygen species on the partial oxidation of methane to methanol was examined with nitrite melts. The experimental results support the suggestion that the formation of methanol or C2 compounds depends on different reduced oxygen species, as observed in our previous work using nitrate melts. It has been suggested that the partial oxidation of methane proceeds to CH3OH or C2 compounds via parallel pathways. This suggestion was verified by increasing the oxygen concentration to carry out the partial oxidation of methane in 25 mol% NaNO3 - 75 mol% KNO3 melts. A methanol selectivity of 8.2% and a methanol yield of 0.43% were observed with CH4/O2 = 15/1 at 575 °C, whereas with CH4/O2 = 7/1 methanol selectivity and yield increased to 23.7% and 1.1%, respectively. The results further confirm the contribution of the superoxide ion O2- on methanol formation.
- Lee, Bor-Jih,Kitsukawa, Shigeo,Nakagawa, Hidemoto,Asakura, Shukuji,Fukuda, Kenzo
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- Low pressure CO2 hydrogenation to methanol over gold nanoparticles activated on a CeOx/TiO2 Interface
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Capture and recycling of CO2 into valuable chemicals such as alcohols could help mitigate its emissions into the atmosphere. Due to its inert nature, the activation of CO2 is a critical step in improving the overall reaction kinetics during its chemical conversion. Although pure gold is an inert noble metal and cannot catalyze hydrogenation reactions, it can be activated when deposited as nanoparticles on the appropriate oxide support. In this combined experimental and theoretical study, it is shown that an electronic polarization at the metal-oxide interface of Au nanoparticles anchored and stabilized on a CeOx/TiO2 substrate generates active centers for CO2 adsorption and its low pressure hydrogenation, leading to a higher selectivity toward methanol. This study illustrates the importance of localized electronic properties and structure in catalysis for achieving higher alcohol selectivity from CO2 hydrogenation.
- Yang, Xiaofang,Kattel, Shyam,Senanayake, Sanjaya D.,Boscoboinik, J. Anibal,Nie, Xiaowa,Graciani, Jesús,Rodriguez, José A.,Liu, Ping,Stacchiola, Darío J.,Chen, Jingguang G.
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- Carbon dioxide hydrogenation to methanol over Cu/ZrO2/CNTs: Effect of carbon surface chemistry
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Methanol synthesis from CO2 hydrogenation in a fixed-bed plug flow reactor was investigated over Cu-ZrO2 catalysts supported on CNTs bearing various functional groups. The highest methanol activity (turnover frequency 1.61 × 10-2 s-1, space time yield 84.0 mg gcat-1 h-1) was obtained over the Cu/ZrO2/CNTs catalyst (CZ/CNT-3) with CNTs functionalized by nitrogen-containing groups and Cu loading only about 10.3 wt% under the reaction conditions of 260 °C, 3.0 MPa, V(H2):V(CO2):V(N2) = 69:23:8 and GHSV of 3600 h-1. The catalysts were fully characterized by N2 physisorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of H2 (H2-TPD) techniques. The excellent performance of CZ/CNT-3 is attributed to the presence of nitrogen-containing groups on the CNTs surface, which increase the dispersion of copper oxides, promote their reduction, decreases the crystal size of Cu, and enhances H2 and CO2 adsorption capability, thus leading to good catalytic performance towards methanol synthesis. This journal is
- Wang, Guannan,Chen, Limin,Sun, Yuhai,Wu, Junliang,Fu, Mingli,Ye, Daiqi
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- New catalyst systems for the catalytic conversion of methane into methanol
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Palladium complexes with N-heterocyclic carbenes, such as in the biscarbene chelate ligands shown (R = tBu, Me; X = Br, I), have proved to be stable in strongly acidic media and were tested in the catalytic conversion of methane into methanol. The prominent influence of the halogenide ligand is shown since, in contrast to the bromo complex, the iodo complex does not catalyze the reaction. The steric bulk of the substituents R also influences the catalytic activity.
- Muehlhofer, Michael,Strassner, Thomas,Herrmann, Wolfgang A.
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- Hydrogenation of Esters by Manganese Catalysts
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The hydrogenation of esters catalyzed by a manganese complex of phosphine-aminopyridine ligand was developed. Using this protocol, a variety of (hetero)aromatic and aliphatic carboxylates including biomass-derived esters and lactones were hydrogenated to primary alcohols with 63–98% yields. The manganese catalyst was found to be active for the hydrogenation of methyl benzoate, providing benzyl alcohol with turnover numbers (TON) as high as 45,000. Investigation of catalyst intermediates indicated that the amido manganese complex was the active catalyst species for the reaction. (Figure presented.).
- Li, Fu,Li, Xiao-Gen,Xiao, Li-Jun,Xie, Jian-Hua,Xu, Yue,Zhou, Qi-Lin
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- Binary Au–Cu Reaction Sites Decorated ZnO for Selective Methane Oxidation to C1 Oxygenates with Nearly 100% Selectivity at Room Temperature
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Direct and efficient oxidation of methane to methanol and the related liquid oxygenates provides a promising pathway for sustainable chemical industry, while still remaining an ongoing challenge owing to the dilemma between methane activation and overoxidation. Here, ZnO with highly dispersed dual Au and Cu species as cocatalysts enables efficient and selective photocatalytic conversion of methane to methanol and one-carbon (C1) oxygenates using O2 as the oxidant operated at ambient temperature. The optimized AuCu–ZnO photocatalyst achieves up to 11225 μmol·g–1·h–1 of primary products (CH3OH and CH3OOH) and HCHO with a nearly 100% selectivity, resulting in a 14.1% apparent quantum yield at 365 nm, much higher than the previous best photocatalysts reported for methane conversion to oxygenates. In situ EPR and XPS disclose that Cu species serve as photoinduced electron mediators to promote O2 activation to ?OOH, and simultaneously that Au is an efficient hole acceptor to enhance H2O oxidation to ?OH, thus synergistically promoting charge separation and methane transformation. This work highlights the significances of co-modification with suitable dual cocatalysts on simultaneous regulation of activity and selectivity.
- Gong, Zhuyu,Liu, Huifen,Luo, Lei,Ma, Jiani,Tang, Junwang,Xing, Jialiang,Xu, Youxun
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supporting information
p. 740 - 750
(2022/01/03)
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- Synthesis of phenol from degraded lignin using synergistic effect of iron-oxide based catalysts: Oxidative cracking ability and acid-base properties
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The effects of ZrO2 and TiO2 incorporated into Fe2O3 matrix on oxidative cracking of degraded lignin and on the acid-base properties were investigated. After lignin degradation, cracking into lower-molecular-weight products was greatest using ZrO2-FeOX. Reactivity of the lattice oxygen was evaluated using H2-TPR, which revealed that the reactivity was improved. Thus, ZrO2-FeOX promoted oxidative decomposition of lignin to oligomers. In the cracking of 2-methoxyphenol, TiO2-FeOX and ZrO2-FeOX resulted in a 5- to 6-fold greater yield of phenol than the yield over Fe2O3. According to Mulliken population analysis, the charge density difference between Fe-O increased by ca. 12% in TiO2-FeOX and ZrO2-FeOX as compared with Fe2O3. This result suggests that addition of TiO2 and ZrO2 improved the acid-base properties of the catalyst, which promoted demethoxylation of 2-methoxyphenol. Thus, ZrO2-FeOX enhanced oxidative decomposition using its lattice oxygen that converted degraded lignin into lower molecule oligomers, followed by demethoxylation to produce phenol.
- Fumoto, Eri,Ishimaru, Hiroya,Masuda, Takao,Nakasaka, Yuta,Sato, Shinya,Yoshikawa, Takuya
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- Acid-assisted hydrogenation of CO2to methanol using Ru(ii) and Rh(iii) RAPTA-type catalysts under mild conditions
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A highly efficient homogeneous catalyst system for production of CH3OH from CO2using single molecular defined ruthenium and rhodium RAPTA-type catalysts [Ru(η6-p-cymene)X2(PTA)] (X = I(1), Cl(2); PTA = 1,3,5-triaza-7-phosphaadamantane) and rhodium catalysts [Rh(η5-C5Me5)X2(PTA/PTA-BH3)] (X = Cl(3), H(4) and PTA-BH3, H(5)) developed in acidic media under mild conditions. A TON of 4752 is achieved using a [Ru(η6-p-cymene)I2(PTA)] catalyst which represents the first example of CO2hydrogenation to CH3OH using single molecular defined Ru and Rh RAPTA-type catalysts.
- Kumar, Abhinav,Kumar, Sanjay,Pandey, Indresh Kumar,Rath, Nigam P.,Sharma, Pooja,Trivedi, Manoj
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supporting information
p. 8941 - 8944
(2021/09/13)
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- Catalytic Partial Oxidation of Methane
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Systems and methods are provided for direct conversion of methane and/or ethane to methanol. The methods can include exposing methane to an oxidant, such as O2, in a solvent at conditions that are supercritical for the solvent while having a temperature of 310° C. or less, or about 300° C. or less, or about 290° C. or less. The solvent can correspond to an electron donor solvent that, when in a supercritical state, can complex with O2. By forming a complex with the O2, the supercritical electron donor solvent can facilitate conversion of alkane to methanol at short residence times while reducing or minimizing further oxidation of the methanol to other products.
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Paragraph 0056; 0066; 0072
(2021/10/30)
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- Unprecedentedly high efficiency for photocatalytic conversion of methane to methanol over Au-Pd/TiO2-what is the role of each component in the system?
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Direct and highly efficient conversion of methane to methanol under mild conditions still remains a great challenge. Here, we report that Au-Pd/TiO2 could directly catalyze the conversion of methane to methanol with an unprecedentedly high methanol yield of 12.6 mmol gcat-1 in a one-hour photocatalytic reaction in the presence of oxygen and water. Such an impressive efficiency is contributed by several factors, including the affinity between Au-Pd nanoparticles and intermediate species, the photothermal effect induced by visible light absorption of Au-Pd nanoparticles, the employment of O2 as a mild oxidant, and the effective dissolution of methanol in water. More importantly, for the first time, thermo-photo catalysis is demonstrated by the distinct roles of light. Namely, UV light is absorbed by TiO2 to excite charge carriers, while visible light is absorbed by Au-Pd nanoparticles to increase the temperature of the catalyst, which further enhances the driving force of corresponding redox reactions. These results not only provide a valuable guide for designing a photocatalytic system to realize highly efficient production of methanol, but also, highlight the great promise of thermo-photo catalysis. This journal is
- Cai, Xiaojiao,Fang, Siyuan,Hu, Yun Hang
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supporting information
p. 10796 - 10802
(2021/05/14)
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- High catalytic methane oxidation activity of monocationic μ-nitrido-bridged iron phthalocyanine dimer with sixteen methyl groups
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Herein, we report the highly potent catalytic methane oxidation activity of a monocationic μ-nitrido-bridged iron phthalocyanine dimer with 16 peripheral methyl groups. It was confirmed that this complex oxidized methane stably into MeOH, HCHO, and HCOOH in a catalytic manner in an acidic aqueous solution containing excess H2O2 at 60 °C. The total turnover number of the reaction reached 135 after 12 h, which is almost seven times higher than that of a monocatinoic μ-nitrido-bridged iron phthalocyanine dimer with no peripheral substituents. This suggests that the increased number of peripheral electron-donating substituents could have facilitated the generation of a reactive high-valent iron-oxo species as well as hydrogen abstraction from methane by the reactive iron-oxo species.
- Kura, Jyunichi,Tanaka, Kentaro,Toyoda, Yuka,Yamada, Yasuyuki
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supporting information
p. 6718 - 6724
(2021/05/26)
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- Enhancement and limits of the selective oxidation of methane to formaldehyde over V-SBA-15: Influence of water cofeed and product decomposition
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The possibility of a selective catalytic oxidation of methane to formaldehyde has been known for decades, and positive influences of water added to the reaction mixture and ultra-short contact times have been reported. In the present work, the complexity of interdependencies has been revealed. Specific parameter variations can increase conversion and selectivity of the target product. Surprisingly, formaldehyde formation over VOx species and its decomposition in gas phase were equally dependent on the partial pressure of the added water, so that the sweet spot can only be found by varying the residence time.
- Kunkel, Benny,Wohlrab, Sebastian
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- Fundamental insight into electrochemical oxidation of methane towards methanol on transition metal oxides
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Electrochemical oxidation of CH4 is known to be inefficient in aqueous electrolytes. The lower activity of methane oxidation reaction (MOR) is primarily attributed to the dominant oxygen evolution reaction (OER) and the higher barrier for CH4 activation on transition metal oxides (TMOs). However, a satisfactory explanation for the origins of such lower activity of MOR on TMOs, along with the enabling strategies to partially oxidize CH4 to CH3OH, have not been developed yet. We report here the activation of CH4 is governed by a previously unrecognized consequence of electrostatic (or Madelung) potential of metal atom in TMOs. The measured binding energies of CH4 on 12 different TMOs scale linearly with the Madelung potentials of the metal in the TMOs. The MOR active TMOs are the ones with higher CH4 binding energy and lower Madelung potential. Out of 12 TMOs studied here, only TiO2, IrO2, PbO2, and PtO2 are active for MOR, where the stable active site is the O on top of the metal in TMOs. The reaction pathway for MOR proceeds primarily through *CHx intermediates at lower potentials and through *CH3OH intermediates at higher potentials. The key MOR intermediate *CH3OH is identified on TiO2 under operando conditions at higher potential using transient open-circuit potential measurement. To minimize the overoxidation of *CH3OH, a bimetallic Cu2O3 on TiO2 catalysts is developed, in which Cu reduces the barrier for the reaction of *CH3 and *OH and facilitates the desorption of *CH3OH. The highest faradaic efficiency of 6% is obtained using Cu-Ti bimetallic TMO.
- Prajapati, Aditya,Collins, Brianna A.,Goodpaster, Jason D.,Singh, Meenesh R.
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- Integrated Capture and Conversion of CO2 to Methane Using a Water-lean, Post-Combustion CO2 Capture Solvent
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Integrated carbon capture and conversion of CO2 into materials (IC3M) is an attractive solution to meet global energy demand, reduce our dependence on fossil fuels, and lower CO2 emissions. Herein, using a water-lean post-combustion capture solvent, [N-(2-ethoxyethyl)-3-morpholinopropan-1-amine] (2-EEMPA), >90 % conversion of captured CO2 to hydrocarbons, mostly methane, is achieved in the presence of a heterogenous Ru catalyst under relatively mild reaction conditions (170 °C and 2 pressure). The catalytic performance was better in 2-EEMPA than in aqueous 5 m monoethanol amine (MEA). Operando nuclear magnetic resonance (NMR) study showed in situ formation of N-formamide intermediate, which underwent further hydrogenation to form methane and other higher hydrocarbons. Technoeconomic analyses (TEA) showed that the proposed integrated process can potentially improve the thermal efficiency by 5 % and reduce the total capital investment and minimum synthetic natural gas (SNG) selling price by 32 % and 12 %, respectively, compared to the conventional Sabatier process, highlighting the energetic and economic benefits of integrated capture and conversion. Methane derived from CO2 and renewable H2 sources is an attractive fuel, and it has great potential as a renewable hydrogen carrier as an environmentally responsible carbon capture and utilization approach.
- Burton, Sarah D.,Dagle, Robert A.,Heldebrant, David J.,Jiang, Yuan,Kothandaraman, Jotheeswari,Saavedra Lopez, Johnny,Walter, Eric D.
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p. 4812 - 4819
(2021/10/07)
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- SELECTIVE PRODUCTION OF METHANOL AND ETHANOL FROM CO HYDROGENATION
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A method for producing methanol and ethanol is disclosed. The method can include contacting a gaseous stream comprising carbon monoxide (CO) and hydrogen (H22) with a crystalline cobalt molybdenum catalyst under conditions suitable to produce a products stream comprising methanol and ethanol from the CO and H22.
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Paragraph 0036-0037
(2021/02/12)
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- Dimethyl ether synthesis process exploiting CO-rich gas
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The present invention relates to a converter gas (Lintz-Donawiaz convert Gas) that is an excess of carbon monoxide-containing gas such as iron-iron enriched gas. Dimethyl ether using LDG). dimethyl ether. DME) A synthesis process. Is a process for producing dimethyl ether, which is a high-value product with high selectivity, utilizing whole gas as a source gas.
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Paragraph 0055-0059
(2021/06/09)
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- Visualizing Element Migration over Bifunctional Metal-Zeolite Catalysts and its Impact on Catalysis
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The catalytic performance of composite catalysts is not only affected by the physicochemical properties of each component, but also the proximity and interaction between them. Herein, we employ four representative oxides (In2O3, ZnO, Cr2O3, and ZrO2) to combine with H-ZSM-5 for the hydrogenation of CO2 to hydrocarbons directed by methanol intermediate and clarify the correlation between metal migration and the catalytic performance. The migration of metals to zeolite driven by the harsh reaction conditions can be visualized by electron microscopy, meanwhile, the change of zeolite acidity is also carefully characterized. The protonic sites of H-ZSM-5 are neutralized by mobile indium and zinc species via a solid ion-exchange mechanism, resulting in a drastic decrease of C2+ hydrocarbon products over In2O3/H-ZSM-5 and ZnO/H-ZSM-5. While, the thermomigration ability of chromium and zirconium species is not significant, endowing Cr2O3/H-ZSM-5 and ZrO2/H-ZSM-5 catalysts with high selectivity of C2+ hydrocarbons.
- Cheng, Kang,Wang, Genyuan,Wang, Ye,Wang, Yuhao,Zhang, Qinghong,de Jong, Krijn P.,van der Wal, Lars I.
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supporting information
p. 17735 - 17743
(2021/07/02)
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- Promotion effect of iron addition on the structure and CO2 hydrogenation performance of Attapulgite/Ce0.75Zr0.25O2 nanocomposite supported Cu-ZnO based catalyst
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A series of CZFxK/ATP-CZO catalysts (x= 0, 0.3, 0.5, 1.0, 1.5 and 2.0) are applied to clarify the effects of the iron addition on the catalytic performance of CO2 hydrogenation to CH3OH. The physicochemical properties and catalytic mechanism were investigated by N2 adsorption/desorption, XRD, TEM, N2O chemisorption, XPS, H2-TPR, CO2-TPD and in-situ DRIFT techniques. The best catalytic performance is achieved over CZF0.5K/ATP-CZO catalyst, exhibiting XCO2 = 17.5%, STYCH3OH = 0.108 g/gcat.?h and STYCO = 0.146 g/gcat.?h (T = 320°C, P = 6 MPa). The formation of dispersed surface metallic Cu species and larger number of surface adsorbed and lattcie oxygen species and ZnO-CZO interfaces are detected over CZF0.5K/ATP-CZO due to stronger interaction between dispersed metallic Cu particles on ZnO-Fe nano-cluster and ATP-CZO composite, resulting in the superior activation ability for H2 and CO2 respectively. Additionally, the evidence is provided by in-situ DRIFTS under the activity test temperature (320°C) that HCOO? and CO* species are preferable for accumulating over CZK/ATP-CZO catalyst without Fe addition while medium Fe-modified CZFxK/ATP-CZO catalysts (CZF0.3K/ATP-CZO, CZF0.5K/ATP-CZO) catalysts are benefitial to promote the transformation of HCOO? species to CH3OH. These excessive Fe-modified CZFxK/ATP-CZO catalysts (CZF1.0K/ATP-CZO, CZF2.0K/ATP-CZO) are more easily to produce CH4 via formate pathway (CO2* → HCOO* → HCO* → CH* → CH4*). The abundant population and high transformation activity of formate intermediate species over CZF0.5K/ATP-CZO give a strong positive effect on the CO2 hydrogenation to methanol performance.
- Chen, Xinde,Ding, Shuai,Guo, Haijun,Peng, Fen,Wang, Can,Xiong, Lian,Yao, Shimiao,Zhang, Hairong
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- In situ Irradiated XPS Investigation on S-Scheme TiO2@ZnIn2S4 Photocatalyst for Efficient Photocatalytic CO2 Reduction
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Reasonable design of efficient hierarchical photocatalysts has gained significant attention. Herein, a step-scheme (S-scheme) core-shell TiO2@ZnIn2S4 heterojunction is designed for photocatalytic CO2 reduction. The optimized sample exhibits much higher CO2 photoreduction conversion rates (the sum yield of CO, CH3OH, and CH4) than the blank control, i.e., ZnIn2S4 and TiO2. The improved photocatalytic performance can be attributed to the inhibited recombination of photogenerated charge carriers induced by S-scheme heterojunction. The improvement is also attributed to the large specific surface areas and abundant active sites. Meanwhile, S-scheme photogenerated charge transfer mechanism is testified by in situ irradiated X-ray photoelectron spectroscopy, work function calculation, and electron paramagnetic resonance measurements. This work provides an effective strategy for designing highly efficient heterojunction photocatalysts for conversion of solar fuels.
- Wang, Libo,Cheng, Bei,Zhang, Liuyang,Yu, Jiaguo
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- CO2 hydrogenation to methanol over Rh/In2O3 catalyst
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CO2 hydrogenation to methanol is of great significance for the emission control and utilization of CO2. In this work, the Rh/In2O3 catalyst with high Rh dispersion was prepared by deposition-precipitation method. The catalyst characterization demonstrates that the highly dispersed Rh species promotes the dissociative adsorption and spillover of hydrogen, which further enhances not only the formation of surface oxygen vacancy of In2O3 but also CO2 adsorption and activation. Enhanced activity was thereby achieved for selective hydrogenation of CO2 to methanol. A CO2 conversion of 17.1 % with methanol selectivity of 56.1 %, corresponding to a methanol space time yield (STY) up to 0.5448 gMeOH h?1 gcat?1, has been obtained under 300 °C, 5 MPa, 76/19/5 of H2/CO2/N2 (molar ratio) and 21,000 cm3 h?1 g?1 of gas hourly space velocity. Under the same reaction condition, the CO2 conversion is only 9.4 % with a methanol STY of 0.3402 gMeOH h?1 gcat?1 over In2O3. The methanol selectivity can be even higher than 70 % at the reaction temperatures below 275 °C for Rh/In2O3 catalyst.
- Wang, Jing,Sun, Kaihang,Jia, Xinyu,Liu, Chang-jun
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p. 341 - 347
(2020/05/18)
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- CO2 hydrogenation to methanol on Ga2O3-Pd/SiO2 catalysts: Dual oxide-metal sites or (bi)metallic surface sites?
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A series of palladium (2 wt.%) catalysts supported on silica (301 m2/g) and loaded with increasing amount of gallium – ratio of Ga/Pd = 2, 4 and 8 atom/atom – were investigated for CO2 hydrogenation to methanol. The turnover frequency to methanol (H2/CO2 = 3; 523 K, 3 MPa), based on surface palladium, showed a 200-fold enhancement as compared to the monometallic Pd/SiO2 catalyst. Additionally, the apparent activation energy for methanol synthesis decreased from 60 kJ/mol on Pd/SiO2 to ～40 kJ/mol on the supported Ga-Pd catalysts. Characterization of the Pd-Ga catalyst series by X-ray absorption spectroscopy and high resolution transmission electron microscopy indicates the formation of Pd2Ga bimetallic nanoparticles partially covered by a thin layer of Ga2O3 on the silica surface. In situ infrared spectroscopy was employed to examine the reaction mechanism during the CO2 adsorption and hydrogenation at 0.7 MPa. It is proposed a bifunctional pathway where the carbonaceous species bound to the gallium oxide surface are hydrogenated, stepwise, to formate and methoxy groups by atomic hydrogen, which spillovers from the Pd-Ga bimetallic nanoparticles.
- Collins, Sebastián E.,Baltanás, Miguel A.,Delgado, Juan José,Borgna, Armando,Bonivardi, Adrian L.
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p. 154 - 162
(2020/08/11)
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- Lewis Acid Strength of Interfacial Metal Sites Drives CH3OH Selectivity and Formation Rates on Cu-Based CO2 Hydrogenation Catalysts
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CH3OH formation rates in CO2 hydrogenation on Cu-based catalysts sensitively depend on the nature of the support and the presence of promoters. In this context, Cu nanoparticles supported on tailored supports (highly dispersed M on SiO2; M=Ti, Zr, Hf, Nb, Ta) were prepared via surface organometallic chemistry, and their catalytic performance was systematically investigated for CO2 hydrogenation to CH3OH. The presence of Lewis acid sites enhances CH3OH formation rate, likely originating from stabilization of formate and methoxy surface intermediates at the periphery of Cu nanoparticles, as evidenced by metrics of Lewis acid strength and detection of surface intermediates. The stabilization of surface intermediates depends on the strength of Lewis acid M sites, described by pyridine adsorption enthalpies and 13C chemical shifts of -OCH3 coordinated to M; these chemical shifts are demonstrated here to be a molecular descriptor for Lewis acid strength and reactivity in CO2 hydrogenation.
- Noh, Gina,Lam, Erwin,Bregante, Daniel T.,Meyet, Jordan,?ot, Petr,Flaherty, David W.,Copéret, Christophe
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supporting information
p. 9650 - 9659
(2021/03/22)
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- Design of highly stable MgO promoted Cu/ZnO catalyst for clean methanol production through selective hydrogenation of CO2
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The synergistic interaction between small Cu particles and MgO/ZnO-supported catalysts, synthesized by the hydrothermal method, show a very high methanol production rate (0.0063 mol gCu?1 h?1). High Cu dispersion and large Cu surface area in the hydrothermal synthesized Cu/MgO/ZnO catalyst postulated to be the reason for high activity. The formation of defected ZnO crystals with Mg atoms provided a better adsorption site for CO2 (near Mg atom), whereas Cu-ZnO interface sites are responsible for the activation of CO2. 20 wt% loaded MgO catalyst showed preference to selective CO2 hydrogenation pathway producing clean methanol with > 99 % selectivity. In addition, Density Functional Theory (DFT) studies revealed that the basic nature of the MgO support can be the probable reason for the higher CO2 adsorption at the Cu-MgO interface compared to the Cu-ZnO interface. Cu13/MgO/ZnO (100) surface model is studied to understand the promoting effect of MgO on CO2 adsorption.
- Bal, Rajaram,Bordoloi, Ankur,Gupta, Shelaka,Khan, Tuhin Suvra,Paul, Bappi,Poddar, Mukesh Kumar,Samanta, Chanchal,Sasaki, Takehiko,Sharma, Sachin Kumar,Singha, Rajib Kumar
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- Understanding the Origin of Structure Sensitivity in Nano Crystalline Mixed Cu/Mg?Al Oxides Catalyst for Low-Pressure Methanol Synthesis
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Cu nanoparticles of size 5–10 nm supported on Mg?Al mixed oxide were prepared by the sol-gel method. Cu loading was varied from 2.5 to 10 wt % on the support to investigate the effect on particle size and activity/selectivity of the catalyst. The Cu/Mg?Al catalysts containing small copper nanoparticles favor high selectivity of methanol, while the rate of CO formation was higher for larger copper particles. The high methanol selectivity (～99 %) and methanol formation rate (0.016 mol gCu?1 h?1) over the 4.8Cu/Mg?Al catalyst was due to the combined effect of the presence of high Cu dispersion, Cu surface area, and strong interaction between small Cu particles with Mg?Al support. The high stability of the catalyst was attributed to the strong binding of the Cu cluster (?179.7 kJ/mol) to the MgO/γ-Al2O3 support, as shown by the DFT study. Additionally, the adsorption energy calculated using DFT showed preferential adsorption of CO2 and H2 at the Cu/MgO(100) active site (?120.9 kJ/mol, ?130.4 kJ/mol) compared to the Cu/γ-Al2O3(100) (?64.2 kJ/mol, ?85.7 kJ/mol)active site. The high selectivity of the catalyst towards methanol can be attributed to the higher stability of the formate (HCOO) intermediate (?257.2 kJ/mol) compared to the carboxylate (COOH) intermediate (?131.0 kJ/mol).
- Sharma, Sachin Kumar,Paul, Bappi,Bhanja, Piyali,Poddar, Mukesh Kumar,Samanta, Chanchal,Khan, Tuhin Suvra,Haider, M. Ali,Bal, Rajaram
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p. 3290 - 3302
(2021/06/14)
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- Engineering the Cu/Mo2CTx (MXene) interface to drive CO2 hydrogenation to methanol
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Development of efficient catalysts for the direct hydrogenation of CO2 to methanol is essential for the valorization of this abundant feedstock. Here we show that a silica-supported Cu/Mo2CTx (MXene) catalyst achieves a higher intrinsic methanol formation rate per mass Cu than the reference Cu/SiO2 catalyst with a similar Cu loading. The Cu/Mo2CTx interface can be engineered due to the higher affinity of Cu for the partially reduced MXene surface (in preference to the SiO2 surface) and the mobility of Cu under H2 at 500 °C. With increasing reduction time, the Cu/Mo2CTx interface becomes more Lewis acidic due to the higher amount of Cu+ sites dispersed onto the reduced Mo2CTx and this correlates with an increased rate of CO2 hydrogenation to methanol. The critical role of the interface between Cu and Mo2CTx is further highlighted by density functional theory calculations that identify formate and methoxy species as stable reaction intermediates. [Figure not available: see fulltext.]
- Abdala, Paula M.,Chen, Zixuan,Comas-Vives, Aleix,Copéret, Christophe,Donat, Felix,Fedorov, Alexey,Kierzkowska, Agnieszka,Kuznetsov, Denis A.,López, Anna Vidal,López, Estefanía Díaz,Lam, Erwin,Müller, Christoph R.,Mance, Deni,Tsoukalou, Athanasia,Willinger, Elena,Zhou, Hui
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p. 860 - 871
(2021/10/27)
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- Gas-phase oxidative carbonylation of methane to acetic acid over zeolites
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Gas-phase oxidative carbonylation of methane was first performed on ZSM-5 zeolites. The addition of water vapor to a mixture of carbonylation gases leads to a multiple (by two orders of magnitude) increase in acetic acid yield. Zeolites with high acidity, primarily Br?nsted acidity, favor the target product formation.
- Ezhova, Natalia N.,Golubev, Konstantin B.,Kolesnichenko, Natalia N.,Yashina, Olga V.
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p. 712 - 714
(2021/11/26)
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- Nonuniform Electric Field-Enhanced In-Source Declustering in High-Pressure Photoionization/Photoionization-Induced Chemical Ionization Mass Spectrometry for Operando Catalytic Reaction Monitoring
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Photoionization mass spectrometry (PI-MS) is a powerful and highly sensitive analytical technique for online monitoring of volatile organic compounds (VOCs). However, due to the large difference of PI cross sections for different compounds and the limitation of photon energy, the ability of lamp-based PI-MS for detection of compounds with low PI cross sections and high ionization energies (IEs) is insufficient. Although the ion production rate can be improved by elevating the ion source pressure, the problem of generating plenty of cluster ions, such as [MH]+·(H2O)n (n = 1 and 2) and [M2]+, needs be solved. In this work, we developed a new nonuniform electric field high-pressure photoionization/photoionization-induced chemical ionization (NEF-HPPI/PICI) source with the abilities of both HPPI and PICI, which was accomplished through ion-molecule reactions with high-intensity H3O+ reactant ions generated by photoelectron ionization (PEI) of water molecules. By establishing a nonuniform electric field in a three-zone ionization region to enhance in-source declustering and using 99.999% helium as the carrier gas, not only the formation of cluster ions was significantly diminished, but the ion transmission efficiency was also improved. Consequently, the main characteristic ion for each analyte both in HPPI and PICI occupied more than 80%, especially [HCOOH·H]+ with a yield ratio of 99.2% for formic acid. The analytical capacity of this system was demonstrated by operando monitoring the hydrocarbons and oxygenated VOC products during the methanol-to-olefins and methane conversion catalytic reaction processes, exhibiting wide potential applications in process monitoring, reaction mechanism research, and online quality control.
- Wan, Ningbo,Jiang, Jichun,Hu, Fan,Chen, Ping,Zhu, Kaixin,Deng, Dehui,Xie, Yuanyuan,Wu, Chenxin,Hua, Lei,Li, Haiyang
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p. 2207 - 2214
(2021/02/03)
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- Direct Partial Oxidation of Methane Catalyzed by an in Situ Generated Active Au(III) Complex at Low Temperature in Ionic Liquids
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An in situ generated AuIII catalyst is found to catalyze the direct oxidation of CH4 to C1 oxygenates in 1-ethylimidazolium bis-(trifluoromethylsulfonyl)amide ([Eim][NTf2]) at 90 °C. The formation of 13CH3OH and H13COOH from 13CH4 as a feed verifies the CH4 oxidation to CH3OH and HCOOH. Ionic liquids (ILs) with a wide range of structural types as potential reaction media and a number of solid, liquid, and gaseous oxidants are screened in a temperature range of 90-200 °C. Among the ILs and the oxidants, [Eim][NTf2] and hydrogen peroxide (H2O2) are identified to be compatible as the stable solvent and the most efficient oxidant, respectively, for the selective oxidation of CH4 to C1 oxygenates, with CH3OH as the primary product. An AuIII-CH4 H-bonding structure, produced in situ by adding two molar equivalent of silver trifluoromethanesulfonate (AgOTf) to the AuCl3(phen) (phen=phenanthroline) precursor under high CH4 pressure, forms a resting state of the AuIII catalyst, which produces CH3OH in the presence of H2O. After each catalytic turnover, AuI is oxidized by H2O2 to regenerate the active AuIII state. In the absence of CH4, unstable AuCl(OTf)2(phen) rapidly forms an orange-colored precipitate that shows no activity in CH4 activation. CH3OH overoxidation to HCOOH was dominantly catalyzed by potent Au0 species as a result of AuI disproportionation, which is the detrimental catalyst deactivation mechanism. Increasing CH4 pressure and H2O2 concentration successfully enhances the catalyst lifetime and significantly improves the CH4 oxidation efficiency with the improved CH3OH/HCOOH ratio. Density functional theory (DFT) calculations showed that (1) a C-H bond in CH4 was activated by forming AuIII-CH3 with a free energy barrier of 26.7 kcal/mol in a six-membered ring transition state and (2) AuIII-CH3 was functionalized to CH3OH by nucleophilic H2O with a free energy barrier of 29.1 kcal/mol or by MeOTf reductive elimination with a free energy barrier of 21.1 kcal/mol.
- Huang, Tingyu,Xu, Zhanwei,Yan, Peifang,Liu, Xiumei,Fan, Hongjun,Zhang, Z. Conrad
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p. 370 - 382
(2021/02/27)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
- -
-
Paragraph 0111
(2021/03/19)
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- A chemiresistive methane sensor
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A chemiresistive sensor is described for the detection of methane (CH4), a potent greenhouse gas that also poses an explosion hazard in air. The chemiresistor allows for the low-power, low-cost, and distributed sensing of CH4 at room temperature in air with environmental implications for gas leak detection in homes, production facilities, and pipelines. Specifically, the chemiresistors are based on single-walled carbon nanotubes (SWCNTs) noncovalently functionalized with poly(4-vinylpyridine) (P4VP) that enables the incorporation of a platinum-polyoxometalate (Pt-POM) CH4 oxidation precatalyst into the sensor by P4VP coordination. The resulting SWCNT-P4VP-Pt-POM composite showed ppm-level sensitivity to CH4 and good stability to air as well as time, wherein the generation of a high-valent platinum intermediate during CH4 oxidation is proposed as the origin of the observed chemiresistive response. The chemiresistor was found to exhibit selectivity for CH4 over heavier hydrocarbons such as n-hexane, benzene, toluene, and o-xylene, as well as gases, including carbon dioxide and hydrogen. The utility of the sensor in detecting CH4 using a simple handheld multimeter was also demonstrated.
- Bezdek, Máté J.,Luo, Shao-Xiong Lennon,Ku, Kang Hee,Swager, Timothy M.
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- METHOD FOR DIRECTLY PREPARING DIMETHYL ETHER BY SYNTHESIS GAS
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Provided is a method for directly preparing dimethyl ether by synthesis gas, the method comprises: the synthesis gas is passed through a reaction zone carrying a catalyst, and reacted under the reaction conditions sufficient to convert at least a portion of the raw materials to obtain the reaction effluent comprising dimethyl ether; and the dimethyl ether is separated from the reaction effluent, wherein the catalyst is zinc aluminum spinel oxide. In the present invention, only one zinc aluminum spinel oxide catalyst is used, which can make the synthesis gas to highly selectively form dimethyl ether, the catalyst has good stability and can be regenerated. The method of the present invention realizes the production of dimethyl ether in one step by the synthesis gas, and reduces the large energy consumption problem caused by step-by-step production.
- -
-
Paragraph 0040; 0041; 0044
(2021/08/13)
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- Oxidation of methane to methanol over Pd@Pt nanoparticles under mild conditions in water
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Direct methane oxidation into oxygen-containing chemicals under mild conditions has sparked increasing interest. Here, we report Pd@Pt core-shell nanoparticles that efficiently catalyse the direct oxidation of CH4to CH3OH in water using H2O2as an oxidant under mild conditions. The catalyst presents a methanol productivity of up to 89.3 mol kgcatalyst?1h?1with a high selectivity of 92.4% after 30 min at 50 °C, thus outperforming most of the previously reported catalysts. Electron-enriched Pt species in the Pd@Pt nanoparticles were identified by structural and electronic analysis. Pd in the core donates electrons to Pt, leading to higher rates of methane activation. Based on the results of control experiments and kinetic analysis, a consecutive oxidation pathwayviaa radical mechanism is proposed, which includes initial formation of CH3OOH and CH3OH followed by further oxidation of CH3OH to HCHO, HCOOH, and CO2
- Chen, Jianjun,Chen, Yaoqiang,Collière, Vincent,Lecante, Pierre,Peres, Laurent,Philippot, Karine,Wang, Sikai,Yan, Ning
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p. 3493 - 3500
(2021/06/06)
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- Neighboring Zn-Zr Sites in a Metal-Organic Framework for CO2Hydrogenation
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ZrZnOx is active in catalyzing carbon dioxide (CO2) hydrogenation to methanol (MeOH) via a synergy between ZnOx and ZrOx. Here we report the construction of Zn2+-O-Zr4+ sites in a metal-organic framework (MOF) to reveal insights into the structural requirement for MeOH production. The Zn2+-O-Zr4+ sites are obtained by postsynthetic treatment of Zr6(μ3-O)4(μ3-OH)4 nodes of MOF-808 by ZnEt2 and a mild thermal treatment to remove capping ligands and afford exposed metal sites for catalysis. The resultant MOF-808-Zn catalyst exhibits >99% MeOH selectivity in CO2 hydrogenation at 250 °C and a high space-time yield of up to 190.7 mgMeOH gZn-1 h-1. The catalytic activity is stable for at least 100 h. X-ray absorption spectroscopy (XAS) analyses indicate the presence of Zn2+-O-Zr4+ centers instead of ZnmOn clusters. Temperature-programmed desorption (TPD) of hydrogen and H/D exchange tests show the activation of H2 by Zn2+ centers. Open Zr4+ sites are also critical, as Zn2+ centers supported on Zr-based nodes of other MOFs without open Zr4+ sites fail to produce MeOH. TPD of CO2 reveals the importance of bicarbonate decomposition under reaction conditions in generating open Zr4+ sites for CO2 activation. The well-defined local structures of metal-oxo nodes in MOFs provide a unique opportunity to elucidate structural details of bifunctional catalytic centers.
- An, Bing,Cao, Yonghua,Dai, Yiheng,Li, Zhe,Lin, Wenbin,Wang, Cheng,Wang, Wangyang,Zeng, Lingzhen,Zhang, Jingzheng
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supporting information
p. 8829 - 8837
(2021/06/28)
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- Synthesis of Methanol from СО2 on Cu–Zn/xAl2O3–(1 – x)SiO2 Catalysts. Effect of Support Composition
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Abstract: A comparative study of the catalytic properties of Cu–Zn catalysts on supports of various compositions in methanol synthesis by hydrogenation of CO2 has been performed. The commercial adsorbents: Al2O3, Al2O3 with SiO2 addition, SiO2 with Al2O3 addition, and SiO2 (all from Saint Gobain) were used as supports. All these catalysts were shown to be effective in the methanol synthesis. The highest methanol selectivity was observed for the sample with the Al2O3 support. In the temperature range of 170–210°C, the methanol selectivity for this catalyst was over 96%. The highest efficiency with respect to methanol, especially at temperatures above 210°C, was observed for the sample on the Al2O3 support with SiO2 addition.
- Borkov, S. A.,Evdokimenko, N. D.,Kim, K. O.,Kustov, A. L.,Pribytkov, P. V.,Tedeeva, M. A.
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p. 2422 - 2425
(2021/12/13)
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- Cu/ZnOx@UiO-66 synthesized from a double solvent method as an efficient catalyst for CO2hydrogenation to methanol
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Cu/ZnOxin UiO-66, namely, Cu/ZnOx@UiO-66, was synthesized using a double solvent method with controllable Cu/Zn ratios. Due to the ultra-small nanoparticles confined in the metal-organic framework and the special Cu/ZnOxinterface, this composite Cu/ZnOx@UiO-66 catalyst showed excellent performance for CO2hydrogenation to methanol. In fact, the space-time yield of methanol is enhanced by 5.5 and 8.5 times compared with those on the commercialized Cu/ZnO/Al2O3and the Cu/ZnOx@UiO-66 prepared with the traditional impregnation method. Furthermore, the catalyst shows good stability over a period of 100 h on stream.
- Cheng, Enping,Ding, Heng,Hao, Yiming,Hong, Yanzhen,Li, Jun,Peng, Li,Su, Yuzhong,Wang, Hongtao,Wang, Yanliang,Xu, Yanan,Yang, Dong,Yang, Yang
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p. 4367 - 4375
(2021/07/12)
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- Ultradispersed Mo/TiO2catalysts for CO2hydrogenation to methanol
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Mo/TiO2 catalysts with atomic dispersion of molybdenum appear active and stable in the gas-phase hydrogenation of CO2. A comparison between various titania materials shows a crucial effect of the support surface structure on the methanol yield. Molybdenum supported at low coverage on rutile titania nanorods is the most active and methanol-selective system. From catalyst characterization by aberration-corrected scanning transmission electron microscopy, near-ambient pressure X-ray photoelectron spectroscopy, diffuse reflectance UV-vis spectroscopy, and temperature-programmed techniques, we suggest that the most active catalysts for methanol production involve ultradispersed molybdate species with high reducibility and strong interaction with the rutile support.
- Afanasiev, Pavel,Bahri, Mounib,Cardenas, Luis,Checa, Ruben,Ersen, Ovidiu,Lefkir, Yaya,Len, Thomas,Llorca, Jordi,Morfin, Franck,Pérez Dieste, Virginia,Perret, Noémie,Piccolo, Laurent,Puzenat, Eric,Villar-Garcia, Ignacio J.
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p. 7259 - 7268
(2021/09/28)
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- On the reaction mechanism of MnOx/SAPO-34 bifunctional catalysts for the conversion of syngas to light olefins
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MnOx/SAPO-34 bifunctional catalysts are efficient for the conversion of syngas to light olefins. However, the reaction mechanism is still debated in particular the nature of the intermediate formed on MnOx(ketenevs.methanol). In this study, it was evidenced from catalytic data andin situDRIFT measurements that methanol is a key reaction intermediate produced on MnOxthat synergistically reacts with SAPO-34 to produce light olefins.
- Afanasiev, Pavel,Checa, Ruben,Coudercy, Christophe,L'hospital, Valentin,Le Valant, Anthony,Loridant, Stéphane
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p. 7844 - 7849
(2021/12/27)
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- Highly selective hydrogenation of diesters to ethylene glycol and ethanol on aluminum-promoted CuAl/SiO2 catalysts
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A highly selective CuAl/SiO2 catalyst was prepared for the hydrogenation of dimethyl oxalate (DMO) and ethylene carbonate (EC) to ethanol and ethylene glycol (EG), respectively. Aluminum modified silica sol was used to prepare CuAl/SiO2 catalysts by a hydrothermal method. The catalytic performance of the CuAl/SiO2 catalysts with varying aluminum content was investigated at the conditions of 553 K and 2.5 MPa for DMO hydrogenation, while 453 K and 3 MPa for EC hydrogenation. The results showed that the Cu1.0Al/SiO2 catalyst exhibited the highest selectivity of ethanol (～94 %) in the DMO hydrogenation, while the Cu0.5Al/SiO2 catalyst exhibited the highest selectivity of EG (～95 %) and methanol (65 %) in the EC hydrogenation. Characterizations (e.g., TPD, TPR and XANES) indicated that the moderate aluminum modification on SiO2 in the form of [tbnd]Si–OH–Al bond could not only tune the support acidity to polarize the C[dbnd]O bond of esters, but also intrinsically facilitate the dispersion of Cu active species to activate H2, which thus facilitated the selective hydrogenation reaction to EG, ethanol and methanol.
- Shu, Guoqiang,Ma, Kui,Tang, Siyang,Liu, Changjun,Yue, Hairong,Liang, Bin
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p. 173 - 180
(2020/01/13)
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- Well-defined Cp*Co(III)-catalyzed Hydrogenation of Carbonates and Polycarbonates
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We herein report the catalytic hydrogenation of carbonates and polycarbonates into their corresponding diols/alcohols using well-defined, air-stable, high-valent cobalt complexes. Several novel Cp*Co(III) complexes bearing N,O-chelation were isolated for the first time and structurally characterized by various spectroscopic techniques including single crystal X-ray crystallography. These novel Co(III) complexes have shown excellent catalytic activity to produce value added diols/alcohols from carbonate and polycarbonates through hydrogenation using molecular hydrogen as sole reductant or iPrOH as transfer hydrogenation source. To demonstrate the developed methodology's practical applicability, we have recycled the bisphenol A monomer from compact disc (CD) through hydrogenation under the established reaction conditions using phosphine-free, earth-abundant, air- and moisture-stable high-valent cobalt catalysts.
- Dahiya, Pardeep,Gangwar, Manoj Kumar,Sundararaju, Basker
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p. 934 - 939
(2020/12/15)
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- Integrated capture and conversion of CO2 to methanol or methanol and glycol
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A process for producing methanol includes combining a hydrogenation catalyst, hydrogen, and CO2 with a condensed phase solution comprising an amine under conditions effective to form methanol and water. A process for coproduction of methanol and a glycol includes combining an epoxide, a hydrogenation catalyst, hydrogen, and CO2 with a condensed phase solution comprising an amine under conditions effective to form methanol and a glycol.
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Page/Page column 37-38
(2021/03/31)
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- Facile synthesis of N-doped carbon supported iron species for highly efficient methane conversion with H2O2 at ambient temperature
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A series of N-doped carbon supported highly-dispersed Fe catalysts are prepared, and their catalytic performances for the direct conversion of methane to CH3OH and HCOOH with by-product CO2 are tested at ambient temperature. The nitrogen doping can greatly improve the metal-support interaction, and anchor the Fe species on the support. The catalytic activity of the catalyst is further enhanced by the modification of hydroxylamine hydrochloride. The optimized 2.5 wt%Fe/NC?HH catalyst shows 475 μmol/gcat for CH3OH and 832 μmol/gcat for HCOOH after 1 h reaction. The effect of the type of nitrogen species on the catalytic performance of the catalyst has been studied in detail. In addition, other transition metals (Ni, Co, Cu and Mn) as active centers have been also studied, and none of them is effective for the conversion of methane. Additionally, it is found that the methane conversion over the prepared catalysts proceed via a radical mechanism.
- Zhang, Li,Lin, Yan
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- Lanthanum modified Fe-ZSM-5 zeolites for selective methane oxidation with H2O2
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Selective partial oxidation of methane to methanol under ambient conditions is a great challenge in chemistry. Iron modified ZSM-5 catalysts are shown to be effective for this reaction using H2O2as the oxidant. However, the high consumption of H2O2over this catalyst presents a major disadvantage. Here we report a lanthanum modified Fe-ZSM-5 (LaFe-ZSM-5) catalyst for enhanced selective methane oxidation with suppressed H2O2consumption. Using 0.5 wt% LaFe-ZSM-5 pretreated with H2the productivity of primary oxygenated products (CH3OH, CH3OOH, HCOOH) is 3200 mol kgLaFe?1h?1in 0.1 M H2O2, with a selectivity of 98.9% to primary oxygenated products. The productivity is increased to 11?460 mol kgLaFe?1h?1in 0.5 M H2O2. Compared with Fe-ZSM-5, LaFe-ZSM-5 uses 31% less H2O2for obtaining per mol of product under the same conditions.In situDRIFT spectroscopy and solid state MAS NMR revealed the high H2O2consumption in ZSM-5 based catalyst maybe closely related to the acidity of strong Br?nsted acid sites (Si(OH)Al). The La modified ZSM-5 catalyst can decrease the acidity of the strong Br?nsted acid sites and this suppresses the decomposition of H2O2
- Barnes, Alexandra J.,Bere, Takudzwa,Dummer, Nicholas F.,Gong, Xiaoxiao,Hutchings, Graham J.,Lewis, Richard J.,Morgan, David J.,Richards, Nia,Shaw, Greg,Sun, Songmei
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p. 8052 - 8064
(2021/12/27)
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- H2O-Built Proton Transfer Bridge Enhances Continuous Methane Oxidation to Methanol over Cu-BEA Zeolite
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Direct oxidation of methane to methanol (DMTM) is a big challenge in C1 chemistry. We present a continuous N2O-DMTM investigation by simultaneously introducing 10 vol % H2O into the reaction system over Cu-BEA zeolites. Combining a D2O isotopic tracer technique and ab initio molecular dynamics (AIMD) simulation, we for the first time demonstrate that the H2O molecules can participate in the reaction through a proton transfer route, wherein the H2O molecules can build a high-speed proton transfer bridge between the generated moieties of CH3? and OH? over the evolved mono(μ-oxo) dicopper ([Cu-O-Cu]2+) active site, thereby pronouncedly boosting the CH3OH selectivity (3.1→71.6 %), productivity (16.8→242.9 μmol gcat?1 h?1) and long-term reaction stability (10→70 h) relative to the scenario of absence of H2O. Unravelling the proton transfer of H2O over the dicopper [Cu-O-Cu]2+ site would substantially contribute to highly efficient catalyst designs for the continuous DMTM.
- Chen, Biaohua,Dai, Chengna,Li, Yan,Liu, Ning,Wu, Bin,Xu, Ruinian,Yu, Gangqiang,Zhang, Jie
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supporting information
p. 16634 - 16640
(2021/06/23)
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- Citric acid modified Ni3P as a catalyst for aqueous phase reforming and hydrogenolysis of glycerol to 1,2-PDO
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Citric acid (CA) modified Ni3P catalysts with small particle sizes were prepared by H2 temperature-programmed reduction (H2-TPR) of the precursors, which were prepared by co-precipitation with Ni(NO3)2·6H2O and (NH4)2HPO4, using citric acid as the chelating agent and calcining under a N2 atmosphere. The catalytic activity of the prepared catalysts was tested in the aqueous phase reforming (APR) and hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). The effects of the CA/Ni molar ratio and reaction conditions (temperature, pressure, and time) on APR and hydrogenolysis of glycerol were investigated. The CA(1)-Ni3P catalyst exhibited the best performance at 220 °C, 0.5 MPa N2, and 8 h with 74.6% glycerol conversion and 43.2% selectivity of 1,2-PDO. The prepared CA(x)-Ni3P catalysts were characterized by XRD, N2 adsorption, Raman spectroscopy, CO-chemisorption and TEM. The addition of CA significantly enhanced the dispersion of Ni species in the precursors and enlarged the surface area of the catalyst. The residual carbonaceous species after calcination in N2 prevented the aggregation of Ni3P particles and promoted the reduction of the precursors. Compared with the unmodified Ni3P and CA(x)-Ni3P calcined in air, the CA(x)-Ni3P calcined in N2 with a smaller average particle size exhibited higher catalytic activities.
- Hu, Tianyu,Liu, Bingyu,Liu, Shan,Liu, Ying-Ya,Sun, Zhichao,Wang, Anjie,Wang, Yao,Yu, Zhiquan
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p. 21725 - 21731
(2021/12/13)
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- Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
- Liu, Xin,Werner, Thomas
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p. 10590 - 10597
(2021/08/20)
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- GNCC AND/OR PCC AS A CATALYTIC CARRIER FOR METAL SPECIES
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The present invention refers to a catalytic system comprising a transition metal compound on a solid carrier, wherein the content of the transition metal compound on the surface of the solid carrier is from 0.1 to 30 wt.-%, based on the dry weight of the solid carrier. Furthermore, the present invention refers to a method for manufacturing the catalytic system, the use of the inventive catalytic system in a chemical reaction, the use of a solid carrier loaded with a transition metal compound as a catalyst and to granules mouldings or extrudates comprising the catalytic system.
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Page/Page column 31-32
(2021/04/02)
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- Ternary ZnO/CuO/Zeolite composite obtained from volcanic ash for photocatalytic CO2 reduction and H2O decomposition
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An n-p heterojunction based on ZnO/CuO supported in a zeolitic framework (ZF) was designed to produce solar fuels from H2O decomposition and CO2 conversion. ZF was synthesized from volcanic ashes by an alternative microwave-hydrothermal method using a biodegradable template for its formation. The framework resulted in NaAlSiO4 (NAS) with a high surface area and a morphology composed of circular channels of 50 nm. Incorporating the ZnO/CuO heterostructure in the NAS channels resulted in an improved light-absorption, more efficient charge transfer, nanostructure morphology, and more active sites available for the CO2 adsorption and photocatalytic reactions. The activities for H2 and light-hydrocarbons (HCOOH, HCOH, and CH3OH) evolution were evaluated in the photocatalytic water-splitting and CO2 reduction under UVA irradiation, respectively. The ZnO/CuO/NAS composite exhibited a remarkably higher H2 (187 μmol/g) and HCOOH (2721 μmol/g) evolution after 3 h of irradiation. These results were related to the synergistic effect among ZnO, CuO, and NAS framework. A mechanism of the photocatalytic reaction was proposed.
- Luévano-Hipólito,Torres-Martínez, Leticia M.,Fernández-Trujillo
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- Gas Phase Glycerol Valorization over Ceria Nanostructures with Well-Defined Morphologies
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Glycerol solutions were vaporized and reacted over ceria catalysts with different morphologies to investigate the relationship of product distribution to the surface facets exposed, particularly, the yield of bio-renewable methanol. Ceria was prepared with cubic, rodlike, and polyhedral morphologies via hydrothermal synthesis by altering the concentration of the precipitating agent or synthesis temperature. Glycerol conversion was found to be low over the ceria with a cubic morphology, and this was ascribed to both a low surface area and relatively high acidity. Density functional theory calculations also showed that the (100) surface is likely to be hydroxylated under reaction conditions which could limit the availability of basic sites. Methanol space-time-yields over the polyhedral ceria samples were more than four times that for the cubic material at 400 °C, where 201 g of methanol was produced per hour per kilogram of the catalyst. Under comparable glycerol conversions, we show that the rodlike and polyhedral catalysts produce a major intermediate to methanol, hydroxyacetone (HA), with a selectivity of ca. 45%, but that over the cubic sample, this was found to be 15%. This equates to a 13-fold increase in the space-time-yield of HA over the polyhedral samples compared to the cubes at 320 °C. The implications of this difference are discussed with respect to the reaction mechanism, suggesting that a different mechanism dominates over the cubic catalysts to that for rodlike and polyhedral catalysts. The strong association between exposed surface facets of ceria to high methanol yields is an important consideration for future catalyst design in this area.
- Smith, Louise R.,Sainna, Mala A.,Douthwaite, Mark,Davies, Thomas E.,Dummer, Nicholas F.,Willock, David J.,Knight, David W.,Catlow, C. Richard A.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 4893 - 4907
(2021/05/04)
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- Investigation on the promotional role of Ga2O3on the CuO-ZnO/HZSM-5 catalyst for CO2hydrogenation
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Dimethyl ether (DME) can be directly synthesized from carbon dioxide and hydrogen by mixing methanol synthesis catalysts and methanol dehydration catalysts. The activity and selectivity of the catalyst can be greatly affected by the promoter; herein, we presented a series of CuO-ZnO-Ga2O3/HZSM-5 hybrid catalysts, which were prepared by the coprecipitation method. The effect of the Ga2O3 content on the structure and performance of the Ga-promoted Cu-ZnO/HZSM-5 based catalysts was thoroughly investigated. The results showed that the addition of Ga2O3 significantly increased specific surface areas and Cu areas, decreased the size of Cu particles, maintained the proportion of Cu+/Cu0 on the surface of the catalyst, and strengthened the metal-support interaction, resulting in high catalytic performance. This journal is
- Du, Jie,Zhang, Yajing,Wang, Kangjun,Ding, Fu,Jia, Songyan,Liu, Guoguo,Tan, Limei
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p. 14426 - 14433
(2021/05/17)
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- Photoelectrochemical reduction of dissolved carbon dioxide over Ni(OH)2 into organic oxygenates
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Abstract: The hydrothermal method has been used to prepare Ni(OH)2 photocathode. The photoelectrochemical (PEC) reduction of CO2 over Ni(OH)2 has been conducted in 0.2?M LiClO4 in aqueous and N,N-dimethylformamide (DMF) medium under visible light irradiation. The thin film was characterized by XRD, UV–Vis, FTIR, FESEM-EDX, BET analysis, and electrochemical method for the determination of phases, bandgap energy, chemical bonding, surface morphology, elemental compositions, surface area, and electrochemical properties, respectively. Based on UV–Vis spectroscopy, the bandgap energy of Ni(OH)2 was 1.8?eV which enabled efficient visible light absorption for the photoreaction. The photocurrent density in aqueous and DMF solution at 0.2?V (vs. Ag/AgCl) was 24?mA?cm?2 and 5?mA?cm?2, respectively. Acetaldehyde and methanol are the products in aqueous solution, while formic acid and methanol are the products in DMF, after 6?h of photoelectrolysis. The product formations from the photoelectrochemical reduction of dissolved CO2 were 612 and 854?ppm in aqueous and DMF, respectively, where the Faradaic efficiency in aqueous and DMF is 24 and 33%, respectively. Furthermore, throughout the PEC study, the transformation of Ni(OH)2 to NiO plays a significant role in the formation of organic oxygenates from the reduction reaction of CO2. Graphic abstract: [Figure not available: see fulltext.]
- Che Mat, Ahmad Nazeer,Basirun, Wan Jefrey,Shahid, Muhammad Mehmood
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p. 1363 - 1372
(2021/01/07)
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- Catalytic Hydrogenation of CO2to Methanol Using Multinuclear Iridium Complexes in a Gas-Solid Phase Reaction
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We report a novel approach toward the catalytic hydrogenation of CO2 to methanol performed in the gas-solid phase using multinuclear iridium complexes at low temperature (30-80 °C). Although homogeneous CO2 hydrogenation in water catalyzed by amide-based iridium catalysts provided only a negligible amount of methanol, the combination of a multinuclear catalyst and gas-solid phase reaction conditions led to the effective production of methanol from CO2. The catalytic activities of the multinuclear catalyst were dependent on the relative configuration of each active species. Conveniently, methanol obtained from the gas phase could be easily isolated from the catalyst without contamination with CO, CH4, or formic acid (FA). The catalyst can be recycled in a batchwise manner via gas release and filling. A final turnover number of 113 was obtained upon reusing the catalyst at 60 °C and 4 MPa of H2/CO2 (3:1). The high reactivity of this system has been attributed to hydride complex formation upon exposure to H2 gas, suppression of the liberation of FA under gas-solid phase reaction conditions, and intramolecular multiple hydride transfer to CO2 by the multinuclear catalyst.
- Kanega, Ryoichi,Onishi, Naoya,Tanaka, Shinji,Kishimoto, Haruo,Himeda, Yuichiro
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supporting information
p. 1570 - 1576
(2021/02/01)
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- Highly Efficient CO2 Electroreduction to Methanol through Atomically Dispersed Sn Coupled with Defective CuO Catalysts
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Using renewable electricity to drive CO2 electroreduction is an attractive way to achieve carbon-neutral energy cycle and produce value-added chemicals and fuels. As an important platform molecule and clean fuel, methanol requires 6-electron transfer in the process of CO2 reduction. Currently, CO2 electroreduction to methanol suffers from poor efficiency and low selectivity. Herein, we report the first work to design atomically dispersed Sn site anchored on defective CuO catalysts for CO2 electroreduction to methanol. It exhibits high methanol Faradaic efficiency (FE) of 88.6 % with a current density of 67.0 mA cm?2 and remarkable stability in a H-cell, which is the highest FE(methanol) with such high current density compared with the results reported to date. The atomic Sn site, adjacent oxygen vacancy and CuO support cooperate very well, leading to higher double-layer capacitance, larger CO2 adsorption capacity and lower interfacial charge transfer resistance. Operando experiments and density functional theory calculations demonstrate that the catalyst is beneficial for CO2 activation via decreasing the energy barrier of *COOH dissociation to form *CO. The obtained key intermediate *CO is then bound to the Cu species for further reduction, leading to high selectivity toward methanol.
- Chen, Chunjun,Guo, Weiwei,Han, Buxing,Huang, Yuying,Liu, Shoujie,Ma, Jingyuan,Sun, Xiaofu,Tan, Xingxing,Wu, Ruizhi,Yan, Xupeng,Zhang, Jing,Zheng, Lirong,Zhu, Qinggong
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supporting information
p. 21979 - 21987
(2021/08/30)
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- Selective oxidation of methane to methanol using AuPd@ZIF-8
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Selective methane conversion to alcohol derivatives remains an open challenge. Here, bimetallic catalyst, AuPd@ZIF-8, has been synthesized and demonstrated as an excellent catalyst in the presence of H2O2 and O2 under mild
- Sun, Chenghua,Xu, Guowang,Xu, Yongjun,Yu, Aimin
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- CO hydrogenation over K-Co-MoSx catalyst to mixed alcohols: A kinetic analysis
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Higher alcohol synthesis (HAS) from syngas is one of the most promising approaches to produce fuels and chemicals. Our recent investigation on HAS showed that potassium-promoted cobalt-molybdenum sulfide is an effective catalyst system. In this study, the intrinsic kinetics of the reaction were studied using this catalyst system under realistic conditions. The study revealed the major oxygenated products are linear alcohols up to butanol and methane is the main hydrocarbon. The higher alcohol products (C3+) followed an Anderson-Schultz-Flory distribution while the catalyst suppressed methanol and ethanol formation. The optimum reaction conditions were estimated to be at temperature of 340°C, pressure of 117?bar, gas hourly space velocity of 27?000?mL?g–1h–1 and H2/CO molar feed ratio of 1. A kinetic network has been considered and kinetic parameters were estimated by nonlinear regression of the experimental data. The results indicated an increasing apparent activation energy of alcohols with the length of alcohols except for ethanol. The lower apparent activation energy of alcohols compared with hydrocarbon evidenced the efficiency of this catalyst system to facilitate the formation of higher alcohols.
- Negahdar, Leila,Xi, Xiaoying,Zeng, Feng,Winkelman,Heeres, Hero Jan,Palkovits, Regina
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supporting information
p. 419 - 427
(2020/11/30)
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