- An efficient Ni-Mo-K sulfide catalyst doped with CNTs for conversion of syngas to ethanol and higher alcohols
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A type of Ni-Mo-K sulfide catalyst doped with CNTs for conversion of syngas to ethanol and higher alcohols was developed, and displayed high activity and selectivity for direct synthesis of C1-4-alcohols, especially ethanol, from syngas. Over a Ni0.5Mo1K0.5- 15%CNTs catalyst under the reaction conditions of 8.0 MPa and 593 K, the S(total oxy.) reached 64.1% (CO2-free), with the corresponding STY(total oxy.) being 113 mg h-1 g-1. Ethanol was the dominant product, with S(EtOH) and STY(EtOH) reaching 33.1% (CO2-free) and 55.6 mg h-1 g-1, respectively. This STY(EtOH)-value was 1.47 times that (37.9 mg h-1 g-1) of the CNTs-free counterpart under the same reaction conditions. Addition of a minor amount of CNTs to the sulfurized Ni0.5Mo1K0.5 catalyst caused little change in the Ea for the hydrogenation-conversion of syngas. Appropriately reducing CNT's grain-size could improve its capability to adsorb hydrogen, thus increasing CO hydrogenation-conversion, yet did not influence selectivity of the products. The present work demonstrated that CNTs as promoter function through their adsorbing/activating H2 to generate a surface micro-environment with higher stationary-state concentration of H-adspecies on the functioning catalyst. This resulted in a dramatic increase, at the surface of the functioning catalyst, of the molar percentage of catalytically active Mo4+/Mo5+ species in the total amounts of surface Mo. On the other hand, those active H-species adsorbed at the CNTs surface could be readily transferred to NiiMojK k active sites via the CNT-assisted hydrogen spillover. The aforementioned two factors both were conducive to increasing the rate of hydrogenation conversion of syngas.
- Wang, Ji-Jie,Xie, Jian-Rong,Huang, Yan-Hui,Chen, Bing-Hui,Lin, Guo-Dong,Zhang, Hong-Bin
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- Enhanced catalytic activity of Au core Pd shell Pt cluster trimetallic nanorods for CO2 reduction
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Herein, Au core Pd shell Pt cluster nanorods (Au@Pd@Pt NRs) with enhanced catalytic activity were rationally designed for carbon dioxide (CO2) reduction. The surface composition and Pd-Pt ratios significantly influenced the catalytic activity, and the optimized structure had only a half-monolayer equivalent of Pt (Pt = 0.5) with 2 monolayers of Pd, which could enhance the catalytic activity for CO2 reduction by 6 fold as compared to the Pt surface at -1.5 V vs. SCE. A further increase in the loading of Pt actually reduced the catalytic activity; this inferred that a synergistic effect existed among the three different nanostructure components. Furthermore, these Au NRs could be employed to improve the photoelectrocatalytic activity by 30% at -1.5 V due to the surface plasmon resonance. An in situ SERS investigation inferred that the Au@Pd@Pt NRs (Pt = 0.5) were less likely to be poisoned by CO because of the Pd-Pt bimetal edge sites; due to this reason, the proposed structure exhibited highest catalytic activity. These results play an important role in the mechanistic studies of CO2 reduction and offer a new way to design new materials for the conversion of CO2 to liquid fuels.
- He, Lan-Qi,Yang, Hao,Huang, Jia-Jun,Lu, Xi-Hong,Li, Gao-Ren,Liu, Xiao-Qing,Fang, Ping-Ping,Tong, Ye-Xiang
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- Production of bio-ethanol by consecutive hydrogenolysis of corn-stalk cellulose
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Current bio-ethanol production entails the enzymatic depolymerization of cellulose, but this process shows low efficiency and poor economy. In this work, we developed a consecutive aqueous hydrogenolysis process for the conversion of corn-stalk cellulose to produce a relatively high concentration of bio-ethanol (6.1 wt%) without humin formation. A high yield of cellulose (ca. 50 wt%) is extracted from corn stalk using a green solvent (80 wt% 1,4-butanediol) without destroying the structure of the lignin. The first hydrothermal hydrogenolysis step uses a Ni–WOx/SiO2 catalyst to convert the high cumulative concentration of cellulose (30 wt%) into a polyol mixture with a 56.5 C% yield of ethylene glycol (EG). The original polyol mixture is then subjected to subsequent selective aqueous-phase hydrogenolysis of the C–O bond to produce bioethanol (75% conversion, 84 C% selectivity) over the modified hydrothermally stable Cu catalysts. The added Ni component favors the good dispersion of Cu nanoparticles, and the incorporated Au3+ helps to stabilize the active Cu0-Cu+ species. This multi-functional catalytic process provides an economically competitive route for the production of cellulosic ethanol from raw lignocellulose.
- Chu, Dawang,Xin, Yingying,Zhao, Chen
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- Highly Selective Electrochemical Reduction of CO2 to Alcohols on an FeP Nanoarray
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Electrochemical reduction of CO2 into various chemicals and fuels provides an attractive pathway for environmental and energy sustainability. It is now shown that a FeP nanoarray on Ti mesh (FeP NA/TM) acts as an efficient 3D catalyst electrode for the CO2 reduction reaction to convert CO2 into alcohols with high selectivity. In 0.5 m KHCO3, such FeP NA/TM is capable of achieving a high Faradaic efficiency (FECH3OH) up to 80.2 %, with a total FE FECH3OH+C2H5OH of 94.3 % at ?0.20 V vs. reversible hydrogen electrode. Density functional theory calculations reveal that the FeP(211) surface significantly promotes the adsorption and reduction of CO2 toward CH3OH owing to the synergistic effect of two adjacent Fe atoms, and the potential-determining step is the hydrogenation process of *CO.
- Ji, Lei,Li, Lei,Ji, Xuqiang,Zhang, Ya,Mou, Shiyong,Wu, Tongwei,Liu, Qian,Li, Baihai,Zhu, Xiaojuan,Luo, Yonglan,Shi, Xifeng,Asiri, Abdullah M.,Sun, Xuping
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- Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper
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Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50% Faradaic efficiency at -0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a minor product and key intermediate in the electroreduction of CO to ethanol on OD-Cu electrodes. Acetaldehyde is produced with a Faradaic efficiency of ≈5% at -0.33 V (vs. RHE). We show that acetaldehyde forms at low steady-state concentrations, and that free acetaldehyde is difficult to detect in alkaline solutions using NMR spectroscopy, requiring alternative methods for detection and quantification. Our results represent an important step towards understanding the CO reduction mechanism on OD-Cu electrodes.
- Bertheussen, Erlend,Verdaguer-Casadevall, Arnau,Ravasio, Davide,Montoya, Joseph H.,Trimarco, Daniel B.,Roy, Claudie,Meier, Sebastian,Wendland, Jürgen,N?rskov, Jens K.,Stephens, Ifan E. L.,Chorkendorff
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- Photochemical Preparation of Anatase Titania Supported Gold Catalyst for Ethanol Synthesis from CO2 Hydrogenation
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Abstract: Hydrogenation of the greenhouse gas CO2 to higher alcohols through catalysis holds great promise for resource transformation in low-carbon energy supply system, but the efficient and selective synthesis of value-added ethanol by a robust heterogeneous catalyst under relatively mild conditions remains a major challenge. Based on our previous work on Au/TiO2 as an active and selective catalyst for ethanol synthesis, we report here that a facile photochemical route can be used for the preparation of anatase TiO2 supported gold catalyst (Au/a-TiO2) for efficient hydrogenation of CO2. Compared with the conventional deposition-precipitation method requiring strong br?nsted base and flammable H2 gas in the complicated and time-consuming process, the photochemical way for the facile preparation of supported gold catalyst shows the advantages of green and energy-saving. Of significant importance is that an impressive space-time-yield of 869.3?mmol?gAu?1?h?1, high selectivity, and excellent stability can be readily attained at 200?°C and total pressure of 6?MPa. The effects of irradiation time, solvent, and metal loading or Au particle size on ethanol synthesis are systematically investigated. Graphical Abstract: [Figure not available: see fulltext.].
- Wang, Dong,Bi, Qingyuan,Yin, Guoheng,Wang, Peng,Huang, Fuqiang,Xie, Xiaoming,Jiang, Mianheng
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- Hydrolysis and Condensation Reactions of Transition Metal Alkoxides: Calorimetric Study and Evaluation of the Extent of Reaction
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The behavior of titanium and zirconium alkoxides towards complexation and water addition is analyzed through water titration and calorimetric experiments. A simple model is presented, which allows evaluation of the mean hydrolysis and condensation constan
- Blanchard, Juliette,In, Martin,Schaudel, Barbara,Sanchez, Clement
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- Fe/Fe3C Boosts H2O2 Utilization for Methane Conversion Overwhelming O2 Generation
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H2O2 as a well-known efficient oxidant is widely used in the chemical industry mainly because of its homolytic cleavage into .OH (stronger oxidant), but this reaction always competes with O2 generation resulting in H2O2 waste. Here, we fabricate heterogeneous Fenton-type Fe-based catalysts containing Fe-Nx sites and Fe/Fe3C nanoparticles as a model to study this competition. Fe-Nx in the low spin state provides the active site for .OH generation. Fe/Fe3C, in particular Fe3C, promotes Fe-Nx sites for the homolytic cleavages of H2O2 into .OH, but Fe/Fe3C nanoparticles (Fe0 as the main component) with more electrons are prone to the undesired O2 generation. With a catalyst benefiting from finely tuned active sites, 18 % conversion rate for the selective oxidation of methane was achieved with about 96 % selectivity for liquid oxygenates (formic acid selectivity over 90 %). Importantly, O2 generation was suppressed 68 %. This work provides guidance for the efficient utilization of H2O2 in the chemical industry.
- Xing, Yicheng,Yao, Zheng,Li, Wenyuan,Wu, Wenting,Lu, Xiaoqing,Tian, Jun,Li, Zhongtao,Hu, Han,Wu, Mingbo
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- Acidic 1,3-propanediaminetetraacetato lanthanides with luminescent and catalytic ester hydrolysis properties
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In acidic solution, a serials of water-soluble coordination polymers (CPs) were isolated as zonal 1D-CPs 1,3-propanediaminetetraacetato lanthanides [Ln(1,3-H3pdta)(H2O)5]n· 2Cln·3nH2O [Ln=La, 1; Ce, 2; Pr, 3; Nd, 4; Sm, 5] (1,3-H4pdta=1,3-propanediaminetetraacetic acid, C11H 18N2O8) in high yields. When 1 eq. mol potassium hydroxide was added to the solutions of 1D-CPs, respectively, two 1D-CPs [Ln(1,3-H2pdta)(H2O)3] n·Cln·2nH2O [Ln=Sm, 6; Gd, 7] were isolated at room temperature and seven 2D-CPs [Ln(1,3-H2pdta) (H2O)2]n·Cln·2nH 2O [Ln=La, 8; Ce, 9; Pr, 10; Nd, 11; Sm, 12; Eu, 13; Gd, 14] were isolated at 70 °C. When the crystals of 1-4 were hydrothermally heated at 180 °C with 1-2 eq. mol potassium hydroxide, four 3D-CPs [Ln(1,3-Hpdta)]n·nH2O [Ln=La, 15; Ce, 16; Pr, 17; Nd, 18] were obtained. The two 2D-CPs [Ln(1,3-Hpdta)(H2O)] n·4nH2O (Sm, 19; Eu, 20) were isolated in similar reaction conditions. With the increments of pH value in the solution and reaction temperature, the structure becomes more complicated. 1-5 are soluble in water and 1 was traced by solution 13C{1H} NMR technique, the water-soluble lanthanides 1 and 5 show catalytic activity to ester hydrolysis reaction respectively, which indicate their important roles in the hydrolytic reaction. The europium complexes 13 and 20 show visible fluorescence at an excitation of 394 nm. The structure diversity is mainly caused by the variation of coordinated ligand in different pH values and lanthanide contraction effect. Acidic conditions are favorable for the isolations of lanthanide complexes in different structures and this may helpful to separate different lanthanides. The thermal stability investigations reveal that acidic condition is favorable to obtain the oxides at a lower temperature.
- Chen, Mao-Long,Shi, Yan-Ru,Yang, Yu-Chen,Zhou, Zhao-Hui
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- Kinetics of hydrogenation of acetic acid to ethanol
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The intrinsic kinetic behaviour of catalytic hydrogenation of acetic acid in vapour phase was studied over a multi-metallic catalyst. The rate expression was derived from the sequence of elementary reaction steps based on a Langmuir-Hinshelwood-model involving two types of active sites. Experiments were carried out in a fixed bed reactor, which is similar to an isothermal integral reactor designed to excluding the negative effects of internal and external diffusion. The reaction conditions investigated were as follow:reaction temperature 275-325 oC, reaction pressure1.5-3.0 MPa, liquid hourly space velocity (sv) 0.3-1.2 h-1, molar ratio of hydrogen to acetic acid (H/AC) 8:20. The results show that conversion of acetic acid increases with increasing the reaction temperature and pressure, but decreases with increasing the space velocity and H/AC. Furthermore, reducing the reaction pressure and increasing reaction temperature, space velocity and H/AC can improve the reaction selectivity of acetic acid to ethanol. The established kinetic model results agreed with experimental results. The relative difference between the calculated value and the experimental value is less than 6 %. The values of model parameters are consistent with the three thermodynamic constraints. The study provided evidence that the intrinsic kinetic model is suitable both mathematically and thermodynamically, and it could be useful in guiding reactor design and optimization of operating conditions.
- Chen, Qiang,Zhang, Xuebing,Tian, Shuxun,Long, Junying,Meng, Xiangkun,Sun, Qi,Li, Yonglong
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- Permanently polarized hydroxyapatite for selective electrothermal catalytic conversion of carbon dioxide into ethanol
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Conversion of CO2 into valuable chemicals is not only a very challenging topic but also a socially demanding issue. In this work, permanently polarized hydroxyapatite obtained using a thermal stimulated polarization process is proposed as a highly selective catalyst for green production of ethanol starting from CO2 and CH4.
- Sans, Jordi,Revilla-López, Guillem,Sanz, Vanesa,Puiggalí, Jordi,Turon, Pau,Alemán, Carlos
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- Effect of Mn doping on the activity and stability of Cu-SiO2 catalysts for the hydrogenation of methyl acetate to ethanol
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A series of xMn-Cu-SiO2 catalysts with different manganese contents were prepared by an ammonia-evaporation method for methyl acetate hydrogenation. The activity and stability of the catalysts were greatly improved when manganese content was 3%. Besides, physicochemical properties of these catalysts were investigated by N2 physisorption, X-ray diffraction, H2-temperature programmed reduction and X-ray photoelectron spectroscopy. The results illustrated that doping a suitable amount of manganese onto silica-supported copper catalysts produced a strong interaction between cupreous species and Mn, diminished the copper crystalline size, enlarged the copper surface area and enriched the surface Cu+ species, so as to improve the catalytic activity and stability of the 3Mn-Cu-SiO2 catalyst.
- Ye, Chenliang,Guo, Cuili,Sun, Chengwei,Zhang, Yu
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p. 113796 - 113802
(2016)
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- Porous Copper Microspheres for Selective Production of Multicarbon Fuels via CO2 Electroreduction
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The electroreduction of carbon dioxide (CO2) toward high-value fuels can reduce the carbon footprint and store intermittent renewable energy. The iodide-ion-assisted synthesis of porous copper (P-Cu) microspheres with a moderate coordination number of 7.7, which is beneficial for the selective electroreduction of CO2 into multicarbon (C2+) chemicals is reported. P-Cu delivers a C2+ Faradaic efficiency of 78 ± 1% at a potential of ?1.1 V versus a reversible hydrogen electrode, which is 32% higher than that of the compact Cu counterpart and approaches the record (79%) reported in the same cell configuration. In addition, P-Cu shows good stability without performance loss throughout a continuous operation of 10 h.
- Zou, Chengqin,Xi, Cong,Wu, Deyao,Mao, Jing,Liu, Min,Liu, Hui,Dong, Cunku,Du, Xi-Wen
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- Synthesis of Higher Alcohols via Syngas on Cu/Zn/Si Catalysts. Effect of Polyethylene Glycol Content
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Cu/Zn/Si catalysts with different polyethylene glycol (PEG) content were prepared by a complete liquid-phase method, and characterized by XRD, H2-TPR, N2-adsorption, and XPS. The influence of PEG content on the higher alcohols synthesis from syngas was investigated. The results showed that addition of PEG can influence the texture and surface properties of the catalysts, and therefore affect their activity and product distribution. With an increase in PEG content, BET surface area, Cu crystallite size and surface active ingredient content of the catalysts first increased and then decreased, the CO conversion had similar variation tendency. However, the pore volume and pore diameter of the catalyst increased, and the binding energy of the active component and the content of Cu2O decreased, which resulted in higher catalyst selectivity towards higher alcohols. The highest C2+OH selectivity in total alcohols was 60.6 wt %.
- Cui, Rong-Ji,Yan, Xing,Fan, Jin-Chuan,Huang, Wei
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- Encapsulation of Two Potassium Cations in Preyssler-Type Phosphotungstates: Preparation, Structural Characterization, Thermal Stability, Activity as an Acid Catalyst, and HAADF-STEM Images
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Dipotassium cation (K+)-encapsulated Preyssler-type phosphotungstate, [P5W30O110K2]13-, was prepared by heating monobismuth (Bi3+)-encapsulated Preyssler-type phosphotungstate, [P5W30O110Bi(H2O)]12-, in acetate buffer in the presence of an excess amount of potassium cations. Characterization of the isolated potassium salt, K13[P5W30O110K2] (1a), and its acid form, H13[P5W30O110K2] (1b), by single crystal X-ray structure analysis, 31P and 183W nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammetry (CV), high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS), and elemental analysis revealed that two potassium cations are encapsulated in the Preyssler-type phosphotungstate molecule with formal D5h symmetry, which is the first example of a Preyssler-type compound with two encapsulated cations. Incorporation of two potassium cations enhances the thermal stability of the potassium salt, and the acid form shows catalytic activity for hydration of ethyl acetate. Packing of the Preyssler-type molecules was observed by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).
- Hayashi, Akio,Ota, Hiromi,López, Xavier,Hiyoshi, Norihito,Tsunoji, Nao,Sano, Tsuneji,Sadakane, Masahiro
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- Homogeneously Catalysed Disproportionation of Acetaldehyde into Ethanol and Acetic Acid
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The complexes + (1), , M = Rh or Ir, , and + all catalyse the disproportionation of acetaldehyde to acetic acid and ethanol in water in the absence of base, and other aldehydes react similarly; rhodium hydride complexes can be isolated from the reactions involving (1).
- Cook, John,Hamlin, John E.,Nutton, Andrew,Maitlis, Peter M.
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- Highly active Ce, Y, La-modified Cu/SiO2 catalysts for hydrogenation of methyl acetate to ethanol
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Rare earth element (Ce, Y, and La) modified Cu/SiO2 catalysts via hydrolysis precipitation and impregnation method were fabricated for the vapor-phase hydrogenation of methyl acetate to ethanol. LaOx showed the most pronounced promotion in the catalytic tests. After detailed characterizations, via N2 adsorption-desorption, XRD, N2O chemisorption, FTIR, H2-TPR, H2-TPD, TEM, XPS, and TG/DTA, we found that the addition of promoter LaOx can decrease the particle size while in turn, it can increase the dispersion of copper species. The strong interactions between copper and lanthanum atoms alter the surface chemical states of the copper species. This results in the generation of more Cu+ species and high SCu+ values, which are responsible for the excellent activity and stability during hydrogenation. In addition, the content of additive LaOx and reaction conditions (reaction temperature and LHSV) were optimized. Then, the long-term stability performance was evaluated over the selected catalyst in contrast with Cu/SiO2.
- Li, Chunshan,Li, Zengxi,Ren, Zhiheng,Wang, Gongying,Yang, Xiangui,Younis, Muhammad Naeem
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- Hydrolysis of S-2-aminoethylcysteinyl peptide bond by Achromobacter protease I.
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The substrate specificity of Achromobacter protease I (API) was examined for S-2-aminoethyl(AE)cysteinyl bonds in Bz-AEC-OMe/OEt, Bz-AEC-NH2, and AE-insulin B chain. The protease hydrolyzed all of the tested AE-cysteinyl bonds at the same rate as that of lysyl bonds. Kinetic parameters were estimated for this hydrolysis reaction.
- Masaki,Takiya,Tsunasawa,Kuwahara,Sakiyama,Soejima
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- Designing a novel dual bed reactor to realize efficient ethanol synthesis from dimethyl ether and syngas
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A novel dual bed reactor packed with a combination of a zeolite (H-modernite or H-ferrierite) catalyst and a CuZnAl catalyst was proposed to realize direct ethanol (EtOH) synthesis from dimethyl ether (DME) and syngas (CO + H2). DME and CO were firstly introduced into the upper zeolite bed to commence the carbonylation reaction, and then H2 was directly introduced into the CuZnAl catalyst bed below to accomplish the hydrogenation of methyl acetate (MA) produced at the first catalyst bed. In this novel dual bed process, DME and CO were introduced into the reactor at the top of the first catalyst bed layer, but H2 was introduced into the second catalyst bed layer directly through an inner stainless steel tube equipped with evenly distributed holes. Benefitting from the precise control of the distribution of the reactants on the surface of different catalysts, an enhanced catalytic performance was obtained compared with the conventional dual bed reactor which introduced DME and syngas into the reactor simultaneously. The synergistic effects offered by this novel dual bed reactor were further confirmed by numerous comparative tests. Our results show that the excellent catalytic performance in this novel dual bed reactor was ascribed to the improved CO partial pressure in the upper zeolite catalyst bed. Compared with the conventional dual bed reactor, both DME conversion and EtOH yield were almost doubled in this novel dual bed reactor packed with the combination of the H-ferrierite and CuZnAl catalysts.
- Gao, Xinhua,Xu, Bolian,Yang, Guohui,Feng, Xiaobo,Yoneyama, Yoshiharu,Taka, Ushio,Tsubaki, Noritatsu
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- CO2 Hydrogenation to Ethanol over Cu@Na-Beta
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Here, we report a high-performance catalyst Cu@Na-Beta, prepared via a unique method to embed 2～5 nm Cu nanoparticles in crystalline particles of Na-Beta zeolite, for CO2 hydrogenation to ethanol as the only organic product in a traditional fixed-bed reactor. The ethanol yield in a single pass can reach ～14% at 300°C, ～12,000 mL·gcat?1·h?1, and 2.1 MPa, corresponding to a space-time yield of ～398 mg·gcat?1·h?1. The key step of the reaction is considered as the rapid bonding of CO2? with surface methyl species at step sites of Cu nanoparticles to CH3COO? that converts to ethanol in following hydrogenation steps. The points of the catalyst seemed to be that the irregular copper nanoparticles stuck in zeolitic frameworks offer high density of step sites and the intimate surrounding of zeolitic frameworks strongly constrain the CO2 reactions at the copper surface and block by-products, such as methanol, formic acid, and acetyl acid. The high-performance catalyst Cu@Na-Beta, prepared via a unique method to embed 2～5 nm Cu nanoparticles in crystalline particles of Na-Beta zeolite, is reported for CO2 hydrogenation to ethanol as the only organic product in a traditional fixed-bed reactor. The ethanol yield in a single pass can reach ～14% at 300°C, ～12,000 mL·gcat?1·h?1, and 2.1 MPa, corresponding to space-time yield of ～398 mg·gcat?1·h?1. The key step of the reaction is the rapid bonding of CO2? with surface methyl species at step sites of Cu nanoparticles to CH3COO?, which converts to ethanol in the following hydrogenation steps. The points of the catalyst seem to be that the irregular copper nanoparticles stuck in zeolitic frameworks offer a high density of step sites and that the intimate surrounding of zeolitic frameworks strongly constrains the CO2 reactions at the copper surface and blocks byproducts such as methanol, formic acid, and acetyl acid. CO2 direct reduction to ethanol is a much-anticipated research topic worldwide. A big progress has been made in the current investigation toward industry application. A high-performance catalyst Cu@Na-Beta, prepared via a unique method to embed 2～5 nm Cu nanoparticles in crystalline particles of Na-Beta zeolite, is reported for CO2 hydrogenation to ethanol in a traditional fixed-bed reactor, with ethanol space-time yield of ～398 mg·gcat?1·h?1. Peripherals-surrounded catalysts, which may be called mesocatalysts, appear to be one focus of future investigations on catalysis.
- Ding, Liping,Shi, Taotao,Gu, Jing,Cui, Yun,Zhang, Zhiyang,Yang, Changju,Chen, Teng,Lin, Ming,Wang, Peng,Xue, Nianhua,Peng, Luming,Guo, Xuefeng,Zhu, Yan,Chen, Zhaoxu,Ding, Weiping
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- Active sites in CO2 hydrogenation over confined VOx-Rh catalysts
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Metal oxide-promoted Rh-based catalysts have been widely used for CO2 hydrogenation, especially for the ethanol synthesis. However, this reaction usually suffers low CO2 conversion and alcohols selectivity due to the formation of byp
- Wang, Guishuo,Luo, Ran,Yang, Chengsheng,Song, Jimin,Xiong, Chuanye,Tian, Hao,Zhao, Zhi-Jian,Mu, Rentao,Gong, Jinlong
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- Acetic acid hydroconversion to ethanol over novel InNi/Al2O 3 catalysts
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Consecutive reduction of acetic acid (AA) to ethanol was studied looking for an advantageous catalyst for the processing of VFAs (volatile fatty acids) that can be produced by thermochemical or biological biomass degradation. A fixed bed flow-through reactor was applied with hydrogen stream at 21 bar total pressure in the temperature range of 220-380°C. AA hydroconversion activity of the parent alumina supported Ni catalyst and the yield of selectively produced alcohol can be increased drastically by In2O3 addition. Efficient catalysts, containing finely dispersed metal particles were obtained by reduction with H2 at 450°C. In the catalysts modified with In2O3 additive formation of indium metal and/or an intermetallic compound (InNi2) was observed resulting in a different catalytic behavior as for pure nickel particles supported on alumina. Appearance of metallic indium can direct the step by step catalytic reduction to ethanol formation inhibiting decarbonylation, decarboxylation, and additional dehydration. On comparing the commercial, conventionally used catalysts with the bimetallic alumina supported composite (InNi/Al2O3) the novel catalyst proved to be much more active and selective for producing ethanol.
- Onyestyák, Gy?rgy,Harnos, Szabolcs,Kaszonyi, Alexander,?tolcová, Magdalena,Kalló, Dénes
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- Effect of Preparation Method on the Structure and Catalytic Performance of CuZnO Catalyst for Low Temperature Syngas Hydrogenation in Liquid Phase
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Abstract: CuZnO catalysts were prepared by different methods, characterized by applying a combination of techniques, and the effect of preparation method on the structure and the catalytic performance for syngas hydrogenation at low temperature in liquid phase was investigated. The results showed that due to the difference of the interaction between Cu and Zn, the preparation method greatly affected the crystallinity of CuZnO. The crystallinity of CuZnO had a direct relation with the CO adsorption property. The total CO adsorption amount determined the catalytic activity, the weak adsorption of CO accounted for the methanol synthesis, while the strong adsorption of CO accounted for the ethanol synthesis. CuZnO prepared by the homogeneous precipitation with the lowest crystallinity exhibited the highest total carbon conversion of 68.6% with the methanol selectivity of 84.9%, while CuZnO prepared by the sol gel with the highest crystallinity exhibited the highest ethanol selectivity of 47.6%. Graphical Abstract: The preparation method of CuZnO had a significant effect on the CO adsorption property and then resulted in a substantial modification in the product distribution for the syngas hydrogenation at low temperature in liquid phase. The catalytic activity was determined by the total amount of CO adsorption, the weak CO adsorption accounted for the methanol synthesis and the strong CO adsorption accounted for the ethanol synthesis. [Figure not available: see fulltext.]
- Liu, Huan,Chen, Tong,Wang, Gongying
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- Reduction of Potassium Acetate and Potassium Propionate With Lithium Aluminium Hydride in the Presence of Phase-Transfer Catalysts
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Ethyl alcohol and propyl alcohol can be prepared with good yields from potassium carboxylates by the reduction with lithium aluminium hydride in the presence of different phase transfer catalysts. - Keywords: Crown ethers; Phase-transfer catalysts; Reduction
- Szakacs, Sandor,Goeboeloes, Sandor,Szammer, Janos
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- Insight into the role of hydroxyl groups on the ZnCr catalyst for isobutanol synthesis from syngas
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A series of ZnO, ZnCr catalysts were prepared by a sol-gel method and ammonia solution was used to adjust the pH of the sol solution. The catalysts were characterized by XRD, in-situ FR-IR, NH3-TPD, in-situ XPS, HRTEM. The results show that lower calcination temperature is helpful to reduce the crystal size and crystallinity of ZnCr nanocrystal, as well as forming a certain amount of structure defects and hydroxyl groups. The hydroxyl groups could be consumed by CO under the interaction between ZnO and ZnCr spinel, resulting in more exposed oxygen vacancies. We find the proper calcination temperature and Zn/Cr molar ratio for the ZnCr catalysts preparation are 400 °C and 1.0, respectively. The Zn1Cr1–400 ～ 2.0 catalyst prepared with the pH value of 2 shows more hydroxyl groups and small particle size, exhibiting the best catalytic performance both on the CO conversion (20.9%) and isobutanol selectivity (24.2 wt%).
- Gao, Xiaofeng,Wu, Yingquan,Yang, Guohui,Zhang, Tao,Li, Xiaoli,Xie, Hongjuan,Pan, Junxuan,Tan, Yisheng
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- Effect of the ZnO/SiO2ratio on the structure and catalytic activity of Cu/SiO2and Cu/ZnO catalysts in water-containing ester hydrogenation
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The effects of the ZnO/SiO2 ratio on the water tolerance of Cu/SiO2 and Cu/ZnO catalysts were studied by ethyl acetate with 5 wt% water hydrogenation. Notably, the addition of an appropriate amount of ZnO endows Cu/SiO2 catalysts with satisfactory water-tolerant hydrogenation performance by a decrease in the reaction temperature without sacrificing conversion. At the same time, agglomeration can be alleviated for Cu/ZnO catalysts due to the optimal addition of SiO2, which is considered as a partition material that effectively hinders the agglomeration of the Cu/ZnO catalyst. However, the addition of ZnO was not favourable for the copper dispersion of Cu/SiO2. The stability of Cu/SiO2 catalyst quickly degraded due to excessive ZnO being introduced by sintering. The copper dispersion of Cu/ZnO catalysts initially increased with increasing SiO2 content, but then decreased. The addition of excess SiO2 also led to decreased activity and rapid deactivation of the Cu/ZnO catalyst. In our study, the appropriate addition of ZnO (5 wt%) and SiO2 (5 wt%) had a positive effect on the Cu/SiO2 and Cu/ZnO catalysts, respectively.
- Chen, Zheng,Wei, Shuwei,Zhao, Xueying,Wang, Dengfeng,Chen, Jiangang
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- Photolysis of Zeise salt in aqueous solution: Photocatalysis of the hydration of olefins to alcohols
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The photolysis of aqueous Zeise salt essentially leads to the release of ethylene, but about 10% undergo a photohydration which is initiated by MLCT excitation:PtIICl3(C2H4)] - + 2 H2O - hν→ [PtII(H 2O)Cl3] - + CH3CH2OH Since [Pt(H2O)Cl3]- adds again ethylene to regenerate [Pt(C2H4)Cl3]- the overall reaction proceeds as a photocatalysis converting C2H 4 to C2H5OH. When ethylene was replaced by 1-hexene the photoaquation to 1-hexanol takes place with TON > 2.30.
- Kunkely, Horst,Vogler, Arnd
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- Near-infrared kinetic spectroscopy of the HO2and C 2H5O2 self-reactions and cross reactions
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The self-reactions and cross reactions of the peroxy radicals C 2H5O2 and HO2 were monitored using simultaneous independent; spectroscopic probes to observe each radical species. Wavelength modulation (WM) near-infrared (NIR) spectroscopy was used to detect HO 2, and UV absorption monitored C2H2O 2. The temperature dependences of these reactions were investigated over a range of interest; to tropospheric chemistry, 221-296 K. The Arrhenius expression determined for the cross reaction, k2(T) = (6.01 +1.95 -1.47) x 10-13 exp((638 ± 73)/T) cm3 molecules-1 s-1 is in agreement with other work from the literature. The measurements of the HO2 self-reaction agreed with previous work from, this lab and were not further refined. The C2H5O2 self-reaction is complicated by secondary production of HO2. This experiment performed the first direct measurement of the self-reaction rate constant, as well as the branching fraction to the radical channel, in part; by measurement of the secondary HO2. The Arrhenius expression for the self-reaction rate constant is k3(T) = (1.29 +0.34 -0.27) x 10-13 exp((-23 ± 61)/T) cm3 molecules-1 s- and the branching fraction value is α = 0.28 ± 0.06, independent of temperature. These values are in disagreement with previous measurements based on end product studies of the blanching fraction. The results suggest that better characterization of the products from RO2 self-reactions are required.
- Noell,Alconcel,Robichaud,Okumura,Sander
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- Low-temperature methanol synthesis catalyzed over Pd/CeO2
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Methanol is effectively synthesized from carbon monoxide and hydrogen at a reaction temperature as low as 170 °C over Pd/CeO2 in which the palladium species are cationic after reduction with hydrogen at 300 °C.
- Matsumura, Yasuyuki,Shen, Wen-Jie,Ichihashi, Yuichi,Okumura, Mitsutaka
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- Photoinduction of Cu single atoms decorated on UiO-66-NH2for enhanced photocatalytic reduction of CO2to liquid fuels
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Photocatalytic reduction of CO2 to value-added fuels is a promising route to reduce global warming and enhance energy supply. However, poor selectivity and low efficiency of catalysts are usually the limiting factor of their applicability. Herein, a photoinduction method was developed to achieve the formation of Cu single atoms on a UiO-66-NH2 support (Cu SAs/UiO-66-NH2) that could significantly boost the photoreduction of CO2 to liquid fuels. Notably, the developed Cu SAs/UiO-66-NH2 achieved the solar-driven conversion of CO2 to methanol and ethanol with an evolution rate of 5.33 and 4.22 μmol h-1 g-1, respectively. These yields were much higher than those of pristine UiO-66-NH2 and Cu nanoparticles/UiO-66-NH2 composites. Theoretical calculations revealed that the introduction of the Cu SAs on the UiO-66-NH2 greatly facilitates the conversion of CO2 to CHO? and CO? intermediates, leading to excellent selectivity toward methanol and ethanol. This study provides new insights for designing high-performance catalyst for photocatalytic reduction of CO2 at the atomic scale.
- Wang, Gang,He, Chun-Ting,Huang, Rong,Mao, Junjie,Wang, Dingsheng,Li, Yadong
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- Electrochemical reduction of formic acid through its decarbonylation in phosphoric acid solution
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The electrochemical reduction of formic acid on a copper cathode in 85% w/w H3PO4 electrolyte at 70 °C was studied. In this electrolyte formic acid is partially decomposed to carbon monoxide and water. The experimental results showed that the formation of the products is strongly related to the presence of carbon monoxide in the solution and this suggests that CO is the key intermediate for the formation of the detected producs. At -0.45 V vs. Ag/AgCl the main products were CH3OH and CH3CHO with %Current Efficiency (%CE) of 27.6 and 25.8% respectively, whereas a part of the produced methanol(about 50%) was converted to methyl dihydrogen phosphate (25%) and methyl formate (21.8%). At more negative potentials than -0.5 V ethanol was produced by a maximum %CE of 7.9% at -0.75 V. The electrochemical reduction of a CO saturated solution under the same conditions gave the same products albeit the %CE of methanol was lower.
- Schizodimou,Kotoulas,Kyriacou
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- Cu9-Alx-Mgy catalysts for hydrogenation of ethyl acetate to ethanol
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Cu9-Alx or Cu9-Alx-My (M?=?Mg, Ca, Ba or Sr) catalysts were prepared by a deposition-precipitation method, characterized by means of H2-TPR, XRD and N2 sorption, and applied for hydrogenation of ethyl acetate to ethanol in a fixed-bed reactor. The molar ratio of Cu/Al or Cu/Al/M and the reaction parameters were investigated thoroughly. As a result, the Cu9-Al0.5-Mg1.5 catalyst with higher specific surface area, lower initial reduction temperature and better metal dispersion furnished 97.8% ethyl acetate conversion with 98% selectivity to ethanol under optimal reaction conditions. Moreover, the Cu9-Al0.5-Mg1.5 catalyst also showed good lifetime and neither the activity nor selectivity decreased during 210?h test. Based on the characterization of the Cu9-Al0.5-Mg1.5 catalyst, the optimal Cu+/Cu0 proportion played a key role in determining the superior performance.
- Tian, Jingxia,Hu, Jun,Shan, Wenjuan,Wu, Peng,Li, Xiaohong
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- Electroreduction of CO2 on Single-Site Copper-Nitrogen-Doped Carbon Material: Selective Formation of Ethanol and Reversible Restructuration of the Metal Sites
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It is generally believed that CO2 electroreduction to multi-carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of copper atoms. Here, we report on an inexpensive Cu-N-C material prepared via a simple pyrolytic route that exclusively feature single copper atoms with a CuN4 coordination environment, atomically dispersed in a nitrogen-doped conductive carbon matrix. This material achieves aqueous CO2 electroreduction to ethanol at a Faradaic yield of 55 % under optimized conditions (electrolyte: 0.1 m CsHCO3, potential: ?1.2 V vs. RHE and gas-phase recycling set up), as well as CO electroreduction to C2-products (ethanol and ethylene) with a Faradaic yield of 80 %. During electrolysis the isolated sites transiently convert into metallic copper nanoparticles, as shown by operando XAS analysis, which are likely to be the catalytically active species. Remarkably, this process is reversible and the initial material is recovered intact after electrolysis.
- Karapinar, Dilan,Huan, Ngoc Tran,Ranjbar Sahraie, Nastaran,Li, Jingkun,Wakerley, David,Touati, Nadia,Zanna, Sandrine,Taverna, Dario,Galv?o Tizei, Luiz Henrique,Zitolo, Andrea,Jaouen, Frédéric,Mougel, Victor,Fontecave, Marc
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- Insight into the Correlation between Cu Species Evolution and Ethanol Selectivity in the Direct Ethanol Synthesis from CO Hydrogenation
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Cu/SiO2 catalyst was prepared by the ammonia evaporation method for the direct synthesis of ethanol from CO hydrogenation. The catalyst exhibited the initial ethanol selectivity as high as 40.0 wt %, which dramatically decreased from 40.0 to 9.6 wt % on the stream of 50 h. XRD, XPS, TEM and N2O titration techniques were employed to elucidate the ethanol selectivity change and catalyst structure evolution during reaction process. The experiment and characterization results indicated that both Cu+/(Cu++Cu0) value and copper crystallite size had great effects on the ethanol selectivity. During the initial 38 h, the ethanol selectivity obviously decreased from 40.0 to 18.2 wt %, and Cu+/(Cu++Cu0) value on the catalyst surface rapidly dropped from 0.67 to 0.39, while the copper crystallite size remained almost unchanged. However, during the reaction period of 38–50 h, the Cu+/(Cu++Cu0) value possessed no distinct change, but a further decrease in ethanol selectivity and a rapid aggregation in Cu particles were observed simultaneously. The present systematic investigation demonstrated that the decrease of Cu+/(Cu++Cu0) value was the main factor for the loss of ethanol selectivity during the initial 38 h, whereas the rapid growth of Cu particles during the reaction period of 38–50 h were mainly contributed to the further decline of ethanol selectivity.
- Li, Xiao-Li,Yang, Guo-Hui,Zhang, Meng,Gao, Xiao-Feng,Xie, Hong-Juan,Bai, Yun-Xing,Wu, Ying-Quan,Pan, Jun-Xuan,Tan, Yi-Sheng
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- Single-pulse shock tube study of the decomposition of tetraethoxysilane and related compounds
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Tetraethoxysilane (TEOS) has been decomposed in single-pulse shock tube experiments over the temperature range 1160-1285 K and pressures of about 150 kPa (1.5 bar). The main observed products are ethylene and ethanol. The yields of these products as a percentage of decomposed TEOS increase with temperature. Studies have also been carried out with tetra-n-propoxysilane (TPOS), dimethyldiethoxysilane (DMDEOS), and trimethylethoxysilane (TMEOS). Evidence is presented that in all cases the main initial reaction is a 1,2-elimination to form the olefin and the corresponding silanol. A smaller contribution from C-C bond-breaking channels is also observed. In combination with lower temperature results and the thermochemistry, the following rate expressions for the elementary processes are recommended: k[TEOS→C2H4+HOSi(OC2H5)3] = 1.04×1010T1.1 exp(-30 950 K/T) s-1; k[TEOS→CH3+CH2OSi(OC2H5)3] = 4×1017 exp(-43 300 K/T) s-1. The observed ethanol product is postulated to arise from decomposition of the silanol in a gas phase reaction. A kinetic model which quantitatively accounts for the observed products in the decomposition of TEOS, DMDEOS, and TMEOS has been developed. The model includes radical reactions as well as molecular reactions of the silanol and subsequently formed products, including silicates and silyl acids. The model requires an activation energy of ≤200 kJ mol-1 for the reaction which forms ethanol from the silanol. Such a low barrier is apparently at odds with recently calculated values for the thermochemistry of some silicon compounds.
- Herzler,Manion,Tsang
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- Synthesis, characterization, thermogravimetry, and structural study of uranium complexes derived from dibasic S-alkylated thiosemicarbazone ligands
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Two pentagonal bipyramidal complexes, ethanol-(S-ethyl-N1,N 4-bis(3-methoxy-2-hydroxybenzaldehyde)-isothiosemicarbazide-N,N',O, O')-dioxidouranium(VI) (1) and ethanol-(S-ethyl-N1-(2- hydroxyacetophenone)-N4-(5-bromo-2-hydroxybenzaldehyde)- isothiosemicarbazide-N,N',O,O')-dioxidouranium(VI) (2), have been prepared and characterized. Their structures have been determined by X-ray crystallography, and the structural parameters are discussed with those observed in related complexes. Electronic absorption, proton magnetic resonance, and FT-IR spectra have been recorded and analyzed. In both complexes, the U(VI) centers are surrounded by N2O2 donor ligands, two oxido groups, and one ethanol in a distorted pentagonal bipyramid. The thermal stability of the new complexes has also been determined. 2014
- Fasihizad, Ahad,Barak, Tahere,Ahmadi, Mehdi,Dusek, Michal,Pojarova, Michaela
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- Spectroscopic evidence for origins of size and support effects on selectivity of Cu nanoparticle dehydrogenation catalysts
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Selective dehydrogenation catalysts that produce acetaldehyde from bio-derived ethanol can increase the efficiency of subsequent processes such as C-C coupling over metal oxides to produce 1-butanol or 1,3-butadiene or oxidation to acetic acid. Here, we use in situ X-ray absorption spectroscopy and steady state kinetics experiments to identify Cuδ+ at the perimeter of supported Cu clusters as the active site for esterification and Cu0 surface sites as sites for dehydrogenation. Correlation of dehydrogenation and esterification selectivities to in situ measures of Cu oxidation states show that this relationship holds for Cu clusters over a wide-range of diameters (2-35 nm) and catalyst supports and reveals that dehydrogenation selectivities may be controlled by manipulating either.
- Witzke,Dietrich,Ibrahim,Al-Bardan,Triezenberg,Flaherty
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- Sensitization of la modified NaTaO3 with cobalt tetra phenyl porphyrin for photo catalytic reduction of CO2 by water with UV-visible light
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Lanthanum modified sodium tantalate, Na(1-x)LaxTaO(3+x), in conjunction with cobalt (II) tetra phenyl porphyrin (CoTPP) as sensitizer, has been explored for photo catalytic reduction of carbon dioxide (PCRC) with water. HOMO and LUMO energy level characteristics/redox potentials for ground (S0) and excited states (S1 singlet) of CoTPP have been calculated by Density Functional Theory (DFT). HOMO and LUMO energy levels enable sensitization of the tantalate, a typical wide band gap semi-conductor, with visible light. Visible light absorption by CoTPP results in the direct transfer of photo generated electrons to the conduction band of the tantalate, in addition to the intrinsic UV light excitation. Besides, sensitization also retards charge carrier recombination rate, as indicated by the photo luminescence spectral data for the pristine and sensitized Na(1-x)LaxTaO(3+x). A co-operative effect of these factors contributes towards nearly 3 fold increase in apparent quantum yield value for PCRC with the 1% w/w CoTPP/tantalate composite vis-à-vis pristine tantalate. After 20 h of irradiation, rate of methanol formation remains constant with pristine and sensitized tantalates, while the rate of formation of ethanol increases on sensitization, indicating multi electron reduction process. Chemical composition and structural characteristics of the composite are preserved even after 20 h of irradiation.
- Jeyalakshmi, Velu,Tamilmani, Selvaraj,Mahalakshmy, Rajaram,Bhyrappa, Puttaiah,Krishnamurthy, Konda Ramasamy,Viswanathan, Balasubramanian
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- Efficient methane electrocatalytic conversion over a Ni-based hollow fiber electrode
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Natural gas and shale gas, with methane as the main component, are important and clean fossil energy resources. Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis. Substantial studies on processes including methane reforming, oxidative coupling of methane, non-oxidative coupling of methane, etc. have been conducted for many years. However, owing to the intrinsic chemical inertness of CH4, harsh reaction conditions involving either extremely high temperatures or highly oxidative reactants are required to activate the C–H bonds of CH4 in such thermocatalytic processes, which may cause the target products, such as ethylene or methanol, to be further converted into coke or CO and CO2. It is desirable to adopt a new strategy for direct CH4 conversion under mild conditions. Herein, we report that efficient electrocatalytic oxidation of methane to alcohols at ambient temperature and pressure can be achieved using a NiO/Ni hollow fiber electrode. This work opens a new avenue for direct catalytic conversion of CH4.
- Chen, Wei,Dong, Xiao,Guo, Zhikai,Li, Guihua,Song, Yanfang,Sun, Yuhan,Wei, Wei
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- Facile Synthesis of Cu@CeO2 and Its Catalytic Behavior for the Hydrogenation of Methyl Acetate to Ethanol
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The hydrogenation of methyl acetate (MA) is one of the key steps in the synthesis of ethanol from syngas. Given previous studies in this area, synergy of the Cu0 and Cu+ species is the crux to improving catalytic performance. However, neither Cu0 nor Cu+ is easy to maintain under reaction conditions comprising abundant H2 and high temperature. Here, a Cu@CeO2 core–shell catalyst was fabricated by using a facile sol–gel method, and this catalyst exhibited excellent activity and stability in the hydrogenation of MA. It was revealed that the Cu@CeO2 core–shell structure prevented the metallic copper particles from migrating and aggregating and also significantly increased the amount of Cu+ species by enlarging the intimate contact area of copper and ceria. Furthermore, the Cu0 and Cu+ species were found to be well distributed on the interface between the Cu core and the CeO2 shell. The close relative position of the two active sites is probably the main reason for the enhanced synergetic effect in the hydrogenation of MA. New insight into the core–shell structure–function relationship introduces new possibilities for the rational design of catalysts.
- Wang, Yue,Zhao, Yujun,Lv, Jing,Ma, Xinbin
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- Hydrogenation of carbon dioxide to methanol by using a homogeneous ruthenium-phosphine catalyst
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Simply efficient: The homogenously catalyzed hydrogenation of CO 2 to methanol is achieved by using a ruthenium phosphine complex under relatively mild conditions (see scheme; HNTf2= bis(trifluoromethane)sulfonimide). This is the first example of CO2 hydrogenation to methanol by using a single molecularly defined catalyst. Copyright
- Wesselbaum, Sebastian,Vom Stein, Thorsten,Klankermayer, Juergen,Leitner, Walter
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- Nitric oxide as an activation agent for nucleophilic attack in trans-[Ru(NO)(NH3)4{P(OEt)3}](PF 6)3
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The complex trans-[Ru(NO)(NH3)4{P(OEt) 3}](PF6)3 undergoes nucleophilic attack on the phosphorus ester ligand in the solid state yielding trans-[Ru(NO)(NH 3)4{P(OH)(OEt)2/s
- Metzker, Gustavo,Toledo Jr., Jose? C.,Lima, Francisco C. A.,Magalha?es, Alvicler,Cardoso, Daniel R.,Franco, Douglas W.
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- Preparation of a Cu(BTC)-rGO catalyst loaded on a Pt deposited Cu foam cathode to reduce CO2 in a photoelectrochemical cell
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To increase the reaction productivity and selectivity of the CO2 photoelectrochemical reduction reaction, a Cu (benzene 1,3,5-tricarboxylic acid [BTC])-reduced graphite oxide (rGO) catalyst was prepared by using a facile hydrothermal method and used in a CO2 photoelectrochemical cell (PEC) as a cathode catalyst. Characterization of the catalyst proved that successfully bonding of rGO to Cu(BTC) not only facilitated faster transfer of electrons on the surface of the catalyst but also created more active sites. CO2 photoelectrochemical reduction experimental results showed that the total carbon atom conversion rate was up to 3256 nmol h-1 cm-2 which was much higher than when pure Cu(BTC) was used as a cathode catalyst. The liquid product's selectivity to alcohols was up to 95% when-2 V voltage was applied to the system with Cu(BTC)-rGO used as the cathode catalyst.
- Cheng, Jun,Xuan, Xiaoxu,Yang, Xiao,Zhou, Junhu,Cen, Kefa
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- 2-(4-Nitrophenyl)-1H-indolyl-3-methyl Chromophore: A Versatile Photocage that Responds to Visible-light One-photon and Near-infrared-light Two-photon Excitations
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Due to cell damage caused by UV light, photoremovable protecting groups (PPGs) that are removed using visible or near-infrared light are attracting attention. A 2-(4-nitrophenyl)- 1H-indolyl-3-methyl chromophore (NPIM) was synthesized as a novel PPG. Various compounds were caged using this PPG and uncaged using visible or near-infrared light. Low cytotoxicity of NPIM indicates that it may be applied in physiological studies.
- Abe, Manabu,Guo, Runzhao,Hamao, Kozue,Lin, Qianghua,Takagi, Ryukichi
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supporting information
p. 153 - 156
(2022/02/14)
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- Stable ethanol synthesis via dimethyl oxalate hydrogenation over the bifunctional rhenium-copper nanostructures: Influence of support
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Addition of oxophilc rhenium to decorate small copper nanoparticles has been validated to be an efficient method to prepare a low-copper catalyst for the direct synthesis of ethanol via dimethyl oxalate (DMO) hydrogenation process, and herein we investigated the impact of supports on the catalytic performance of ReCu catalysts. A series of materials including activated carbon (AC), Al2O3, SiO2, TiO2 and ZrO2 were utilized as the support and as prepared Re2Cu5 catalysts were evaluated. The results exhibited that the Re2Cu5/ZrO2 catalyst possesses the highest DMO hydrogenation activity and ethanol yield (～93%), which may be due to its lowest Cu0/Cu+ ratio (0.13), smallest Cu particle size (～0.84 nm) a relative high reduction degree (59%). The CO adsorption behavior characterized by in situ IR spectroscopy showed that a strong metal-support interaction creates an electron deficient environment of Cu nanoparticle, resulting in a lower Cu0/Cu+ ratio that enhances the activation of C[dbnd]O bond in the DMO molecular.
- Chen, Xingkun,Ding, Yunjie,Du, Zhongnan,Li, Zheng,Lin, Ronghe,Wang, Shiyi,Wang, Xuepeng,Zhu, Hejun
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p. 241 - 252
(2022/02/22)
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- Nanoconfinement Engineering over Hollow Multi-Shell Structured Copper towards Efficient Electrocatalytical C?C coupling
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Nanoconfinement provides a promising solution to promote electrocatalytic C?C coupling, by dramatically altering the diffusion kinetics to ensure a high local concentration of C1 intermediates for carbon dimerization. Herein, under the guidance of finite-element method simulations results, a series of Cu2O hollow multi-shell structures (HoMSs) with tunable shell numbers were synthesized via Ostwald ripening. When applied in CO2 electroreduction (CO2RR), the in situ formed Cu HoMSs showed a positive correlation between shell numbers and selectivity for C2+ products, reaching a maximum C2+ Faradaic efficiency of 77.0±0.3 % at a conversion rate of 513.7±0.7 mA cm?2 in a neutral electrolyte. Mechanistic studies clarified the confinement effect of HoMSs that superposition of Cu shells leads to a higher coverage of localized CO adsorbate inside the cavity for enhanced dimerization. This work provides valuable insights for the delicate design of efficient C?C coupling catalysts.
- Li, Jiawei,Liu, Chunxiao,Xia, Chuan,Xue, Weiqing,Zeng, Jie,Zhang, Menglu,Zheng, Tingting
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supporting information
(2021/12/06)
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- Selectively chemo-catalytic hydrogenolysis of cellulose to EG and EtOH over porous SiO2 supported tungsten catalysts
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Cellulosic ethanol produced from lignocellulose biomass can alleviate the shortage of conventional fossil energy supply and reduce global CO2 emissions. Wherein, hydrogenolysis of cellulose to ethanol is a new method for the synthesis of fuel ethanol, which could theoretically utilizes all carbon atoms in glucose in the direct retro-aldol condensation (RAC) reaction to produce ethanol, and can potentially break through the technical bottleneck of biological methods. Herein, we show that the benefits of the mesoporous structure of tungsten-based catalysts can be leveraged to influence the selective hydrogenolysis of cellulose into C2 products. Comparing the performance of different pore size SiO2 supported tungsten catalysts and detailed characterizations revealed that the mesoporous structure of supports can affect the morphology, crystal sizes, and surface chemistry of the catalysts, which presented a combined effect on the hydrogenolysis reaction. Whereby, 51.5 wt% ethylene glycol (EG) was obtained from the direct hydrogenolysis of cellulose over Ru-WOx/SiO2 (500 ?) catalyst under 513 K, and 40.5 wt% ethanol (EtOH) was obtained from the direct hydrogenolysis of cellulose over Ir-WOx/SiO2 (500 ?) catalyst under 553 K, respectively.
- Fan, Maohong,Mu, Shifang,Sun, Qi,Wang, Haiyong,Wang, Xiaolong,Wang, Yan,Weng, Yujing,Zhang, Mingwei,Zhang, Yulong
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- (Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
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The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
- Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
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supporting information
p. 1609 - 1615
(2021/03/09)
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- Converging conversion - using promiscuous biocatalysts for the cell-free synthesis of chemicals from heterogeneous biomass
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Production of chemicals from lignocellulosic biomass has been proposed as a suitable replacement to petrochemicals. However, one inherent challenge of biomass utilization is the heterogeneity of the substrate resulting in the presence of mixed sugars after hydrolysis. Fermentation of mixed sugars often leads to poor yield and generation of multiple by-products, thus complicating the subsequent downstream processing. System biocatalysis has thus been developed in recent years to address this challenge. In this work, several novel enzymes with broad substrate promiscuity were identified using a sequence-based discovery approach as suitable biocatalysts in a conversion ofd-xylose andl-arabinose, two major constituents of hemicellulose found in plant biomass. These promiscuous enzymes enabled simultaneous biotransformation ofd-xylose andl-arabinose to yield 1,4-butanediol (BDO) with a maximum production rate of 3 g L?1h?1and a yield of >95%. This model system was further adapted toward the production of α-ketoglutarate (2-KG) from the pentoses using O2as a cosubstrate for cofactor recycling reaching a maximum production rate of 4.2 g L?1h?1and a yield of 99%. To verify the potential applicability of our system, we attempted to scale up the BDO and 2-KG production fromd-xylose andl-arabinose. Simple optimization and reaction engineering allowed us to obtain BDO and 2-KG titers of 18 g L?1and 42 g L?1, with theoretical yields of >75% and >99%, respectively. One of the promiscuous enzymes identified together with auxiliary promiscuous enzymes was also suitable for stereoconvergent synthesis from a mixture ofd-glucose andd-galactose, predominant sugars found in food waste streams and microalgae biomass.
- Pick, André,Sieber, Volker,Sutiono, Samuel
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supporting information
p. 3656 - 3663
(2021/06/06)
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- Efficient photocatalytic conversion of CH4into ethanol with O2over nitrogen vacancy-rich carbon nitride at room temperature
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A record ethanol production rate of 281.6 μmol g?1h?1for the photocatalytic conversion of methane over nitrogen vacancy-rich carbon nitride at room temperature was achieved. Systematic studies demonstrate that the CH4was activated by the highly reactive ˙OH radicals generated,viaH2O2, from the photo-reduction of O2with H2O.
- Yang, Zhongshan,Zhang, Qiqi,Ren, Liteng,Chen, Xin,Wang, Defa,Liu, Lequan,Ye, Jinhua
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supporting information
p. 871 - 874
(2021/02/06)
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- Highly selective conversion of methane to ethanol over CuFe2O4-carbon nanotube catalysts at low temperature
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Conversion of methane into liquid alcohol such as ethanol at low temperature in a straight, selective and low energy consumption process remains a topic of intense scientific research but a great challenge. In this work, CuFe2O4/CNT composite is successfully synthesized via a facile co-reduction method and used as catalysts to selectively oxidize methane. At a low temperature of 150 °C, methane is directly converted to ethanol in a single process on the as-prepared CuFe2O4/CNT composite with high selectivity. A mechanism is also proposed for the significant methane selective oxidation performance of the CuFe2O4/CNT composite catalysts.
- Fu, Xian-Zhu,Luo, Jing-Li,Shen, Xinquan,Wu, Dan
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supporting information
(2021/09/15)
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- MOF-derived hcp-Co nanoparticles encapsulated in ultrathin graphene for carboxylic acids hydrogenation to alcohols
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Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH2CO* followed by consecutive hydrogenation to RCH2CH2OH through RCH2COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation.
- Dong, Mei,Fan, Weibin,Gao, Xiaoqing,Zhu, Shanhui
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p. 201 - 211
(2021/06/03)
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- METHOD FOR PRODUCING BIO ALCOHOL FROM INTERMEDIATE PRODUCTS OF ANAEROBIC DIGESTION TANK
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The present invention relates to a method for producing a bio-alcohol by reacting a mixture of volatile fatty acid with methanol in 2 through 11 in a reactor in the presence of a 280 °C-membered alkaline earth metal catalyst or 400 °C transition metal catalyst formed based on a support.
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Paragraph 0057-0060; 0063; 0065-0066; 0068-0069; 0071
(2021/05/25)
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- Transition Metal-Free Direct Hydrogenation of Esters via a Frustrated Lewis Pair
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"Frustrated Lewis pairs"(FLPs) continue to exhibit unique reactivity for the reduction of organic substrates, yet to date, the catalytic hydrogenation of an ester functionality has not been demonstrated. Here, we report that iPr3SnNTf2 (1-NTf2; Tf = SO2CF3) is a more potent Lewis acid than the previously studied iPr3SnOTf; in an FLP with 2,4,6-collidine/2,6-lutidine (col/lut), this translates to faster H2 activation and the catalytic hydrogenolysis of an ester bond by a main-group compound, furnishing alcohol and ether (minor) products. The reaction outcome is sensitive to the steric and electronic properties of the substrate; CF3CO2Et and simple formates (HCO2Me and HCO2Et) are catalytically reduced, whereas related esters CF3CO2nBu and CH3CO2Et show only stoichiometric reactivity. A computational case study on the hydrogenation of CF3CO2Et and CH3CO2Et reveals that both share a common mechanistic pathway; however, key differences in the energies of a Sn-acetal intermediate and transition states emerge, favoring CF3CO2Et reduction. The alcohol products reversibly inhibit 1-NTf2/lut via formation of resting-state species 1-OR/[1·(1-OR)]+[NTf2]- however, the extra energy required to regenerate 1-NTf2/lut exacerbates the unfavorable reduction energy profile for CH3CO2Et, ultimately preventing turnover. These findings will assist the design of future main-group catalysts for ester hydrogenation, with improved performance.
- Sapsford, Joshua S.,Csókás, Dániel,Turnell-Ritson, Roland C.,Parkin, Liam A.,Crawford, Andrew D.,Pápai, Imre,Ashley, Andrew E.
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p. 9143 - 9150
(2021/07/31)
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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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- Highly efficient visible-light photocatalytic ethane oxidation into ethyl hydroperoxide as a radical reservoir
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Photocatalytic ethane conversion into value-added chemicals is a great challenge especially under visible light irradiation. The production of ethyl hydroperoxide (CH3CH2OOH), which is a promising radical reservoir for regulating the oxidative stress in cells, is even more challenging due to its facile decomposition. Here, we demonstrated a design of a highly efficient visible-light-responsive photocatalyst, Au/WO3, for ethane oxidation into CH3CH2OOH, achieving an impressive yield of 1887 μmol gcat?1in two hours under visible light irradiation at room temperature for the first time. Furthermore, thermal energy was introduced into the photocatalytic system to increase the driving force for ethane oxidation, enhancing CH3CH2OOH production by six times to 11?233 μmol gcat?1at 100 °C and achieving a significant apparent quantum efficiency of 17.9% at 450 nm. In addition, trapping active species and isotope-labeling reactants revealed the reaction pathway. These findings pave the way for scalable ethane conversion into CH3CH2OOH as a potential anticancer drug.
- Zhu, Yao,Fang, Siyuan,Chen, Shaoqin,Tong, Youjie,Wang, Chunling,Hu, Yun Hang
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p. 5825 - 5833
(2021/05/07)
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- Steric effect induces CO electroreduction to CH4on Cu-Au alloys
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The electrocatalytic reduction of carbon monoxide (CO) is an emerging direction with new catalyst structures, among which the bimetallic component catalysts feature both functional diversity and high-density of active sites. In this work, we demonstrate that the fine tuning of adjacent bimetallic sites can allow us to select different reaction pathways toward C1or C2products in the electroreduction of CO. Cu and Cu-Au alloy catalysts with different atomic ratios were fabricated and investigated for appropriate molecular distances. The pure Cu catalyst was found to be active for electroreducing CO to C2H4, as the adjacent Cu sites were beneficial for adsorbing multiple CO molecules and subsequent C-C coupling. On the other hand, alloying Cu with Au introduced steric hindrance and a larger intermolecular distance between adjacent adsorbed *CO intermediates, thus leading to a decrease of C2H4selectivity but an enhanced CH4pathway. Our work revealed the importance of spacing between active sites for CO electroreduction, which can benefit the catalyst design to further improve activities and selectivities in electrocatalytic CO reduction.
- Guan, Anxiang,Ji, Yali,Li, Si,Qian, Linping,Wang, Qihao,Wu, Limin,Yang, Chao,Zhang, Lijuan,Zheng, Gengfeng
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supporting information
p. 21779 - 21784
(2021/10/12)
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- Synthesis of C2oxygenates from syngas over UiO-66 supported Rh-Mn catalysts: The effect of functional groups
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UiO-66 and its modified forms (UiO-66-NH2 and UiO-66-OH) were used as supports to prepare Rh-Mn catalysts by using a co-impregnation method, and their catalytic activities were investigated for the direct synthesis of ethanol-based C2+ oxygenates from CO hydrogenation. The catalysts were comprehensively characterized using N2 sorption, XRD, XPS, DRIFT, and TPSR analyses. The structural and textural properties of the catalysts clearly show that Rh and Mn are highly dispersed in the pores of MOFs, but the order of the original structure is partially sacrificed due to the loading of metals and the synergistic effect of Rh, Mn, and Zr would be influenced by various functional groups present in UiO-66. On combining both in situ FT-IR and TPSR analyses, it is confirmed that the higher number of active sites of Rh0 on RM/UiO-66 promotes the CO dissociation ability and hydrogenation rate, which result in its best catalytic activity with the highest yield of C2+ oxygenates, 197.3 g (kg h)-1. This journal is
- Han, Ying,Yu, Jun,Guo, Qiangsheng,Xiao, Xiuzhen,Guo, Xiaoming,Mao, Haifang,Mao, Dongsen
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p. 696 - 704
(2021/01/25)
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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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- Cu active sites confined in MgAl layered double hydroxide for hydrogenation of dimethyl oxalate to ethanol
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The dimethyl oxalate (DMO) hydrogenation reaction is the key step of indirect synthesis of C2-C4 oxygenates (e.g., ethanol) from syngas. Copper-based catalysts have been extensively explored for DMO hydrogenation. However, the unstable copper active sites induced by metal-particle growth at high rection temperatures (e.g., > 553 K) is an impediment to the stable performance. Herein, we report a facile co-precipitation method to confine Cu active sites in the layered double hydroxide for the hydrogenation of DMO to ethanol. The effects of Mg/Al molar ratio on the catalytic performance were systematically investigated to get insights into the structure-activity relationship. The results indicate that the CuMgAl-LDH-1.25 catalyst possesses regular lamellar structures, highly dispersed Cu active sites, and moderate acidic sites, which synergistically achieves a stable performance with a DMO conversion of ca. 100 % and ethanol selectivity exceeding 83 % at 553 K, 3 MPa.
- Shi, Jianzhe,He, Yan,Ma, Kui,Tang, Siyang,Liu, Changjun,Yue, Hairong,Liang, Bin
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p. 318 - 326
(2020/04/29)
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- Influence of La-doping on the CuO/ZrO2catalysts with different Cu contents for hydrogenation of dimethyl oxalate to ethylene glycol
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Herein, Cu/ZrO2catalysts containing different Cu contents with or without La-doping were used for the selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Effects of La addition and the optimal Cu content were thoroughly investigated. It was found that the Cu0/Cu+pairs located at interfacial sites for CuO/ZrO2catalysts with different Cu contents played an important role in the hydrogenation of DMO to EG. Interestingly, the La-doping could make the copper dispersion increase obviously. Besides, it greatly inhibited the crystal phase transformation from tetragonal to monoclinic zirconia regardless of being calcined at 750 °C. Meanwhile, the incorporation of La promoted the activation of hydrogen although resulting in a small increase in acidic/basic sites over the catalyst surface, which led to a higher conversion of DMO while the selectivity of EG decreased slightly. As a result, 97.2% selectivity of EG, which corresponds to 100% conversion of DMO, was achieved over the La-doped CuO/ZrO2catalyst with 33 wt% Cu content, which was also stable for more than 168 h on stream. This results revealed that the strong interaction between La promoters and Cu species was another type of important active site with high catalytic efficiency in addition to the Cu0/Cu+site of La-doped CuO/ZrO2?catalyst.
- Ding, Jian,Guo, Xiaohui,Liu, Huimin,Wang, Meihui,Wang, Yaxiong,Wang, Zhenfeng,Yu, Gewen
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p. 18102 - 18113
(2021/10/12)
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- Hidden Mechanism Behind the Roughness-Enhanced Selectivity of Carbon Monoxide Electrocatalytic Reduction
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High roughness has been proved to be an effective design strategy for electrocatalyst in many systems. Especially, high selectivity of carbon monoxide reduction (CORR) in competition with the hydrogen evolution reaction has been observed on high roughness electrocatalysts. However, the two well-known mechanisms, i.e., decreasing the energy barrier of CORR and increasing local pH, failed to understand the roughness-enhanced selectivity in a recent experiment. Herein we unravel the hidden mechanism by establishing a comprehensive kinetic model for CORR on catalysts with different roughness factors. We conclude that the roughness-enhanced CORR selectivity is actually kinetic controlled by local-electric-field-directed mass transfer of adsorbed species on the electrode surface. Several ways to optimize CORR selectivity are predicted. Our work highlights the kinetics in electrocatalysis on nanocatalysts, and provides a conceptually new principle for future catalyst design.
- Liu, Yinghuan,Jiang, Huijun,Hou, Zhonghuai
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supporting information
p. 11133 - 11137
(2021/04/16)
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- Highly active carbon nanotube–promoted Rh-Mn-Li/SiO2 catalysts for the synthesis of C2+ oxygenates from syngas
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The effect of carbon nanotubes on the catalytic properties of Rh-Mn-Li/SiO2 catalysts was investigated for CO hydrogenation. The catalysts were comprehensively characterized by means of X-ray power diffraction, N2 sorption, transmission electron microscope, H2–temperature-programmed reduction, CO–temperature-programmed desorption, temperature-programmed surface reaction, and X-ray photoelectron spectroscopy. The results showed that an appropriate amount of carbon nanotubes can be attached to the surface of the SiO2 sphere and can improve the Rh dispersion. Moderate Rh-Mn interaction can be obtained by doping with the appropriate amount of carbon nanotubes, which promotes the formation of strongly adsorbed CO and facilitates the progress of CO insertion, resulting in the increase in the selectivity of C2+ oxygenate synthesis.
- Chen, Guoqing,Han, Ying,Mao, Dongsen,Mao, Haifang,Xiao, Xiuzhen,Yu, Jun
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p. 436 - 442
(2021/01/11)
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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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- 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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- The cascade catalysis of the porphyrinic zirconium metal-organic framework PCN-224-Cu for CO2conversion to alcohols
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Reproducing the highly efficient catalytic cascade system to mimic life behaviorsin vitrohas been intensively investigated over the past few decades. However, except for biocatalysis with enzymes, most chemocatalytic cascades in essence combine several reactions that occur over mutually independent catalytic sites in a container. Herein, with a series of control experiments and stepwise theoretical derivation based on the calculations of density functional theory and a semi-empirical method, a generalized cascade catalysis is discovered for the chemocatalytic conversion of CO2to higher alcohols over a porphyrinic zirconium metal-organic framework, PCN-224-Cu. Two types of catalytic sites in PCN-224-Cu,i.e., the Zr6cluster and TCPP-Cu unit, act like organelles, which can complete a class of reactions instead of particular one. The Zr6cluster is in charge of molecular dissociation, while the TCPP-Cu unit is responsible for molecular assembly. Therefore, semi-finished intermediates repeatedly transfer between the two types of catalytic sites until the ultimate formation of ethanol with high efficiency (ethanol yield, 4.53 mmol h?1gcat.?1at 403 K) and selectivity (～100%).
- Liu, Xiao-Qin,Lu, Xiao-Jie,Qi, Shi-Chao,Sun, Lin-Bing,Xue, Ding-Ming,Yang, Zhi-Hui,Zhu, Rong-Rong
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p. 24510 - 24516
(2021/11/17)
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- Selective electroreduction of CO2to ethanol over a highly stable catalyst derived from polyaniline/CuBi2O4
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Electroreduction of CO2 to ethanol with high stability and selectivity is vital for resourceful CO2 utilization. The catalyst derived from PANi/CuBi2O4via an electrochemical activation process shows high faraday efficiency (FE) for the electroreduction of CO2 to ethanol (～64.15%). Repeated redox reaction generated the evolutionary surface of PANi/CuBi2O4 with Cu0+ and Bi0+ crossed. Owing to the high priority of the adsorbed O-terminal on the introduced Bi, which is located on the Cu surface, the CO2RR pathway for ethylene is suppressed after C-C coupling, making PANi/CuBi2O4 more likely to produce ethanol. With our thorough investigation of the PANi/CuBi2O4 composite system, the agglomerate behaviour of the catalyst in the activation process can be effectively suppressed leading to the high stability and long lifetime of the catalyst. Our findings highlight the importance of local surface evolution by electrochemical pretreatment while retaining the excellent property by stabilizing the main body of the catalyst.
- Du, Jun,He, Anbang,Li, Hui,Liu, Zuohua,Tao, Changyuan,Yang, Ming,Yang, Yong,Zou, Qian
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p. 5908 - 5916
(2021/09/10)
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- A mild and selective Cu(II) salts-catalyzed reduction of nitro, azo, azoxy, N-aryl hydroxylamine, nitroso, acid halide, ester, and azide compounds using hydrogen surrogacy of sodium borohydride
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The first mild, in situ, single-pot, high-yielding well-screened copper (II) salt-based catalyst system utilizing the hydrogen surrogacy of sodium borohydride for selective hydrogenation of a broad range of nitro substrates into the corresponding amine under habitancy of water or methanol like green solvents have been described. Moreover, this catalytic system can also activate various functional groups for hydride reduction within prompted time, with low catalyst-loading, without any requirement of high pressure or molecular hydrogen supply. Notably, this system explores a great potential to substitute expensive traditional hydrogenation methodologies and thus offers a greener and simple hydrogenative strategy in the field of organic synthesis.
- Kalola, Anirudhdha G.,Prasad, Pratibha,Mokariya, Jaydeep A.,Patel, Manish P.
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supporting information
p. 3565 - 3589
(2021/10/12)
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- Cyclohexene esterification-hydrogenation for efficient production of cyclohexanol
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A novel process based on cyclohexene esterification-hydrogenation for the production of cyclohexanol, the key intermediate in the production of ε-caprolactam, was devised and validated for the first time. In this process, cyclohexene obtained from the partial hydrogenation of benzene is esterified with acetic acid to cyclohexyl acetate, followed by hydrogenation to cyclohexanol. The experimentally determined equilibrium conversion of cyclohexene for cyclohexene esterification at the stoichiometric ratio is always ≥68% in the temperature range of 333-373 K over the commercial Amberlyst 15 catalyst, which is substantially higher than that of cyclohexene hydration. The apparent activation energy (Ea) for the esterification of cyclohexene with acetic acid is 60.0 kJ mol?1, which is lower than that of cyclohexene hydration. In the hydrogenation of cyclohexyl acetate to cyclohexanol, high conversion of 99.5% and high selectivity of 99.7% are obtained on the La-promoted Cu/ZnO/SiO2catalyst prepared by the co-precipitation method. This process shows both a high overall atom economy of 99.4% comparable to that of the cyclohexene hydration process and a much higher catalytic efficiency than the phenol hydrogenation process. On the basis of the above fundamental works, a pilot-scale demonstration unit with a capacity of 8000 tonnes per annum was developed and operated smoothly for more than 1000 h with no indication of deactivation.
- Zhu, Yunfeng,Gao, Liang,Wen, Langyou,Zong, Baoning,Wang, Hao,Qiao, Minghua
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supporting information
p. 1185 - 1192
(2021/02/26)
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- Efficient Synthesis of Cyclohexanol and Ethanol via the Hydrogenation of Acetic Acid-Derived Cyclohexyl Acetate with the CuxAl1Mn2?x Catalysts
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The hydrogenation of cyclohexyl acetate (CHA), derived from the esterification of acetic acid and cyclohexene, not only alleviates the overcapacity of acetic acid, but also produces value-added cyclohexanol (CHOL) and ethanol at a low cost. Herein, we prepared Cu1Al1, Cu1Mn1 and CuxAl1Mn2?x catalysts via a deposition-precipitation method for the hydrogenation of CHA to CHOL and ethanol. As a result, the ternary CuxAl1Mn2?x catalysts exhibited superior behaviors to Cu1Al1 and Cu1Mn1. To our delight, Cu1Al1Mn1 had a 95.0 % CHA conversion and 93.6 % selectivity to CHOL along with 97.6 % selectivity to ethanol in a batch reactor. Based on detailed characterization, the ternary CuxAl1Mn2?x catalysts possessed more uniformed dispersion of Cu particles, less aggregation and larger BET specific surface area than the binary catalysts. Furthermore, Cu1Al1Mn1 possessed the highest Cu0/(Cu0+Cu+) molar ratio, the highest (Mn2++Mn3+)/Mn4+ molar ratio and the most abundant surface oxygen vacancies, facilitating the adsorption and activation of CHA and hydrogen. In addition, Cu1Al1Mn1 had excellent stability (>500 h) in a fixed-bed reactor.
- Song, Tongyang,Chen, Wei,Qi, Yuanyuan,Wu, Peng,Zhu, Zhirong,Li, Xiaohong
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p. 3099 - 3111
(2021/05/19)
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- Hydrogen-Catalyzed Acid Transformation for the Hydration of Alkenes and Epoxy Alkanes over Co-N Frustrated Lewis Pair Surfaces
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Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ-Co-N-Hδ+ and then be converted into OHδ-Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.
- Deng, Qiang,Deng, Shuguang,Gao, Ruijie,Li, Xiang,Tsang, Shik Chi Edman,Wang, Jun,Zeng, Zheling,Zou, Ji-Jun
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p. 21294 - 21301
(2021/12/17)
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- Coupling of Cu(100) and (110) Facets Promotes Carbon Dioxide Conversion to Hydrocarbons and Alcohols
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Copper can efficiently electro-catalyze carbon dioxide reduction to C2+ products (C2H4, C2H5OH, n-propanol). However, the correlation between the activity and active sites remains ambiguous, impeding further improvements in their performance. The facet effect of copper crystals to promote CO adsorption and C?C coupling and consequently yield a superior selectivity for C2+ products is described. We achieve a high Faradaic efficiency (FE) of 87 % and a large partial current density of 217 mA cm?2 toward C2+ products on Cu(OH)2-D at only ?0.54 V versus the reversible hydrogen electrode in a flow-cell electrolyzer. With further coupled to a Si solar cell, record-high solar conversion efficiencies of 4.47 % and 6.4 % are achieved for C2H4 and C2+ products, respectively. This study provides an in-depth understanding of the selective formation of C2+ products on Cu and paves the way for the practical application of electrocatalytic or solar-driven CO2 reduction.
- Zhong, Dazhong,Zhao, Zhi-Jian,Zhao, Qiang,Cheng, Dongfang,Liu, Bin,Zhang, Gong,Deng, Wanyu,Dong, Hao,Zhang, Lei,Li, Jingkun,Li, Jinping,Gong, Jinlong
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supporting information
p. 4879 - 4885
(2021/01/20)
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- High-Rate CO2 Electroreduction to C2+ Products over a Copper-Copper Iodide Catalyst
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Electrochemical CO2 reduction reaction (CO2RR) to multicarbon hydrocarbon and oxygenate (C2+) products with high energy density and wide availability is of great importance, as it provides a promising way to achieve the renewable energy storage and close the carbon cycle. Herein we design a Cu-CuI composite catalyst with abundant Cu0/Cu+ interfaces by physically mixing Cu nanoparticles and CuI powders. The composite catalyst achieves a remarkable C2+ partial current density of 591 mA cm?2 at ?1.0 V vs. reversible hydrogen electrode in a flow cell, substantially higher than Cu (329 mA cm?2) and CuI (96 mA cm?2) counterparts. Induced by alkaline electrolyte and applied potential, the Cu-CuI composite catalyst undergoes significant reconstruction under CO2RR conditions. The high-rate C2+ production over Cu-CuI is ascribed to the presence of residual Cu+ and adsorbed iodine species which improve CO adsorption and facilitate C?C coupling.
- Li, Hefei,Liu, Tianfu,Wei, Pengfei,Lin, Long,Gao, Dunfeng,Wang, Guoxiong,Bao, Xinhe
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supporting information
p. 14329 - 14333
(2021/05/19)
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- Micro-Electrode with Fast Mass Transport for Enhancing Selectivity of Carbonaceous Products in Electrochemical CO2 Reduction
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During electrochemical carbon dioxide (CO2) reduction on copper electrodes in an aqueous electrolyte, one of the key challenges is the competition between hydrogen evolution and CO2 reduction, especially under large current density. Here, micro-electrodes are designed with a copper wire as the substrate, which shows improved mass transport compared to the planar electrode. The Faradaic efficiency for C2+ products reaches 79% with a partial geometric current density ?77.7?mA?cm?2 on Cu2O nanowire/micro-electrode, which is 3.7?times higher than Cu2O nanowire/planar-electrode. The authors also designed CuO and metallic Cu with micro-electrode as substrate and observed enhanced selectivity for carbonaceous products, proving the universality of the concept. The improved activity is attributed to the fast mass transport of CO2 to the catalytic interface and thus the suppression of hydrogen production.
- Zhang, Qixing,Ren, Dan,Pan, Sanjiang,Wang, Manjing,Luo, Jingshan,Zhao, Ying,Gr?tzel, Michael,Zhang, Xiaodan
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- The site pair matching of a tandem Au/CuO-CuO nanocatalyst for promoting the selective electrolysis of CO2to C2products
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Tandem catalysis, in which a CO2-to-C2 process is divided into a CO2-to-CO/?CO step and a CO/?CO-to-C2 step, is promising for enhancing the C2 product selectivity when using Cu-based electrochemical CO2 reduction catalysts. In this work, a nanoporous hollow Au/CuO-CuO tandem catalyst was used for catalyzing the eCO2RR, which exhibited a C2 product FE of 52.8% at -1.0 V vs. RHE and a C2 product partial current density of 78.77 mA cm-2 at -1.5 V vs. RHE. In addition, the C2 product FE stably remained at over 40% over a wide potential range, from -1.0 V to -1.5 V. This superior performance was attributed to good matching in terms of the optimal working potential and charge-transfer resistance between CO/?CO-production sites (Au/CuO) and CO/?CO-reduction sites (CuO). This site pair matching effect ensured sufficient supplies of CO/?CO and electrons at CuO sites at the working potentials, thus dramatically enhancing the formation rate of C2 products. This journal is
- Sun, Xiao-Chen,Yin, Hai-Jing,Yuan, Chen-Yue,Yuan, Kun,Zhang, Ya-Wen,Zheng, Ya-Li,Zhou, Jun-Hao
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p. 38486 - 38494
(2021/12/20)
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- Vanadium oxide integrated on hierarchically nanoporous copper for efficient electroreduction of CO2to ethanol
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The electrochemical reduction of CO2to an ethanol product is regarded as a highly promising route for CO2utilization. However, the poor selectivity is still a critical challenge for increasing the yield of the specific ethanol. As a CO2reduction catalyst, the hierarchically nanoporous copper integrated with vanadium oxide can achieve a 30.1% faradaic efficiency for CO2-to-ethanol production and an ethanol partial current density of ?16 mA cm?2at ?0.62 Vvs.RHE, corresponding to a 4-fold increase in activity compared to bare nanoporous Cu. It even delivers an ethanol partial current density that exceeds ?39 mA cm?2at ?0.8 Vvs.RHE in a flow-cell reactor. The hierarchically nanoporous Cu skeleton not only facilitates both electron and electrolyte transport but also provides a large specific surface area for high active site density. Density functional theory reveals that the vanadium oxide decorated Cu surface can facilitate water dissociation and optimize the hydrogen adsorption energy on Cu, lowering the energy barrier for the protonation of carbon dioxide and C-C coupling. Meanwhile, it can increase hydrogen proton coverage on the catalyst surface and inhibit dehydration, which are beneficial for breaking the C=C bond of the *HCCOH intermediate, thus enhancing the faradaic efficiency of ethanol significantly. The highly efficient conversion of CO2to ethanol demonstrates that the hybrid electrocatalyst is considered as a promising candidate for practical electrocatalytic CO2RR applications.
- Yang, Qingcheng,Liu, Xunlin,Peng, Wei,Zhao, Yang,Liu, Zhixiao,Peng, Ming,Lu, Ying-Rui,Chan, Ting-Shan,Xu, Xiandong,Tan, Yongwen
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supporting information
p. 3044 - 3051
(2021/02/16)
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- Insights into the electrochemical degradation of phenolic lignin model compounds in a protic ionic liquid-water system
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Cleavage of aryl ether (Caryl-O) bonds is crucial for the conversion and value-added utilization of lignin and its derivatives, but remains extremely challenging under mild conditions due to strong Caryl-O linkages. In this study, the Caryl-O bond breaking is achieved through electrocatalytic oxidation of four phenolic lignin model compounds with typical Caryl-O bonds,i.e., 4-ethoxyphenol (EP), 4-phenoxyphenol (PP),p-benzyloxyphenol (PBP), and 2-(2-phenylethoxy)phenol (2-PEP), in a protic ionic liquid [BSO3Hmim][OTf]-H2O electrolyte, and the electrocatalytic oxidation mechanism is also fully explored. The effects of H2O on the viscosity and conductivity of the [BSO3Hmim][OTf] ionic liquid system, as well as the solubility and diffusion coefficients of O2and the four lignin substrates, are investigated to optimize the optimal ratio of the electrolyte system composed of [BSO3Hmim][OTf] and H2O. Electrochemical oxidation-reduction behaviors of the four lignin substrates in the [BSO3Hmim][OTf]-H2O system and the effect of O2and N2atmospheres on degradation are studied in detail by using cyclic voltammetry (CV) curves. Finally, by combining the analysis of degradation products with isotope labeling experiments, the C-O bond cleavage mechanism is obtained, which mainly involves direct and indirect oxidation. Specifically, under a N2atmosphere, the substrates are oxidized directly on the RuO2-IrO2/Ti mesh electrode through Caryl-O bond splitting to form quinone and carbonium ions, while under an O2atmosphere, apart from the direct oxidation on the electrode, indirect oxidation of the lignin substrates also occurs throughin situgenerated H2O2. This study may provide some insight into developing effective strategies for efficient utilization of lignin under mild conditions.
- Liu, Guangyong,Wang, Qian,Yan, Dongxia,Zhang, Yaqin,Wang, Chenlu,Liang, Shijing,Jiang, Lilong,He, Hongyan
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p. 1665 - 1677
(2021/03/09)
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- PROCESS FOR ISOBUTANOL PRODUCTION FROM ETHANOL AND SYNGAS
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Processes for converting ethanol and syngas (CO and H2) to isobutanol are disclosed. Syngas and ethanol are reacted in the first reaction zone in the presence of a first heterogeneous catalyst to produce a first reactor effluent comprising a first mixture of alcohols. The first reactor effluent is reacted a second reaction zone in the presence of a second heterogeneous catalyst to produce a second reactor effluent comprising a second mixture of alcohols. The second reactor effluent is separated into an overhead gas stream and a liquid bottom stream. The liquid bottom stream is separated into at least a C1-2 stream, a C3 stream, and a C4+ stream. The isobutanol is recovered from the C4+ stream.
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Page/Page column 10
(2021/04/01)
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- Reconstructing two-dimensional defects in CuO nanowires for efficient CO2electroreduction to ethylene
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Here we report that in situ reconstructed Cu two-dimensional (2D) defects in CuO nanowires during CO2RR lead to significantly enhanced activity and selectivity of C2H4 compared to the CuO nanoplatelets. Specifically, the CuO nanowires achieve high faradaic efficiency of 62% for C2H4 and a partial current density of 324 mA cm-2 yet at a low potential of -0.56 V versus a reversible hydrogen electrode. Structural evolution characterization and in situ Raman spectra reveal that the high yield of C2H4 on CuO nanowires is attributed to the in situ reduction of CuO to Cu followed by structural reconstruction to form 2D defects, e.g., stacking faults and twin boundaries, which improve the CO production rate and ?CO adsorption strength. This finding may provide a paradigm for the rational design of nanostructured catalysts for efficient CO2 electroreduction to C2H4.
- Li, Zhengyuan,Wang, Yan,Wu, Jingjie,Wu, Yucheng,Xia, Shuai,Zhang, Jianfang,Zhang, Tianyu
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supporting information
p. 8276 - 8279
(2021/08/25)
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- Machine-Learning-Guided Discovery and Optimization of Additives in Preparing Cu Catalysts for CO2Reduction
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Discovery and optimization of new catalysts can be potentially accelerated by efficient data analysis using machine-learning (ML). In this paper, we record the process of searching for additives in the electrochemical deposition of Cu catalysts for CO2 reduction (CO2RR) using ML, which includes three iterative cycles: "experimental test; ML analysis; prediction and redesign". Cu catalysts are known for CO2RR to obtain a range of products including C1 (CO, HCOOH, CH4, CH3OH) and C2+ (C2H4, C2H6, C2H5OH, C3H7OH). Subtle changes in morphology and surface structure of the catalysts caused by additives in catalyst preparation can lead to dramatic shifts in CO2RR selectivity. After several ML cycles, we obtained catalysts selective for CO, HCOOH, and C2+ products. This catalyst discovery process highlights the potential of ML to accelerate material development by efficiently extracting information from a limited number of experimental data.
- Guo, Ying,He, Xinru,Su, Yuming,Dai, Yiheng,Xie, Mingcan,Yang, Shuangli,Chen, Jiawei,Wang, Kun,Zhou, Da,Wang, Cheng
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supporting information
p. 5755 - 5762
(2021/05/07)
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- Promoting carbon dioxide electroreduction toward ethanol through loading Au nanoparticles on hollow Cu2O nanospheres
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Electrochemical CO2 reduction (CO2RR) to ethanol is a way to advance CO2 utilization toward a renewable chemical feedstock and fuel. In present study, an approach to promote ethanol production is employed through adding Au, which is favorable toward CO formation, onto Cu2O catalysts. Namely, the Cu2O hollow nanospheres with a size of 150?180 nm were synthesized by a soft template method, and then Au nanoparticles of ～7 nm were loaded to obtain Aux/Cu2O composites. The Aux/Cu2O catalysts have an earlier onset for ethanol production than Cu2O. Besides, Aux/Cu2O catalysts display the significantly enhanced Faraday efficiencies (FEs) of CO and ethanol, the suppressed hydrogen evolution reaction and the slightly weakened HCOOH formation. Among them, Au0.17/Cu2O stands out with the highest FEs of ethanol from 10.8%–16.2% throughout the measuring potentials, suggesting an optimal amount of Au. Furthermore, it is found that the FEs of ethanol increase as the atomic ratio of Au/Cu increases at the medium reduction potentials (-1.1 V to -1.3 V). Besides, it is demonstrated that ethanol formation is more favorable over ethylene formation, evidenced by the ratio of FEethanol/FEethylene reaching 2.0, 3.3, 4.1 on three Aux/Cu2O catalysts, respectively. This correlation between the ethanol production and the Au amount reflects that Au plays a crucial role in promoting ethanol formation. The enhanced ethanol formation is ascribed to more CO formation on Au sites to promote C–C coupling. Our study demonstrates an effective approach to develop Cu-based electrocatalysts for ethanol formation from CO2.
- Zhang, Lijie,Li, Mei,Zhang, Shengbo,Cao, Xuerui,Bo, Jinxiao,Zhu, Xinli,Han, Jinyu,Ge, Qingfeng,Wang, Hua
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p. 348 - 356
(2020/09/04)
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- The effect of supports on hydrogenation and water-tolerance of copper-based catalysts
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The effect of supports (SiO2, ZnO, ZrO2 and Al2O3) on the hydrogenation and water-tolerance of copper catalysts were studied at reaction condition containing water. The copper catalysts with different supports showed different hydrogenation and water-tolerance performances. The result of XRD, BET, Raman, TPR, XPS, N2O titration and TEM confirmed the interactions between copper and supports, and the formation of Cu-MxOy (M = Zn, Zr, and Al) interfaces had great effects on the catalytic activity and water-tolerance performance. In particular, too strong interactions suppressed the reduction of copper oxides, resulting in a low catalytic activity. Nevertheless, the formation of Cu-MxOy could provide more active sites, which provided more chances for the reactants to touch the active sites. By this method, the loss of active sites due to competitive adsorption between water and ethyl acetate could be made up, so that the water-tolerance of copper catalysts was improved.
- Chen, Zheng,Zhao, Xueying,Wei, Shuwei,Wang, Dengfeng,Zhang, Xuelan
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supporting information
p. 9967 - 9974
(2021/06/15)
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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.
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Paragraph 0111
(2021/03/19)
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- Size-Dependent Activity and Selectivity of Atomic-Level Copper Nanoclusters during CO/CO2 Electroreduction
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As a favorite descriptor, the size effect of Cu-based catalysts has been regularly utilized for activity and selectivity regulation toward CO2/CO electroreduction reactions (CO2/CORR). However, little progress has been made in regulating the size of Cu nanoclusters at the atomic level. Herein, the size-gradient Cu catalysts from single atoms (SAs) to subnanometric clusters (SCs, 0.5–1 nm) to nanoclusters (NCs, 1–1.5 nm) on graphdiyne matrix are readily prepared via an acetylenic-bond-directed site-trapping approach. Electrocatalytic measurements show a significant size effect in both the activity and selectivity toward CO2/CORR. Increasing the size of Cu nanoclusters will improve catalytic activity and selectivity toward C2+ productions in CORR. A high C2+ conversion rate of 312 mA cm?2 with the Faradaic efficiency of 91.2 % are achieved at ?1.0 V versus reversible hydrogen electrode (RHE) over Cu NCs. The activity/selectivity-size relations provide a clear understanding of mechanisms in the CO2/CORR at the atomic level.
- Duan, Lele,Hu, Junhui,Ji, Yongfei,Long, Baihua,Rong, Weifeng,Wei, Shuting,Xi, Shibo,Zang, Wenjie,Zou, Haiyuan
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supporting information
p. 466 - 472
(2020/10/29)
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- Oxidative dehydrogenation of ethyl lactate to ethyl pyruvate over vanadium and iron antimonates catalysts
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The oxidative dehydrogenation of ethyl lactate to ethyl pyruvate, corresponding to the first step of a new process in the industrial production of methionine, has been investigated. Iron and vanadium antimonates were developed as catalysts, and were optimized to reach 87 % conversion of ethyl lactate, with 88 % selectivity to ethyl pyruvate, at only 275 °C. The catalysts were characterized before and after catalytic testing, and in situ using various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and XANES spectroscopy. The results show that neither the Sb3+/Sb5+ nor the Fe2+/Fe3+ redox couple were involved in the dehydrogenation of ethyl lactate, or in the catalysts re-oxidation. The active and selective catalytic sites correspond to surface V5+ species. These species should not be considered as part of the bulk oxide, but as supra-surface species whose surface content is monitored with the bulk composition.
- Huchede,Morvan,Vera,Bellière-Baca,Millet
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- Selectivity Control of Cu Nanocrystals in a Gas-Fed Flow Cell through CO2Pulsed Electroreduction
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In this study, we have taken advantage of a pulsed CO2 electroreduction reaction (CO2RR) approach to tune the product distribution at industrially relevant current densities in a gas-fed flow cell. We compared the CO2RR selectivity of Cu catalysts subjected to either potentiostatic conditions (fixed applied potential of -0.7 VRHE) or pulsed electrolysis conditions (1 s pulses at oxidative potentials ranging from Ean = 0.6 to 1.5 VRHE, followed by 1 s pulses at -0.7 VRHE) and identified the main parameters responsible for the enhanced product selectivity observed in the latter case. Herein, two distinct regimes were observed: (i) for Ean = 0.9 VRHE we obtained 10% enhanced C2 product selectivity (FEC2H4 = 43.6% and FEC2H5OH = 19.8%) in comparison to the potentiostatic CO2RR at -0.7 VRHE (FEC2H4 = 40.9% and FEC2H5OH = 11%), (ii) while for Ean = 1.2 VRHE, high CH4 selectivity (FECH4 = 48.3% vs 0.1% at constant -0.7 VRHE) was observed. Operando spectroscopy (XAS, SERS) and ex situ microscopy (SEM and TEM) measurements revealed that these differences in catalyst selectivity can be ascribed to structural modifications and local pH effects. The morphological reconstruction of the catalyst observed after pulsed electrolysis with Ean = 0.9 VRHE, including the presence of highly defective interfaces and grain boundaries, was found to play a key role in the enhancement of the C2 product formation. In turn, pulsed electrolysis with Ean = 1.2 VRHE caused the consumption of OH- species near the catalyst surface, leading to an OH-poor environment favorable for CH4 production.
- Jeon, Hyo Sang,Timoshenko, Janis,Rettenmaier, Clara,Herzog, Antonia,Yoon, Aram,Chee, See Wee,Oener, Sebastian,Hejral, Uta,Haase, Felix T.,Roldan Cuenya, Beatriz
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supporting information
p. 7578 - 7587
(2021/05/26)
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- Br-Doped CuO Multilamellar Mesoporous Nanosheets with Oxygen Vacancies and Cetyltrimethyl Ammonium Cations Adsorption for Optimizing Intermediate Species and Their Adsorption Behaviors toward CO2Electroreduction to Ethanol with a High Faradaic Efficiency
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It is a prospective tactic to actualize the carbon cycle via CO2electroreduction reaction (CO2ER) into ethanol, where the crucial point is to design highly active and selective electrocatalysts. In this work, Br-doped CuO multilamellar mesoporous nanosheets with oxygen vacancies and cetyltrimethyl ammonium (CTA+) cations adsorption were synthesized on Cu foam by one-step liquid-phase method at room temperature. The nanosheets with numerous mesopores and rough edges provided abundant active sites for the adsorption of CO2molecules and brought about a long retention time for intermediates. The dopant of Br-ions induced copious oxygen vacancies on CuO lattices, thereby reducing the activation energy of CO2molecules and optimizing intermediate species and their adsorption behaviors, while adsorbed CTA+cations modulated the O affinity of the Cu sites, favoring *OCH2CH3intermediate converting to ethanol. The optimized Br1.95%-CuO can effectively catalyze CO2ER to C2H5OH in 0.1 M KHCO3. The faradaic efficiency of C2H5OH reached 53.3% with the partial current density of 7.1 mA cm-2at a low potential of ?0.6 V. In addition, after 14 h CO2ER test at ?0.6 V, the current density and faradaic efficiency of C2H5OH on Br1.95%-CuO retained 99.6 and 93.9% of their original values, respectively, indicating its prominent catalytic stability. This work provided a novel strategy for designing a CuO catalyst by nonmetal doping and long-chain organic molecules adsorption with multiple active sites for optimizing intermediate species and their adsorption behaviors toward CO2ER to ethanol.
- Zhang, Wuzhengzhi,Ding, Lianchun,Sun, Weipei,Wu, Zhengcui,Chen, Zheng,Gao, Feng
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p. 14371 - 14381
(2021/09/11)
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- Enhanced CO2 Conversion into Ethanol by Permanently Polarized Hydroxyapatite through C?C Coupling
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Hydroxyapatite (HAp) is a naturally occurring mineral form of calcium apatite of biomedical importance due to its similarity with human hard tissues in morphology and composition. Upon polarization at high temperature, applying 3 kV/cm at 1000 °C, the resulting polarized HAp (p-HAp) exhibits enhanced catalytic behavior due charge accumulation at the interface. More specifically, p-HAp was found to catalyse the conversion of mixtures of CO2(g) and CH4(g) into low carbon organic molecules and into amino acids when N2(g) was added to the mixture. In this work, we report how p-HAp facilitates the conversion of CO2(g) mainly in ethanol by means of forming C?C coupled bonds on its activated surface. After evaluation of a wide range of experimental conditions, we evidence the production of formic acid, methanol and formaldehyde (C1 products); ethanol and acetic acid (C2 products); and acetone (C3 product) from CO2(g) using moderate reaction conditions. Moreover, optimization of the reaction parameters led to a significant increase towards ethanol.
- Sans, Jordi,Sanz, Vanesa,Turon, Pau,Alemán, Carlos
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p. 5025 - 5033
(2021/10/29)
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- More efficient ethanol synthesis from dimethyl ether and syngas over the combined nano-sized ZSM-35 zeolite with CuZnAl catalyst
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Converting syngas into ethanol (EtOH) is highly attractive but remains challenge. Dimethyl ether (DME) carbonylation with CO to methyl acetate (MA) on zeolite and its further hydrogenation to EtOH on Cu-based catalyst open a new EtOH synthesis route from syngas. In this work, a nano-sized ZSM-35 (NZ35) zeolite, possessing abundant active sites and porosity and short diffusion path, is found to realize much better activity of DME to MA than that of the conventional ZSM-35 zeolite (CZ35). In addition, a simple formic-acid-assisted solid-state method is employed for preparation an auto-reduced CuZnAl (CZAargon) catalyst under argon atmosphere. The prepared CZAargon catalyst exhibits an excellent catalytic activity for conversion of produced MA to EtOH. By investigating the effects of different integration manners of NZ35 zeolite and CZAargon catalyst, we find that EtOH can be synthesized only when the NZ35 zeolite and CZAargon catalyst pack in a dual-catalyst bed reactor. After optimizing the reaction conditions for EtOH synthesis with the combination of NZ35 zeolite and CZAargon catalyst, it is found that the DME conversion and MA selectivity are stabilized at 47.0 % and 45.6 % respectively, at 220 °C and 2.5 MPa.
- Feng, Xiaobo,Yao, Jie,Zeng, Yan,Cui, Yu,Kazumi, Shun,Prasert, Reubroycharoen,Liu, Guangbo,Wu, Jinhu,Yang, Guohui,Tsubaki, Noritatsu
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- A New Hexagonal Cobalt Nanosheet Catalyst for Selective CO2Conversion to Ethanal
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We report a new form of catalyst based on ferromagnetic hexagonal-close-packed (hcp) Co nanosheets (NSs) for selective CO2RR to ethanal, CH3CHO. In all reduction potentials tested from ?0.2 to ?1.0 V (vs RHE) in 0.5 M KHCO3solution, the reduction yields ethanal as a major product and ethanol/methanol as minor products. At ?0.4 V, the Faradaic efficiency (FE) for ethanal reaches 60% with current densities of 5.1 mA cm-2and mass activity of 3.4 A g-1(total FE for ethanal/ethanol/methanol is 82%). Density functional theory (DFT) calculations suggest that this high CO2RR selectivity to ethanal on the hcp Co surface is attributed to the unique intralayer electron transfer, which not only promotes [OC-CO]* coupling but also suppresses the complete hydrogenation of the coupling intermediates to ethylene, leading to highly selective formation of CH3CHO.
- Huang, Bolong,Jin, Jing,Lin, Honghong,Ma, Zhenhui,Muzzio, Michelle,Peng, Yong,Shen, Mengqi,Sun, Mingzi,Sun, Shouheng,Xi, Pinxian,Yan, Chun-Hua,Yin, Jie,Yin, Zhouyang,Yu, Chao,Zhang, Hong
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supporting information
p. 15335 - 15343
(2021/10/01)
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- A comparative study of the effects of different TiO2supports toward CO2electrochemical reduction on CuO/TiO2electrode
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CuO-based electrodes possess vast potential in the field of CO2electrochemical reduction. Meantime, TiO2supports show the advantages of being non-toxic, low-cost and having high chemical stability, which render it an ideal electrocatalytic support with CuO. However, different morphologies and structures of TiO2supports can be obtained through various methods, leading to the discrepant electrocatalytic properties of CuO/TiO2. In this paper, three supports, named dense TiO2, TiO2nanotube and TiO2nanofiber, were applied to synthesize CuO/TiO2electrodes by thermal decomposition, and the performances of the electrocatalysts were studied. Results show that the main product of the three electrocatalysts was ethanol, but the electrochemical efficiency and reaction characteristics are obviously different. The liquid product of CuO/Dense TiO2is pure ethanol, however, the current efficiency is rather low owing to the higher resistance of the TiO2film. CuO/TiO2nanotube shows high conductivity and ethanol can be synthesized at low overpotential with high current efficiency, but the gas products cannot be restricted. CuO/TiO2nanofiber has a larger specific surface area and more active sites, which is beneficial for CO2reduction, and the hydrogen evolution reaction can be evidently restricted. The yield of ethanol reaches up to 6.4 μmol cm?2at ?1.1 V (vs.SCE) after 5 h.
- Cao, Huazhen,Jia, Chenxi,Lu, Yueheng,Xu, Shenghang,Zheng, Guoqu
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p. 21805 - 21812
(2021/07/01)
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- Electrochemical Reduction of CO2 Toward C2 Valuables on Cu@Ag Core-Shell Tandem Catalyst with Tunable Shell Thickness
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Electrochemical CO2 reduction reaction (CO2RR) is critical to converting CO2 to high-value multicarbon chemicals. However, the Cu-based catalysts as the only option to reduce CO2 into C2+ products suffer from poor selectivity and low activity. Tandem catalysis for CO2 reduction is an efficient strategy to overcome such problems. Here, Cu@Ag core-shell nanoparticles (NPs) with different silver layer thicknesses are fabricated to realize the tandem catalysis for CO2 conversion by producing CO on Ag shell and further achieving C–C coupling on Cu core. It is found that Cu@Ag-2 NPs with?the proper?thickness of Ag shell exhibit the Faradaic efficiency (FE) of total C2 products and ethylene as high as 67.6% and 32.2% at ?1.1?V (versus reversible hydrogen electrode, RHE), respectively. Moreover, it exhibits remarkably electrocatalytic stability after 14 h. Based on electrochemical tests and CO adsorption capacity analyses, the origin of the enhanced catalytic performance can be attributed to the synergistic effect between Ag shell and Cu core, which strengthens the bonding strength of CO on Cu/Ag interfaces, expedites the charge transfer, increases the electrochemical surface areas (ECSAs). This report provides a Cu-based catalyst to realize efficient C2 generation via a rationally designed core-shell structured catalyst.
- Zhang, Shuaishuai,Zhao, Shulin,Qu, Dongxue,Liu, Xiaojing,Wu, Yuping,Chen, Yuhui,Huang, Wei
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