- Effects of the MoO3 structure of Mo-Sn catalysts on dimethyl ether oxidation to methyl formate under mild conditions
-
The selective oxidation of dimethyl ether (DME) to methyl formate (MF) was conducted in a fixed-bed reactor over the MoO3-SnO2 catalysts with different Mo/Sn ratios. The MF selectivity reached 94.1% and the DME conversion was 33.9% without the formation of COx over the MoSn catalyst at 433 K. The catalysts were deeply characterized by NH3-TPD, CO2-TPD, BET, XPS and H2-TPR. The characterization results showed that different compositions of catalysts obviously affected the surface properties of the catalysts, but the valence of the metal hardly changed with the Mo/Sn ratios. Raman spectroscopy, XRD and XAFS were further used to characterize the structure of the catalysts. The results indicated that the catalyst composition exerted a significant influence on the structure of MoO3. The formation of oligomeric MoO3 and the appropriate coordination numbers of Mo-O at 1.94 ? are the main reasons for the distinct high catalytic activity of the MoSn catalyst. This journal is
- Liu, Guangbo,Zhang, Qingde,Han, Yizhuo,Tsubaki, Noritatsu,Tan, Yisheng
-
-
Read Online
- Surface and catalytic properties of Ce-, Zr-, Au-, Cu-modified SBA-15
-
Au- and CeO2-containing catalysts, supported on SBA-15 mesoporous molecular sieves and loaded with additives such as Cu and Zr species, were obtained and characterised. Cerium oxides are preferentially located in the bulk of SBA-15, whereas Zr species on its surface. Gold and copper loaded on supports strongly interact resulting in the electron transfer from Cu + to metallic gold, thus enhancing redox properties. Moreover, cerium species interact with gold, increasing redox properties of the system. The presence of copper increases the gold dispersion. Ce- and Zr-containing supports contain Lewis acid sites (LAS). The number of LAS is increased by the modification with copper species, whereas gold loading diminishes the LAS content. The presence of Zr species is responsible for Bronsted acidity and directs the oxidation of methanol to dimethyl ether. Copper enhances the selectivity to methyl formate. Gold and cerium are responsible for total oxidation of methanol, which is enhanced by modification with copper. The most attractive catalyst for low temperature total oxidation of methanol is bimetallic AuCu/CeSBA-15.
- Kaminski, Piotr,Ziolek, Maria
-
-
Read Online
- Cu Sub-Nanoparticles on Cu/CeO2 as an Effective Catalyst for Methanol Synthesis from Organic Carbonate by Hydrogenation
-
Cu/CeO2 works as an effective heterogeneous catalyst for hydrogenation of dimethyl carbonate to methanol at 433 K and even at low H2 pressure of 2.5 MPa, and it provided 94% and 98% methanol yield based on the carbonyl and total produced methanol, respectively. This is the first report of high yield synthesis of methanol from DMC by hydrogenation with H2 over heterogeneous catalysts. Characterization of the Cu/CeO2 catalyst demonstrated that reduction of Cu/CeO2 produced Cu metal with 2 surface, which is responsible for the high catalytic performance.
- Tamura, Masazumi,Kitanaka, Takahisa,Nakagawa, Yoshinao,Tomishige, Keiichi
-
-
Read Online
- VAPOR PHASE CARBONYLATION OF METHYL ACETATE, METHANOL, AND DIMETHYL ETHER WITH MOLYBDENUM-ACTIVE CARBON CATALYST
-
A molybdenum-active carbon catalyst was found to catalyze the vapor phase carbonylation of methyl acetate and related compounds under pressurized conditions in the presence of methyl iodide promoter.Acetic anhydride was formed from methyl acetate with an yield of 15percent and a selectivity of 83percent at 250 deg C and 45 atm.The molybdenum-active carbon catalyst was active also for the carbonylation of methanol and dimethyl ether to form methyl acetate.
- Shikada, Tsutomu,Yagita, Hiroshi,Fujimoto, Kaoru,Tominaga, Hiro-o
-
-
Read Online
- Synergetic Behavior of TiO2-Supported Pd(z)Pt(1-z) Catalysts in the Green Synthesis of Methyl Formate
-
Methyl formate (MF) is a valuable platform molecule, the industrial production of which is far from being green. In this contribution, TiO2-supported Pd(z)Pt(1-z) catalysts were found to be effective in the green synthesis of methyl formate (MF) - at T=323 K and ambient pressure - through methanol (MeOH) oxidation. Two series of catalysts with similar bulk Pd/(Pd+Pt) molar ratios, z, were prepared; one by a water-in-oil microemulsion (MicE) method and the other by an incipient wetness impregnation (IWI). The MicE method led to more efficient catalysts owing to a weak influence of z on particle size distributions and nanoparticles composition. Pd(z)Pt(1-z)-MicE catalysts exhibited strong synergistic effects for MF production but weak synergistic effects for MeOH conversion. The catalytic performance of Pd(z)Pt(1-z)-MicE was superior to that of Pd(z)Pt(1-z)-IWI catalysts despite the latter displaying synergetic effects during the reaction. The catalytic behavior of TiO2-supported Pd(z)Pt(1-z) catalysts was explained from correlations between XRD, TEM, and X-ray photoelectron spectroscopy characterizations.
- Baldovino-Medrano, Víctor G.,Pollefeyt, Glenn,Bliznuk, Vitaliy,Van Driessche, Isabel,Gaigneaux, Eric M.,Ruiz, Patricio,Wojcieszak, Robert
-
-
Read Online
- Chemical species active for selective oxygenation of methane with hydrogen peroxide catalyzed by vanadium-containing compounds
-
UV-vis data revealed that monoperoxomonovanadate is an active species for liquid-phase oxygenation of methane with hydrogen peroxide catalyzed vanadium-containing catalysts in trifluoroacetic anhydride.
- Seki, Yasuhiro,Mizuno, Noritaka,Misono, Makoto
-
-
Read Online
- The mechanism of dimethyl carbonate synthesis on Cu-exchanged zeolite Y
-
The mechanism of dimethyl carbonate (DMC) synthesis from oxidative carbonylation of methanol over Cu-exchanged Y zeolite has been investigated using in situ infrared spectroscopy and mass spectrometry under transient-response conditions. The formation of DMC is initiated by reaction of molecularly adsorbed methanol with oxygen to form either mono- or di-methoxide species bound to Cu+ cations. Reaction of the mono-methoxide species with CO produces monomethyl carbonate (MMC) species. DMC is formed via two distinct reaction pathways-CO addition to di-methoxide species or by reaction of methanol with MMC. The rate-limiting step in DMC synthesis is found to be the reaction of CO with mono-methoxide or di-methoxide species. The first of these reactions produces MMC, which then reacts rapidly with methanol to produce DMC, whereas the second of these reactions produces DMC directly. Formaldehyde was identified as an intermediate in the formation of dimethoxy methane (DMM) and methyl formate (MF). Both byproducts are thought to form via a hemiacetal intermediate produced by the reaction of methanol with adsorbed formaldehyde at a Cu+ site.
- Zhang, Yihua,Bell, Alexis T.
-
-
Read Online
- Ester synthesis by NAD(+)-dependent dehydrogenation of hemiacetal: production of methyl formate by cells of methylotrophic yeasts.
-
A water-soluble ester, methyl formate, was detected as a metabolite in the culture medium of methylotrophic yeasts. Methyl formate synthase, which catalyses NAD(+)-dependent dehydrogenation of the hemiacetal adduct of methanol and formaldehyde, catalyses the ester synthesis. The enzyme activity was induced on a methanol medium and was increased further by the addition of formaldehyde. In the reaction system using intact cells of Pichia methanolica AKU 4262, 135 mM (8.1 g/liter) methyl formate was produced from 2 M methanol. This is a new biological process for ester synthesis that couples spontaneous formation of hemiacetal and alcohol dehydrogenase.
- Murdanoto,Sakai,Sembiring,Tani,Kato
-
-
Read Online
- Redox chemistry of gaseous reactants inside photoexcited FeAlPO4 molecular sieve
-
Photochemical studies were conducted to probe the reactivity of the excited Fe-O ligand-to-metal charge-transfer state of the Fe-substituted aluminophosphate sieve with AFI structure (FeAlPO4-5 or FAPO-5), at the gas-micropore interface. Laser light at 350-430 nm was used to excite the metal centers, and low alcohols (methanol, 2-propanol) and O2 were used as donors and electron acceptor, respectively. Subsequent proton transfer and H atom abstraction yielded formaldehyde (acetone) and H2O2, resulting in an overall two-electron transfer process. In these products, acetone was stable in the sieve, while formaldehyde underwent fast Cannizzaro reaction and H2O2 disproportionated to H2O and O2. O2 was efficiently reduced by transient framework Fe+II, indicating that its reduction potential lies at least 0.50 of a volt more than that of a conduction band of dense-phase Fe2O3 particles, which may make available demanding photoreductions not accessible by photochemistry at iron oxide semiconductors materials.
- Ulagappan,Frei
-
-
Read Online
- Structural and reactive relevance of V + Nb coverage on alumina of V{single bond}Nb{single bond}O/Al2O3 catalytic systems
-
Vanadium and niobium species (together and separately) were loaded on gamma alumina, and the resulting catalysts were run in the methanol conversion. This reaction was studied by both GC analysis and FTIR study in the flow system. The catalytic properties are discussed based on the combined FTIR and 27Al, 51V and 1H MAS NMR studies. The NMR studies revealed a different mechanism of interaction between Nb and Al2O3 than that between V and Al2O3. This predetermines the structure of vanadium sites in bimetallic VNb/Al samples. The effect of coverage was considered for various metal loadings ranging from below to above monolayer. One of our most interesting findings is that the surface Nb oxide species exhibited a redox character below monolayer but were acidic above monolayer. 27Al MAS NMR revealed a strong alumina-Nb interaction that may account for its redox performance. Moreover, the role of sulfate from vanadium precursor is evidenced.
- Lewandowska, Anna E.,Banares, Miguel A.,Ziolek, Maria,Khabibulin, Dzhalil F.,Lapina, Olga B.
-
-
Read Online
- Highly active ruthenium complexes with bidentate phosphine ligands for the solvent-free catalytic synthesis of N,N-dimethylformamide and methyl formate
-
Complexes of the type [RuCl2L2] [L = Ph2P(CH2)nPPh2 (n = 1-3), Me2P(CH2)2PMe2] are shown to be highly active and selective catalysts for the synthesis of formic acid derivatives from carbon dioxide, hydrogen and dimethylamine or methanol-triethylamine, respectively, without any additional solvent, affording at 373 K with [RuCl2(dppe)2] an extremely high turnover frequency (TOF) of 360 000 h-1 in N,N-dimethylformamide synthesis and a TOF of 830 h-1 in methyl formate synthesis.
- Kroecher, Oliver,Koeppel, Rene A.,Baiker, Alfons
-
-
Read Online
- The new catalytic property of supported rhenium oxides for selective oxidation of methanol to methylal
-
A new catalytic property of supported rhenium oxides has been found for selective methanol oxidation to methylal; high performances for the selective catalytic oxidation are observed with V2O5-, ZrO2-, Fe2O3- and TiO2-supported Reoxide catalysts, which are characterized by pulse experiments, XRD and XPS.
- Yuan, Youzhu,Shido, Takafumi,Iwasawa, Yasuhiro
-
-
Read Online
- Ruthenium trichloride as a new catalyst for selective production of dimethoxymethane from liquid methanol with molecular oxygen as sole oxidant
-
Dimethoxymethane was first synthesized from methanol with a liquid phase intermittent process which only used molecular oxygen as the sole oxidant. RuCl3 was proved to be an efficient catalyst as it posses the ability of oxidizing methanol and Lewis acidic which promotes the oxidation of methanol to formaldehyde and then methanol condensed with formaldehyde to form dimethoxymethane at Lewis acid site.
- Li, Meilan,Long, Yan,Deng, Zhiyong,Zhang, Hua,Yang, Xiangui,Wang, Gongying
-
-
Read Online
- Novel anion exchange resin-based catalyst for liquid-phase methanol synthesis at 373-393 K
-
A thermo-stable anion exchange resin-Raney Cu system was found as the most effective solid catalyst for low-temperature liquid-phase methanol synthesis at 373 to 393 K under 5.0 MPa of syngas (2H2/CO). With the catalyst (20 mL of the resin and 2.0 g of Cu) suspended in methanol solution 72% of CO was converted to methanol (70%) and methyl formate (HCOOCH3) (30%) in 4 h.
- Aika, Ken-Ichi,Kobayashi, Hidenobu,Harada, Kenji,Inazu, Koji
-
-
Read Online
- Selective oxidation of dimethylether to formaldehyde on small molybdenum oxide domains
-
A study on the catalytic chemistry involved in the conversion of dimethyl ether (DME) to formaldehyde on active metal oxides was carried out. MoOx species dispersed as small domains on Al2O3, ZrO2, and SnO2 catalyzed the oxidative conversion of DME to formaldehyde with high primary selectivity (80-98% HCHO, CH3OH-free basis) at 500-550 K. The reaction proceeded via redox cycles utilizing lattice oxygen and turnover rates increased with the reducibility and size of MoOx domains. DME conversion rates and formaldehyde selectivities at 513 K were considerably higher than those previously observed on different catalysts at 620-880 K.
- Iglesia,Liu
-
-
Read Online
- Vapor-phase dehydrogenation of methanol to methyl formate in catalytic membrane reactor with Pd/SiO2/ceramic composite membrane
-
Vapor-phase dehydrogenation of methanol to methyl formate was investigated in the catalytic membrane reactor (CMR) with the Pd/SiO2/ceramic composite membrane prepared by an impregnation method. The studies show that the CMR has much better performance than the fixed-bed reactor, in which no methyl formate is detected under the similar reaction conditions. Copyright
- Guo, Yanglong,Lu, Guanzhong,Mo, Xunhua,Wang, Yunsong
-
-
Read Online
- Investigation of the interaction between Cu(acac)2 and NH4Y in the preparation of chlorine-free CuY catalysts for the oxidative carbonylation of methanol to a fuel additive
-
The high temperature anhydrous interaction between copper(ii) acetylacetonate Cu(acac)2 and NH4Y was investigated to prepare a chlorine-free CuY catalyst for the oxidative carbonylation of methanol to dimethyl carbonate. When a physical mixture of Cu(acac)2 and NH4Y is heated from ambient temperature to 230 °C, Cu(acac)2 firstly sublimates and then is adsorbed immediately onto the surface of the Y zeolite. Simultaneously the ion exchange between Cu(acac)2 and NH4Y occurs at about 174 °C. During the activation process from 230 to 500 °C, the exchanged Cu2+ is reduced to a Cu+ active center, and the adsorbed and unreacted Cu(acac)2 on the NH4Y surface decomposes to nano-CuO. For NaY zeolite, no solid state ion-exchange occurs between Cu(acac)2 and NaY during the heat treatment and only CuO exists on the Cu/NaY catalyst surface. While for HY zeolite, there is less ion-exchanged Cu+ in the supercages. The Cu/NaY catalyst has no catalytic activity and the Cu/HY catalyst exhibits lower activity than the Cu/NH4Y catalyst. Strong evidence is provided that during heat treatment, a solid state ion-exchange between Cu(acac)2 and NH4Y occurs and makes more of the Cu+ located in the supercages accessible to reactants.
- Wang, Yuchun,Zheng, Huayan,Li, Zhong,Xie, Kechang
-
p. 102323 - 102331
(2015)
-
Read Online
- Zirconia-supported MoOx catalysts for the selective oxidation of dimethyl ether to formaldehyde: Structure, redox properties, and reaction pathways
-
Dimethyl ether (DME) reacts to form formaldehyde with high selectivity at 500-600 K on MoOx-ZrO2 catalysts with a wide range of MoOx surface density (0.5-50.1 Mo/nm2) and local structure (monomers, oligomers, MoO3 crystallites, and ZrMo2O8). Reaction rates (per Mo-atom) increased markedly as MoOx surface density increased from 2.2 to 6.4 Mo/nm2 and two-dimensional polymolybdates and MoO3 clusters became the prevalent active species. The rate of incipient stoichiometric reduction of MoOx-ZrO2 samples in H2 also increased with increasing MoOx surface density, suggesting that catalytic turnovers involve redox cycles that become faster as the size and dimensionality of MoOx domains increase. DME reaction rates (per Mo-atom) decreased as MoOx surface densities increased above 6.4 Mo/nm2, as MoO3 and ZrMo2O8 clusters with increasingly inaccessible MoOx species form. On MoOx and ZrMo2O8, areal reaction rates reach a constant value at MoOx surface densities above 10 Mo/nm2, as the exposed surfaces become covered with the respective active species. ZrMo2O8 surfaces were more reducible in H2 than MoOx surfaces and showed higher areal reaction rates. Reaction rates were nearly independent of O2 pressure, but the reaction order in DME decreased from one at low pressures (60 kPa). DME reacts via primary pathways leading to HCHO, methyl formate, and COx, with rate constants k1, k2, and k3, respectively, and via secondary HCHO conversion to methylformate (k4) and COx (k5). Primary HCHO selectivities (and k1/(k2 + k3) ratios) increased with increasing MoOx surface density on MoOx-containing samples and reached values of 80-90% above 10 Mo/nm2. Kinetic ratios relevant to secondary HCHO reactions (k1/[(k4 + k5)CAO]; CAO inlet DME concentration) also increased with increasing MoOx surface density to values of a??0.1 and 0.8 on MoOx and ZrMo2O8 structures (at the constant inlet DME concentration CAO), respectively. Thus, increasing the coverage of ZrO2 surfaces with MoOx or ZrMo2O8 leads to more selective structures for HCHO synthesis from DME.
- Liu, Haichao,Cheung, Patricia,Iglesia, Enrique
-
-
Read Online
- On the methylation of 3-cyano-6-hydroxypyridine-2(1H)-ones
-
In order to prepare new heterocyclic derivatives as building block for compounds with potential biological activities, we were led to study the O- methylation of 3-cyano-6-hydroxypyridine-2(1H)-ones such as 1. This enabled us to develop a new two steps method to prepare the corresponding 2,6- dimethoxy derivative 5 in 80 % yield. It consisted first in heating 1 in trimethylorthoformate, with or without an acidic catalyst, which gave a mixture of the two mono-methoxy isomers, then a classical methylation of the second hydroxy moiety led almost exclusively to 5. In this paper we present this 'methylation' method and various unexpected results recorded when we attempted to extend it to related derivatives or to other heterocycle containing lactim-lactam functions. An intramolecular transetherification mechanism requiring the simultaneous transfer of a hydrogen and a methyl is suggested.
- Janin, Yves Louis,Chiki, Jaouad,Legraverend, Michel,Huel, Christiane,Bisagni, Emile
-
-
Read Online
- Ozone-activated nanoporous gold: A stable and storable material for catalytic oxidation
-
We report a new method for facile and reproducible activation of nanoporous gold (npAu) materials of different forms for the catalytic selective partial oxidation of alcohols under ambient pressure, steady flow conditions. This method, based on the surface cleaning of npAu ingots with ozone to remove carbon documented in ultrahigh vacuum conditions, produces active npAu catalysts from ingots, foils, and shells by flowing an ozone/dioxygen mixture over the catalyst at 150 °C, followed by a temperature ramp from 50 to 150 °C in a flowing stream of 10% methanol and 20% oxygen. With this treatment, all three materials (ingots, foils, and shells) can be reproducibly activated, despite potential carbonaceous poisons resulting from their synthesis, and are highly active for the selective oxidation of primary alcohols over prolonged periods of time. The npAu materials activated in this manner exhibit catalytic behavior substantially different from those activated under different conditions previously reported. Once activated in this manner, they can be stored and easily reactivated by flow of reactant gases at 150 °C for a few hours. They possess improved selectivity for the coupling of higher alcohols, such as 1-butanol, and are not active for carbon monoxide oxidation. This ozone-treated npAu is a functionally new catalytic material.
- Personick, Michelle L.,Zugic, Branko,Biener, Monika M.,Biener, Juergen,Madix, Robert J.,Friend, Cynthia M.
-
-
Read Online
- Preparation and evaluation of Cu-Mn/Ca-Zr catalyst for methyl formate synthesis from syngas
-
Cu-Mn/Ca-Zr catalysts were prepared by mechanical mixing, sol-gel and impregnation methods. The phase structure, surface morphology and the chemical states of catalysts were characterized by XRD, TEM, SEM and XPS. The basic property and reducibility of catalysts were investigated by CO2-TPD and H2-TPR techniques. Several types of basic sites with different basicity could be observed on the surface of catalysts. The sample prepared by impregnation method has the lowest reducibility, and the sample prepared by sol-gel method shows the highest reducibility. The catalytic performance was evaluated for the direct synthesis of methyl formate from syngas in a slurry phase. The catalyst prepared by mechanical mixing method shows the highest CO conversion of 14.2% and methyl formate selectivity of 83.4% among these catalysts, which could be attributed to the large amounts of strong basic sites and low reducibility of the catalyst.
- Zhao, Haijun,Lin, Minggui,Fang, Kegong,Zhou, Juan,Sun, Yuhan
-
-
Read Online
- Levulinic esters from the acid-catalysed reactions of sugars and alcohols as part of a bio-refinery
-
Polymeric humin formation greatly diminishes levulinic acid yields in acid treatment of C6 sugars in aqueous medium. Protecting reactive functional groups of sugars and reaction intermediates via acetalisation and etherification in methanol medium effectively suppresses humin formation and remarkably enhances the production of levulinic esters.
- Hu, Xun,Li, Chun-Zhu
-
-
Read Online
- CATALYTIC ACTIVITIES OF COPPERS IN THE VARIOUS OXIDATION STATES FOR THE DEHYDROGENATION OF METHANOL
-
The catalytic activities of coppers for the conversion of methanol are individually different by their oxidation states.Cu(II) ion and Cu(O) catalyze the dehydrogenation to form methyl formate and formaldehyde, respectively, while Cu(I) ion is inactive.
- Takagi, Katsuhiko,Morikawa, Yutaka,Ikawa, Tsuneo
-
-
Read Online
- ANIONIC GROUP 6B METAL CARBONYLS AS HOMOGENEOUS CATALYSTS FOR CARBON DIOXIDE/HYDROGEN ACTIVATION. THE PRODUCTION OF ALKYL FORMATES.
-
The production of alkyl formates from the hydrocondensation of carbon dioxide in alcohols utilizing anionic group 6B carbonyl hydrides as catalysts is reported. HM(CO)//5** minus (M equals Cr, W; derived from mu -H left bracket M//2(CO)//1//0 right bracket ** minus ) and their products of carbon dioxide insertion, HCO//2M(CO)//5** minus , have been found to be effective catalysts for the hydrogenation of CO//2 in alcohols under rather mild conditions (loading pressures of CO//2 and H//2, 250 psi each, and 125 degree C) to provide alkyl formates. The only metal carbonyl species detected in solution via infrared spectroscopy, both at the end of a catalytic period and during catalysis, were M(CO)//6 and HCO//2M(CO)//5** minus .
- Darensbourg,Ovalles
-
-
Read Online
- A Promoting Effect of Phosphorus-Addition to Cu/SiO2 on Selective Synthesis of Formaldehyde by Dehydrogenation of Methanol
-
Copper supported on SiO2, which was prepared from Cu(OCOCH3)3 and to which P was added, was a selective catalyst (80-85 percent at about 50 percent conversion) for the formation of HCHO by the dehydrogenation of CH3OH at 500 deg C.Among various additives such as P, B, K, Li, Mo, and Zn, the addition of P to the Cu/SiO2 significantly enhanced the rate for the formation of HCHO with an increase in the selectivity.
- Yamamoto, Takeshi,Shimoda, Akihide,Okuhara, Toshio,Misono, Makoto
-
-
Read Online
- Photocatalytic cross-coupling of methanol and formaldehyde on a rutile TiO2(110) surface
-
The photocatalytic oxidation of methanol on a rutile TiO2(110) surface was studied by means of thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). The combined TDS and XPS results unambiguously identify methyl formate as the product in addition to formaldehyde. By monitoring the evolution of various surface species during the photocatalytic oxidation of methanol on TiO2(110), XPS results give direct spectroscopic evidence for the formation of methyl formate as the product of photocatalytic cross-coupling of chemisorbed formaldehyde with chemisorbed methoxy species and clearly demonstrate that the photocatalytic dissociation of chemisorbed methanol to methoxy species occurs and contributes to the photocatalytic oxidation of methanol. These results not only greatly broaden and deepen the fundamental understanding of photochemistry of methanol on the TiO2 surface but also demonstrate a novel green and benign photocatalytic route for the synthesis of esters directly from alcohols or from alcohols and aldehydes.
- Yuan, Qing,Wu, Zongfang,Jin, Yuekang,Xu, Lingshun,Xiong, Feng,Ma, Yunsheng,Huang, Weixin
-
-
Read Online
- Low temperature oxidation of methanol to methyl formate over Pd nanoparticles supported on γ-Fe2O3
-
Pd nanoparticles supported on γ-Fe2O3 (2 wt.%) were synthesized using the water-in-oil microemulsion method (using hydrazine as a reductant agent). Materials were characterized by N2-BET at low temperature, XRD, XPS, Raman, and FTIR and tested in the gas phase reaction of oxidation of methanol. The direct formation of methyl formate (MF) from methanol was observed. Supported palladium catalysts produced methyl formate at low temperature (+2/Fe+3 ratio (2:1, 1:1, 1:2) used for the preparation of the supports. Methyl formate is already formed at 50 °C with the maximum at about 80 °C. At higher temperature, methyl formate is no longer formed and the oxidation to CO2 and CO occurs. Raman studies indicated the changes in the structure of the Fe2O3 support in the case of the 1:2 sample after chemical reduction with hydrazine.
- Wojcieszak,Ghazzal,Gaigneaux,Ruiz
-
-
Read Online
- A comparative study on the effect of Zn addition to Cu/Ce and Cu/Ce-Al catalysts in the steam reforming of methanol
-
The performances of different catalysts xCu10Ce and xCu10Ce10Al (with x = 1, 3 and 5) in the steam reforming of methanol reaction were studied with and without the presence of zinc. The reaction was investigated at 350°C with a Gas Hourly Space Velocity o
- Mrad, Mary,Hammoud, Dima,Gennequin, Cédric,Abouka?s, Antoine,Abi-Aad, Edmond
-
-
Read Online
- Photocatalytically reducing CO2 to methyl formate in methanol over ag loaded SrTiO3 nanocrystal catalysts
-
Ag-SrTiO3 nanocrystal photocatalysts were prepared by hydrothermal synthesis method for reducing CO2 to methyl formate (MF) in methanol via ultraviolet irradiation. CO2 was reduced to MF by electrons on conduction band of the photocatalyst. In order to obtain a high rate of MF evolution, we researched and optimized the preparation procedure of Ag-SrTiO3 by changing the Ag dosage, hydrothermal temperature and time. The as synthesized photocatalystswere characterized with X-ray diffraction, UV-Vis absorption spectra, transmission electron microscope, N 2 sorption analysis at 77 K and activity evaluation. A catalyst of 7 wt% Ag on SrTiO3 with hydrothermal synthesis at 150 °C and 22 h was found to exhibit the highest photocatalytic activity inMF formation rate of 3,006 μmol/(h g cat), which was more remarkable than that of pristine SrTiO3.
- Sui, Dandan,Yin, Xiaohong,Dong, Hongzhi,Jiang, Wanlin,Qin, Shiyue,Chen, Jingshuai
-
-
Read Online
- The direct synthesis of dimethyl carbonate by the oxicarbonylation of methanol over Cu supported on carbon nanotube
-
The activity of Cu/MWCNT and Cu-Ni/MWCNT catalysts was investigated in the synthesis of dimethyl carbonate (DMC) by oxidative carbonylation of methanol. The catalysts were prepared via conventional incipient wetness impregnation technique. The samples were characterized by X-ray photoelectron spectroscopy (XPS), and DRIFT. The reaction was carried out in a continuous flow system at atmospheric pressure at 393 K. The main products were methyl formate (MF), DMC and CO2. The methanol conversion on Cu/MWCNT achieved a steady state value after 2 h, but on Cu-Ni/MWCNT the conversion decreased continuously. The DMC selectivity was more than 30% and the yield was 1.2% on Cu/MWCNT. Based on the XPS data we can establish that copper reduced to its metallic form during reduction but oxidized in the reaction mixture, and is mostly in the Cu + state, with some Cu2+ also present on the surface at the beginning of the reaction though its ratio decreased in time. We assume that the DMC formation rate depends on the surface concentration of oxidized Cu. Based upon the FTIR data adsorbed DMC is present on the surface of the Cu/MWCNT catalyst during the catalytic reaction but on Cu-Ni/MWCNT sample only methyl formate was detected in the gas phase.
- Merza,László,Oszkó,Pótári,Baán,Erdohelyi
-
-
Read Online
- Electrochemical activation of Au nanoparticles for the selective partial oxidation of methanol
-
An electrochemical catalyst based on Au nanoparticles dispersed in an yttria-stabilized zirconia (YSZ) matrix was prepared by reactive cosputtering of zirconium-yttrium and Au targets on a K-βAl2O3 solid electrolyte. The Au/YSZ catalyst film deposited on K-βAl2O 3 was found to be active in the partial oxidation of methanol with a high selectivity toward methyl formate. This configuration allowed to electrochemically promote a highly dispersed Au catalyst by K+ ions and allowed to decrease the amount of metal used in the solid electrolyte cell. The back-spillover of K+ ions sharply increased the H2 and HCOOCH3 production rates up to more than 9 and 5 times, respectively. A number of experiments confirmed that the observed electro-promotional effect did not depend on the rate of K+ supply nor on the operation mode (galvanostatic or potentiostatic) and only depended on the promoter coverage (total applied charge). The stability of the Au-YSZ catalyst film under the explored conditions was also verified.
- Gonzalez-Cobos,Horwat,Ghanbaja,Valverde,De Lucas-Consuegra
-
-
Read Online
- Low-temperature CO2 hydrogenation to liquid products via a heterogeneous cascade catalytic system
-
Research described in this paper targeted a cascade system for the hydrogenation of CO2 to methanol via formic acid and/or formate intermediates, a reaction sequence that has been accomplished previously using homogeneous catalysts. On the basis of results for the hydrogenation of CO2, formic acid, and ethyl formate over a series of Cu- and Mo2C-based catalysts, we selected a Cu chromite catalyst for CO2 hydrogenation to the formate and a Cu/Mo2C catalyst to convert the formate to methanol. These catalysts worked cooperatively in the presence of ethanol, yielding a methanol turnover frequency of 4.7 × 10-4 s-1 at 135 °C, 10 bar of CO2, and 30 bar of H2 in 1,4-dioxane. The performance for this Cu chromite:Cu/Mo2C cascade system surpassed the additive production of the individual catalysts by 60%. The results also allowed an investigation of the reaction pathways. The hydrogenation of CO2 to formic acid appeared to be the rate-limiting step for most of the catalysts. This is not surprising given the thermodynamics for this reaction. Finally, the hydrogenation of CO2 to dimethyl ether was also demonstrated using a system consisting of the Cu/Mo2C catalyst to produce methanol from CO2 and HZSM-5 to produce dimethyl ether from methanol. The systems described in this paper are, to our knowledge, the first demonstrating cascade CO2 hydrogenation via heterogeneous catalysts.
- Chen, Yuan,Choi, Saemin,Thompson, Levi T.
-
-
Read Online
- Photocatalytic partial oxidation of methanol to methyl formate under visible light irradiation on Bi-doped TiO2: Via tuning band structure and surface hydroxyls
-
Preparing visible light responsive catalysts for partial oxidation of methanol to methyl formate is a challenging issue. This work addresses the synthesis, characterization and theoretical calculation of Bi doped TiO2 catalysts as well as their photocatalytic performance and reaction mechanism for MF synthesis from methanol. The catalysts were prepared by a simple wet chemical method. The results of the characterization and theoretical calculation evidenced that bismuth was intercalated in the lattice of anatase by the substitution of titanium. Impurity levels were formed in the valence band, conduction band and between the two bands. The Bi 6s and 5p orbitals contributed to the formation of the impurity levels. The photo-excited electrons transited from the valence band via impurity levels, formed by Bi 6s orbitals, to the conduction band. The doping of Bi enhanced surface hydroxyls, reduced the band gaps and raised the valence band edges (VBE) of the Bi doped catalyst. The Bi doped catalysts were visible light responsive due to the reduced band gap. The surface hydroxyls were beneficial to the methanol conversion, and the rise of the VBE enhanced the redox potential of the photogenerated holes. Only moderate redox potentials and sufficient surface hydroxyls could lead to high methanol conversion and MF selectivity. This study is of great significance to the development of the photocatalytic synthesis theory and provides a green route for MF synthesis from methanol. This journal is
- Gao, Guanjun,Lei, Yanqiu,Ma, Yue,Su, Haiquan,Yan, Zhe,Yang, Xuzhuang,Zhang, Bingbing,Zhang, Yanbing
-
-
Read Online
- Hydrogenation of carbon dioxide in the presence of rhodium catalysts
-
The results of CO2 hydrogenation in the presence of the Wilkinson complexes, viz., RhCl3 and acacRh(CO)2, at room temperature and excess PPh3 are presented. The influence of different ions on the catalytic properties of the Rh complexes was studied. Methanol and methyl formate are formed along with formic acid in the presence of an inorganic salt. Ions that are the most active in the formation of formic acid are the least active in methanol formation.
- Kolesnichenko,Ezhova,Kremleva,Slivinskii
-
-
Read Online
- Methanol oxidation on VSiBEA zeolites: Influence of v content on the catalytic properties
-
This study deals with the influence of V content on the catalytic properties of VxSiBEA zeolites in the oxidation of methanol. The samples are prepared following a postsynthesis method reported earlier (S. Dzwigaj, M.J. Peltre, P. Massiani, A. Davidson, M. Che, T. Sen, S. Sivasanker, Chem. Commun. (1998) 87). The incorporation of isolated mononuclear V(V) into the framework of SiBEA is evidenced by XRD, FTIR, diffuse reflectance UV-vis and NMR. It is found that, for low V content, V(V) ions are in pseudo-tetrahedral coordination only, either in nonhydroxylated (SiO)3VO or hydroxylated (SiO)2(OH)VO species in framework position. For higher V content, additional species appear in extraframework position with vanadium in octahedral coordination. FTIR investigations of pyridine adsorption show that strong Bronsted and Lewis acidic centres are present in SiBEA leading to dimethyl ether only, in methanol oxidation. Upon incorporation of vanadium into the BEA framework, Lewis acidic (V5+) and basic (O2-) centres are generated with simultaneous appearance of partial oxidation products mainly, whose total concentration increases with vanadium content. These results suggest that those centres are responsible for the oxidation activity of VxSiBEA zeolites. The selectivity toward formaldehyde increases with the amount of vanadium present as pseudo-tetrahedral hydroxylated (SiO) 2(HO)VO species. This selectivity is suggested to be related to the moderate nucleophilicity of the basic vanadyl oxygen (VO) of (SiO) 2(HO)VO species.
- Trejda, MacIej,Ziolek, Maria,Millot, Yannick,Chalupka, Karolina,Che, Michel,Dzwigaj, Stanislaw
-
-
Read Online
- Promotional effect of potassium salt in low-temperature formate and methanol synthesis from CO/CO2/H2 on copper catalyst
-
Alkyl formates can be formed from CO2-containing syngas with C1-C4 alkyl alcohol solvents in the presence of potassium carbonate, which changed to potassium formate as catalyst. The formates can be in situ hydrogenolysized further to produce methanol effectively over manganese oxide or magnesia-supported copper catalysts. These homogeneous and heterogeneous catalysts constitute a novel system for methanol synthesis from CO/CO2/H2 even at 443 K. Copyright
- Zhao, Tian-Sheng,Yoneyama, Yoshiharu,Fujimoto, Kaoru,Yamane, Nodyuki,Fujimoto, Kenichiro,Tsubaki, Noritatsu
-
-
Read Online
- Highly active CuZn/SBA-15 catalyst for methanol dehydrogenation to methyl formate: Influence of ZnO promoter
-
Stable and efficient Cu/SBA-15 and xCuZn/SBA-15 (x = 5, 10 and 15) in methanol dehydrogenation to methyl formate (MF) are prepared through a double-solvent impregnation (DI) method. Among all catalysts, 10CuZn/SBA-15 shows the highest catalytic performance with selectivity to MF about 88.1 % and methanol conversion of 31.1 %, which is attributed to the well-dispersed Cu particles and high ratio of Cu°/(Cu° + Cu+). The proper amount of ZnO could improve dispersion of Cu because of its geometrical spacer, inhibiting growth of Cu particle, and the best dispersion is achieved in 10CuZn/SBA-15. Furthermore, the Cu°/(Cu° + Cu+) ratio is greatly promoted with the assistance of ZnO, attributed to Cu-ZnO interaction, which reaches maxima of 53.3 % at a Cu/Zn mole ratio of 10. Specially, the optimized catalyst shows evident suitability at high temperature for methanol dehydrogenation reactions along with high level of conversion and selectivity for 100 h. Overall, our findings reveal that modification by the appropriate amount of ZnO in Cu-based catalyst has a positive impact on obtaining MF for the methanol dehydrogenation.
- Wang, Na,Quan, Yanhong,Zhao, Jinxian,Li, Haixia,Ren, Jun
-
-
Read Online
- Catalytic oxidation of alcohol via nickel phosphine complexes with pendant amines
-
Nickel complexes were prepared with diphosphine ligands that contain pendant amines, and these complexes catalytically oxidize primary and secondary alcohols to their respective aldehydes and ketones. Kinetic and mechanistic studies of these prospective electrocatalysts were performed to understand what influences the catalytic activity. For the oxidation of diphenylmethanol, the catalytic rates were determined to be dependent on the concentration of both the catalyst and the alcohol and independent of the concentration of base and oxidant. The incorporation of pendant amines to the phosphine ligand results in substantial increases in the rate of alcohol oxidation with more electron-donating substituents on the pendant amine exhibiting the fastest rates. (Chemical Equation Presented).
- Weiss, Charles J.,Das, Parthapratim,Miller, Deanna L.,Helm, Monte L.,Appel, Aaron M.
-
-
Read Online
- Broensted Basicity of Atomic Oxygen on the Au(110) Surface: Reactions with Methanol, Acetylene, Water, and Ethylene
-
The adsorption and reactions of methanol, acetylene, water, and ethylene were investigated on clean and oxidized Au(110) surfaces by temperature-programmed reaction spectroscopy.All of these molecules are only weakly and molecularly adsorbed on the clean Au(110) surface.Methanol, acetylene, and water, however, react with the oxidized surface.Methanol, activated by 0.25 monolayer of oxygen adatoms, reacts to form water, methyl formate, hydrogen, and carbon dioxide.A stable methoxy intermediate is identified in these reactions.Acetylene reacts to form water and carbon dioxide, and water is more strongly bonded to the Au(110) surface in the presence of oxygen adatoms.Ethylene is the only one of these molecules which does not react with oxygen adatoms on Au(110).This pattern of reactivity parallels that associated with the acidity of these molecules as measured in the gas phase which has been observed on Cu(110) and Ag(110) surfaces.These results complete the studies necessary to demonstrate the Broensted base character of oxygen adatoms on all of the group 1B metals.
- Outka, Duane A.,Madix, R. J.
-
-
Read Online
- Oxidation of methanol to methyl formate over supported Pd nanoparticles: Insights into the reaction mechanism at low temperature
-
Pd nanoparticles supported on TiO2 and SiO2 (2 wt.%) were synthesized by the water-in-oil microemulsion method. The materials were characterized by standard physico-chemical methods (XRD, ICP, TEM, BET, XPS) and DRIFT in operando mode and tested in the gas-phase reaction of methanol oxidation. The direct formation of methyl formate (MF) from methanol was observed. Supported palladium catalysts produced methyl formate at low temperature (2 occurred. The DRIFT-operando study confirmed that methanol is adsorbed mainly in two forms, the undissociated gaseous methanol (via H bond) and dissociatively adsorbed methoxy species (CH3O-) on the surface. Methyl formate is formed already at RT with the maximum at about 80 °C. The mechanism of the formation of methyl formate from methanol at low temperature is discussed. the Partner Organisations 2014.
- Wojcieszak,Karelovic,Gaigneaux,Ruiz
-
-
Read Online
- Comparative study on the photocatalytic decomposition of methanol on TiO2 modified by N and promoted by metals
-
The photo-induced vapor-phase reaction of methanol was investigated on Pt metals deposited on pure and N-doped TiO2. Infrared spectroscopic measurements revealed that illumination of the CH3OH-TiO2 and CH3OH-M/TiO2 systems led to the conversion of adsorbed methoxy species into adsorbed formate. In the case of metal-promoted TiO 2 catalysts CO bonded to the metals was also detected. Pure titania exhibited very little photoactivity, its efficiency, however, increased with the narrowing of its bandgap by N-doping, a feature attributed to the prevention of electron-hole recombination. Deposition of Pt metals on pure and N-doped TiO2 dramatically enhanced the extent of photoreaction of methanol even in visible light: hydrogen and methyl formate with selectivities of 83-90% were the major products. The most active metal was Pt followed by Pd, Ir, Rh, and Ru. The effect of metal was explained by a better separation of charge carriers induced by illumination and by enhanced electronic interaction between metal nanoparticles and TiO2.
- Halasi, Gyula,Schubert, Gabor,Solymosi, Frigyes
-
-
Read Online
- Simplified DEMS set up for electrocatalytic studies of porous PtRu alloys
-
A simplified experimental apparatus for Differential Electrochemical Mass Spectrometry (DEMS) was constructed having only one turbomolecular pump and a modified gas inlet system. The setup allows the determination of the activity of porous PtRu electrodes for the electro-oxidation of small organic molecules. Various PtRu alloys with defined composition can be electrodeposited onto porous gold substrates. First results on the electrooxidation of methanol in acid solution were presented.
- Ianniello,Schmidt
-
-
Read Online
- Alcohol-Activated Vanadium-Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with 51V-NMR and EPR Spectroscopy
-
Alcoholic solvents, especially methanol, show an activating affect for heteropolyacids in homogenously catalysed glucose transformation reactions. In detail, they manipulate the polyoxometalate-based catalyst in a way that thermodynamically favoured total oxidation to CO2 can be completely supressed. This allows a nearly 100 % carbon efficiency in the transformation reaction of glucose to methyl formate in methanolic solution at mild reaction conditions of 90 °C and 20 bar oxygen pressure. By using powerful spectroscopic tools like 51V-NMR and continuous wave EPR we could unambiguously prove that the vanadate-methanol-complex[VO(OMe)3]n is responsible for the selectivity shift in methanolic solution compared to the aqueous reference system.
- Wesinger, Stefanie,Mendt, Matthias,Albert, Jakob
-
-
Read Online
- CuO - Activated carbon catalysts for methanol decomposition to hydrogen and carbon monoxide
-
A comparison of the abilities of CuO - activated carbon catalysts, prepared by different copper precursors and preparation techniques, in the methanol decomposition reaction to carbon monoxide and hydrogen, was undertaken. Higher catalytic activity and stability are found for the catalysts obtained from an ammonia solution of copper carbonate. The nature of the catalytic active complex in the samples is also discussed.
- Tsoncheva, Tanya,Nickolov, Radostin,Vankova, Svetoslava,Mehandjiev, Dimitar
-
-
Read Online
- Effective Dawson type polyoxometallate catalysts for methanol oxidation
-
Dawson type polyoxometallates K6P2Mo xW18-xO62 (x = 0, 5, 6) and α1 and α2-K7P2Mo5VW12O62 were prepared and characterized by BET, IR, UV-vis and 31P NMR spectroscopies and thermal analysis (TG and DTA) and tested in methanol oxidation at 260°C in the presence of molecular oxygen. The Dawson compounds were found to be active in this reaction and the product distribution (formaldehyde, methyl formate, dimethylether, dimethoxymethane) depends on the polyanion composition and on the framework symmetry. α-K6P 2W18O62 exhibits an excellent catalytic performance with ca. 27% of methanol conversion and 98% of dimethylether selectivity. α1-K7P2Mo5VW 12O62 and α2-K7P2Mo 5VW12O62 show a similar activity (17-19% of conversion) with 49% of methyl formate selectivity and 41% of formaldehyde selectivity respectively. α-K6P2Mo6W 12O62 is the most oxidizing catalyst and the most selective toward the methyl formate (ca. 53%).
- Dermeche, Leila,Salhi, Nassima,Hocine, Smain,Thouvenot, René,Rabia, Chérifa
-
-
Read Online
- Selective oxidation of methanol to methyl formate on catalysts of Au-Ag alloy nanoparticles supported on titania under UV irradiation
-
We find that the Au-Ag alloy nanoparticles supported on titania exhibit superior methanol conversion and methyl formate selectivity for selective oxidation of methanol by low partial pressure oxygen in air under UV irradiation in the 15°C-45°C temperature range, with the highest methanol conversion above 90% and the highest selectivity towards methyl formate above 85%. The only by-product definitely detected is CO2. The superior photocatalytic performance of the catalyst is closely related to the special structure of the catalyst and the electronic properties of the alloy, which reduce the recombination of the photo-excited electron-hole pairs by transferring the photo-excited electrons in time from the conduction band of titania to the alloy on the one hand, and elevate the negative charge level of the alloy surface by the spd hybridization, the formation of Schottky barriers, the electron transfer from the conduction band of titania to the metal as well as the interband and intraband electron transitions under UV irradiation on the other hand. The photo-generated holes are responsible for the oxidation from methanol to coordinated methoxy, from coordinated methoxy to coordinated formaldehyde and finally to carbon dioxide. The methyl formate selectivity is dependent on the density of the surface methoxy. To enhance the efficiency of electron-hole separation is beneficial to the formation of the coordinated methoxy and coordinated formaldehyde and thus the selectivity to methyl formate. The negative charges on the surface of the metal are responsible for the dissociation of oxygen, which is the rate-determining step in the reaction. The dissociative oxygen repels the water molecules formed from the surface hydroxyls and refills the oxygen vacancies on the surface of titania. The surface oxygen is the acceptor of the hydrogen dissociated from methanol and/or methoxy and thus is beneficial for the formation of the coordinated methoxy and coordinated formaldehyde. The oxygen partial pressure remarkably influences the methanol conversion and the methyl formate selectivity. The light intensity has a remarkable impact on the methanol conversion but not on the methyl formate selectivity. These findings provide useful insight into the design of catalysts for selective oxidation of methanol to methyl formate in a more green way. This journal is the Partner Organisations 2014.
- Han, Chenhui,Yang, Xuzhuang,Gao, Guanjun,Wang, Jie,Lu, Huailiang,Liu, Jie,Tong, Min,Liang, Xiaoyuan
-
-
Read Online
- RuO2 clusters within LTA zeolite cages: Consequences of encapsulation on catalytic reactivity and selectivity
-
(Figure Presented) Trapped! The title system (ca. 1 nm diameter; left) catalyzes methanol oxidation with higher turnover rates than clusters on SiO2 supports. Spatial constraints lead to the preferential oxidation of methanol over larger alcohols. Restricted access to active sites also protects encapsulated Ru clusters (right) against inhibition of ethene hydrogenation by organosulfur compounds.
- Zhan, Bi-Zeng,Iglesia, Enrique
-
-
Read Online
- Vapour-Phase Carbonylation of Methanol over Tin Catalyst Supported on Active Carbon
-
A Tin-active carbon showed a catalytic activity for the vapour phase carbonylation of methanol under pressurized conditions in the presence of methyl iodide promoter.
- Omata, Kohji,Yagita, Hiroshi,Shikada, Tsutomu,Fujimoto, Kaoru,Tominaga, Hiro-o
-
-
Read Online
- Preparation of MIL-88B(Fex,Co1?x) catalysts and their application in one-step liquid-phase methanol oxidation to methyl formate using H2O2
-
The selective oxidation of methanol to methyl formate is one of the most attractive processes to obtain value-added methanol-downstream products. The development of highly efficient and stable catalysts is critical for this transformation. In this study, a series of MIL-88B(Fex,Co1–x) bimetallic catalysts with different Fe/Co molar ratios were prepared through a one-pot hydrothermal method. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption, and inductively coupled plasma-mass spectrometry characterization were performed to elucidate the structure of the catalysts. The activity of the catalysts were assessed in the one-step oxidation of methanol to methyl formate with H2O2 in a liquid-phase batch reactor. The results show that the MIL-88B(Fex,Co1–x) catalysts exhibit uniform needle-like morphologies with an average length and width of 400–600 nm and 100–150 nm, respectively. Co2+ is incorporated into the framework by partially replacing Fe3+ in MIL-88B. Moreover, the catalyst efficiently promoted the conversion of methanol to methyl formate. When MIL-88B(Fe0.7,Co0.3) catalyst was used with a molar ratio of H2O2 to methanol of 0.5 at 80 °C for 60 min, 34.8% methanol conversion was achieved, and the selectivity toward methyl formate was 67.6%. The catalysts also showed great stability with a steady conversion and selectivity even after four cycles. The preliminary oxidation mechanism was also studied. It was determined that H2O2 is first adsorbed on the Fe3+ sites and subsequently activates these sites. Methanol is adsorbed by the O atoms of the framework through hydrogen bonding and is gradually oxidized to formic acid. Subsequently, formic acid reacts with the residual methanol at the Fe3+ and Co2+ Lewis acid sites to form methyl formate.
- Cao, Qiyan,Ji, Shengfu,Liu, Jianfang,Ran, Zhenzhen
-
p. 2254 - 2264
(2021/09/20)
-
- Methanol Dehydrogenation to Methyl Formate Catalyzed by Cu/SiO2 Catalysts: Impact of Precipitation Procedure and Calcination Temperature
-
Considering three options for the synthesis of a catalyst by the precipitation method, the Cu/SiO2 catalysts prepared by changing the precipitation procedure and calcination temperature for the dehydrogenation of methanol was studied. When the CuO/SiO2 catalyst precursors were prepared through the addition of a copper nitrate aqueous solution into an ammonia aqueous solution (reverse precipitation) and co-current flow addition of both aqueous solutions, after reduction with gaseous hydrogen, small-sized metallic copper nanocrystallites were formed in the reduced Cu/SiO2 catalysts as compared to those prepared by the addition of an ammonia aqueous solution into a copper nitrate aqueous solution (direct precipitation). The reduced Cu/SiO2 catalysts prepared by the reverse precipitation method with relatively lower acidity and basicity emonstrated higher catalytic activity for the synthesis of methyl formate in methanol dehydrogenation. The reduced Cu/SiO2 catalysts prepared by the calcination at a lower temperature showed higher catalytic activity for the formation of methyl formate. The surface metallic Cu0 and Cu+ species catalyzed the methanol dehydrogenation to methyl formate while the surface Cu+ cations enhanced the decomposition of the resultant methyl formate to CO and H2.
- Jia, X. Y.,Wang, A. L.,Ye, C. L.,Yin, H. B.
-
p. 1302 - 1312
(2021/12/29)
-
- CATALYSTS FOR SELECTIVE OXIDATION OF METHANOL TO DIMETHOXYMETHANE AND RELATED METHODS
-
Embodiments include catalyst compositions and methods of synthesizing catalyst compositions for the selective oxidation of methanol to dimethoxymethane, as well as methods of selective oxidation of methanol to dimethoxymethane using catalyst compositions. The catalyst composition can comprise vanadium oxide and a mixed metal oxide, wherein the vanadium oxide is supported on the mixed metal oxide and wherein the mixed metal oxide includes a redox component and an acid component. The method of selective oxidation of methanol to dimethoxymethane can comprise at least the following step: contacting methanol with a catalyst composition in the presence of an oxidizing agent to produce dimethoxymethane.
- -
-
Paragraph 0074-0078
(2021/10/02)
-
- The facet effect of ceria nanoparticles on platinum dispersion and catalytic activity of methanol partial oxidation
-
The effect of platinum-supported nano-shaped ceria catalysts on methanol partial oxidation and methyl formate product selectivity has been investigated. A Pt-supported CeO2nanocube catalyst had a higher turnover frequency than nanosphere catalysts; however, nanosphere catalysts showed higher selectivity towards methyl formate. The observed ceria shape effect in catalysis was associated with the shape-dependent Pt dispersion and its oxidation states. Furthermore,in situstudies revealed that the reduced platinum and mono-dentate methoxy group were responsible for the higher turnover frequency.
- Choi, Hanseul,Choi, Minkee,Kim, Daeho,Park, Jeong Young,Reddy, Kasala Prabhakar,Ryoo, Ryong
-
supporting information
p. 7382 - 7385
(2021/08/03)
-
- Method for preparing formate by using nitromethane process byproduct formic acid
-
The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing formate by using a nitromethane process byproduct formic acid. The method comprises the following steps: adding alcohol into a nitromethane hydrolysis reaction solution to carry out esterification reaction, distilling and rectifying to obtain the formate, wherein the nitromethane hydrolysis reaction liquid contains formic acid and hydrochloric acid. The method solves the problems that in the prior art, formic acid is not easy to remove, and the added value of the byproduct calcium formate is low, and the byproduct formic acid can be fully recycled by adopting the esterification reaction of the low-carbon alcohol and the byproduct formic acid; the used low-carbon alcohol is ethanol or methanol, and the esterification product is low in boiling point and easy to separate; and the produced methyl formate and ethyl formate are high in added value and wide in application.
- -
-
Paragraph 0039-0046
(2021/07/08)
-
- Reaction Network Analysis of the Ruthenium-Catalyzed Reduction of Carbon Dioxide to Dimethoxymethane
-
Due to the growing interest in dimethoxymethane (DMM) as formaldehyde synthon and fuel additive, new and more efficient routes toward the formaldehyde analog are being investigated. One approach is the reductive transformation of carbon dioxide using a ruthenium phosphine catalyst and a Lewis acid additive in methanol. In the present work, we investigated the underlying reaction network, consisting of several intermediates, equilibria and side products, through in situ IR spectroscopy. We determined rate constants and activation parameters for the hydrogenation steps. Their temperature-dependent differences can be used to influence the product selectivity in this catalysis. To favor DMM formation, the acetalization equilibrium and especially the amount of water formed were identified as promising optimization opportunities. Simulation of concentration profiles on the basis of the proposed kinetic model enables the prediction of experimental product distributions for various reaction parameters, demonstrating the power of reaction network analysis for process optimization.
- Leopold, Max,Siebert, Max,Siegle, Alexander F.,Trapp, Oliver
-
p. 2807 - 2814
(2021/05/27)
-
- Reaction Mechanism of Pd-Catalyzed “CO-Free” Carbonylation Reaction Uncovered by In Situ Spectroscopy: The Formyl Mechanism
-
“CO-free” carbonylation reactions, where synthesis gas (CO/H2) is substituted by C1 surrogate molecules like formaldehyde or formic acid, have received widespread attention in homogeneous catalysis lately. Although a broad range of organics is available via this method, still relatively little is known about the precise reaction mechanism. In this work, we used in situ nuclear magnetic resonance (NMR) spectroscopy to unravel the mechanism of the alkoxycarbonylation of alkenes using different surrogate molecules. In contrast to previous hypotheses no carbon monoxide could be found during the reaction. Instead the reaction proceeds via the C?H activation of in situ generated methyl formate. On the basis of quantitative NMR experiments, a kinetic model involving all major intermediates is built which enables the knowledge-driven optimization of the reaction. Finally, a new reaction mechanism is proposed on the basis of in situ observed Pd-hydride, Pd-formyl and Pd-acyl species.
- Geitner, Robert,Gurinov, Andrei,Huang, Tianbai,Kupfer, Stephan,Gr?fe, Stefanie,Weckhuysen, Bert M.
-
supporting information
p. 3422 - 3427
(2020/12/15)
-
- Ni-MoOx bifunctional catalyst on SiO2 for vapor halide-free methanol carbonylation: Insight into synergistic catalysis between Ni and MoOx
-
A promising Ni-MoOx bifunctional catalyst for halide-free methanol carbonylation is developed by H2-reduction of NiO-MoO3/SiO2 obtained via facile impregnation method. Catalyst performance is strongly dependent on the calcination/reduction temperature. Over the preferable NiMo-350-600/SiO2 catalyst obtained by calcining at 350 °C and subsequently reducing at 600 °C, a methanol conversion of 4.2 % and acetyls space-time yield of 1.37 mol kgcat?1 h?1 are achieved with 22.1 % selectivity to acetyls at 290 °C and 3 MPa. Co-existence of Ni0 and MoOx (especially MoO2) markedly decreases formation of dimethyl ether (DME) and reversely increases acetyls formation, in nature, due to the catalyst acidity modulation and the partial electron transfer from Ni0 to MoOx that tunes the CO adsorption strength on Ni0 sites. MoO3 and NiMoO4 are both favorable for formation of acetyls and DME whereas the latter mainly accounts for DME formation. MoNi4 alone favors methyl formate formation while together with MoO2 enhancing DME production.
- Liu, Ye,Lu, Yong,Nie, Qiang,Shen, Mengchen,Zhao, Guofeng
-
-
- Photolytic Activation of Late-Transition-Metal-Carbon Bonds and Their Reactivity toward Oxygen
-
The photolytic activation of palladium(II) and platinum(II) complexes [M(BPI)(R)] (R = alkyl, aryl) featuring the 1,3-bis(2-pyridylimino)isoindole (BPI) ligand has been investigated in various solvents. In the absence of oxygen, the formation of chloro complexes [M(BPI)Cl] is observed in chlorinated solvents, most likely due to the photolytic degradation of the solvent and formation of HCl. The reactivity of the complexes toward oxygen has been studied both experimentally and computationally. Excitation by UV irradiation (365 nm) of the metal complexes [Pt(BPI)Me] and [Pd(BPI)Me] leads to distortion of the square-planar coordination geometry in the excited triplet state and a change in the electronic structure of the complexes that allows the interaction with oxygen. TD-DFT computational studies suggest that, in the case of palladium, the Pd(III) superoxide intermediate [Pd(BPI)(κ1-O2)Me] is formed and, in the case of platinum, the Pt(IV) peroxide intermediate [Pt(BPI)(κ2-O2)Me]. For alkyl complexes where metal-carbon bonds are sufficiently weak, the photoactivation leads to the insertion of oxygen into the metal-carbon bond to generate alkylperoxo complexes: for example [Pd(BPI)OOMe], which has been isolated and structurally characterized. For stronger M-C(aryl) bonds, the reaction of [Pt(BPI)Ph] with O2 and light results in a Pt(IV) complex, tentatively assigned as the peroxo complex [Pt(BPI)(κ2-O2)Ph], which in chlorinated solvents reacts further to give [Pt(BPI)Cl2Ph], which has been isolated and characterized by scXRD. In addition to the facilitation of oxygen insertion reactions, UV irradiation can also affect the reactivity of other components in the reaction mixture, such as the solvent or other reaction products, which can result in further reactions. Labeling studies using [Pt(BPI)(CD3)] in chloroform have shown that photolytic reactions with oxygen involve degradation of the solvent.
- Britovsek, George J. P.,De Aguirre, Adiran,Ho, Sarah K. Y.,Lam, Francis Y. T.,Maseras, Feliu,White, Andrew J. P.
-
supporting information
p. 4077 - 4091
(2021/12/17)
-
- A photochemical C=C cleavage process: Toward access to backbone N-formyl peptides
-
Photo-responsive modifications and photo-uncaging concepts are useful for spatiotemporal control of peptides structure and function. While side chain photo-responsive modifications are relatively common, access to photo-responsive modifications of backbone N-H bonds is quite limited. This letter describes a new photocleavage pathway, affording N-formyl amides from vinylogous nitroaryl precursors under physiologically relevant conditions via a formal oxidative C=C cleavage. The N-formyl amide products have unique properties and reactivity, but are difficult or impossible to access by traditional synthetic approaches.
- Ball, Zachary T.,Wang, Haopei
-
p. 2932 - 2938
(2022/01/12)
-
- A platinum promoted Ag/SBA-15 catalyst effective in selective oxidation of methanol-design and surface characterization
-
The aim of this study was better understanding of surface properties of bimetallic (silver-platinum) catalysts and to verify if a very small addition of platinum (ca. 0.05 wt%) to silver (ca. 2.0 wt%) loaded on ordered mesoporous silica, SBA-15, would improve the catalytic properties of bimetallic Ag-Pt materials in selective oxidation of methanol to methyl formate. Ag-Pt catalysts were prepared by one-step and step-by-step procedures and the final Ag/Pt molar ratio in the respective samples was equal to 86 and 63. The catalysts were characterized after calcination and different activation treatments (in Ar and O2). X-ray diffraction, UV-vis and XP spectroscopy confirmed the lack of Ag-Pt alloy crystallites in the samples and also evidenced a higher resistance of silver oxide species to reduction upon activation in Ar flow in the presence of platinum promoter interacting with silver species. Methanol oxidation over the samples activated in Ar flow and in oxidizing flow (O2 + Ar) helped identify the role of each component in the bimetallic Ag-Pt catalyst in terms of activity and selectivity in the oxidation of methanol to methyl formate. A highly active bimetallic Pt/Ag/SBA-15 catalyst, selective to methyl formate and stable in methanol oxidation was constructed.
- Dziedzic, Izabela,Wisniewska, Joanna,Ziolek, Maria
-
p. 14570 - 14580
(2020/04/27)
-
- A method for producing formaldehyde or formic acid from methanol using photocatalyst
-
The present invention relates to a process for producing formaldehyde or formic acid by dehydrogenation from methanol in the presence of a photocatalyst carrying a cocatalyst. (MO)-supported photocatalystn -TiO2 The photocatalyst forms electrons upon exposure to light energy, and the cocatalyst uses electrons formed from the photocatalyst to generate hydrogen ions (H). + Reduced to hydrogen (H). 2 It is preferable that the reaction is carried out by light irradiation under an inert gas atmosphere or an oxygen-free atmosphere.
- -
-
Paragraph 0096-0099; 0104-0124
(2020/12/22)
-
- Endogenous X-C=O species enable catalyst-free formylation prerequisite for CO2reductive upgrading
-
CO2, the main component of greenhouse gas, is currently developed as a promising surrogate of carbon feedstock. Among various conversion routes, CO2undergoing catalytic reduction can furnish hydrogen/energy carriers and value-added chemicals, while specific metal-containing catalysts or organocatalysts are often prerequisite for smooth proceeding of the involved reaction processes. In this work, both formic acid and N-containing benzoheterocyclic compounds (including various benzimidazoles, benzothiazole, and benzoxazole) along with silanols could be synthesized with high yields (>90%) from catalyst-free reductive upgrading of CO2under mild conditions (50 °C). The endogenous X-CO species, derived from the N-methyl-substituted amide-based solvent [Me2N-C(O)-R], especially PolarClean, and O-formyl group [O-C(O)-H] of in situ formed silyl formate, were found to play a prominent promotional role in the activation of the used hydrosilane for reductive CO2insertion, as demonstrated by density functional theory (DFT) calculations and isotopic labeling experiments. Moreover, reaction mechanisms and condition-based sensitivity assessment were also delineated.
- Dai, Wenshuai,Li, Hu,Saravanamurugan, Shunmugavel,Wu, Hongguo,Yang, Song
-
supporting information
p. 5822 - 5832
(2020/10/21)
-
- Performance enhancing additives for reusable ruthenium-triphos catalysts in the reduction of CO2to dimethoxymethane
-
The direct access to dimethoxymethane (DMM) from CO2/H2 in MeOH is an attractive approach, but more active, selective, and robust catalyst systems are still desirable for an application of this system. Herein, we present the performance enhancing effect of additives on ruthenium-triphos catalyst systems for CO2 hydrogenation to DMM. In the presence of PPh3, functioning as both additional ligand and precursor for Lewis-acidic phosphonium salts, increased turnover numbers for DMM are achieved. Moreover, PPh3 significantly diminishes catalyst degradation via carbonylation to cationic [RuH(CO)2(triphos)]OTf, which remains an active species in the synthesis of DMM. Catalyst recycling over up to five runs with minimal loss in catalyst performance underlines the robustness of the system. Both, the recyclability of the system and the suppression of catalyst deactivation pathways encourage for application in sustainable continuous processes. This journal is
- Hashmi, A. Stephen K.,Jevtovikj, Ivana,Konrath, Robert,Paciello, Rocco A.,Schaub, Thomas,Sekine, Kohei
-
supporting information
p. 6464 - 6470
(2020/11/16)
-
- A Bioinspired Multicomponent Catalytic System for Converting Carbon Dioxide into Methanol Autocatalytically
-
Nature utilizes multicomponent catalyst systems to convert simple, abundant starting materials into complex molecules that are essential for life. In contrast, synthetic chemical transformations rarely adopt this strategy because it is difficult to replicate the sophisticated supramolecular assemblies used by biology for active-site separation and substrate trafficking. Here, we describe a method for multicomponent catalyst separation that involves encapsulating transition-metal complexes in nanoporous materials called metal-organic frameworks. The multicomponent catalyst system was highly active for converting hydrogen and carbon dioxide to methanol, and it could be formulated to be readily recyclable. Moreover, we uncovered an autocatalytic feature that was possible only when we utilized the multicomponent catalyst strategy. These results open avenues for obtaining fuel from abundant and renewable resources. Methanol is a promising renewable fuel that can be adapted to the current liquid fuel infrastructure. It can be produced from hydrogen and carbon dioxide, mitigating greenhouse gas emissions and storing hydrogen in the process. However, the industrial production of methanol through this hydrogenation reaction currently requires elevated temperatures and pressures and can produce significant amounts of unwanted byproducts. Here, we employ a bioinspired tandem catalytic system to efficiently hydrogenate carbon dioxide to methanol selectively at low temperatures. We achieved superior performance by eliminating catalyst incompatibility through encapsulating at least one of the catalysts involved in the tandem process in nanoporous materials called metal-organic frameworks. In the long term, this method could be applied to other tandem catalytic processes, allowing more efficient access to alternative fuels, commodity chemicals, and valuable pharmaceutical products. Tsung and co-workers describe a three-component tandem catalytic process for the hydrogenation of carbon dioxide to methanol. The bioinspired process is enabled by encapsulation of at least one of the two ruthenium-based catalysts required in the metal-organic framework (MOF) UiO-66. The reaction was found to have an autocatalytic feature that enables the reaction to be carried out without superstoichiometric additives. Encapsulating both ruthenium-based catalysts in the MOF allowed the catalyst to be recycled.
- Rayder, Thomas M.,Adillon, Enric H.,Byers, Jeffery A.,Tsung, Chia-Kuang
-
supporting information
p. 1742 - 1754
(2020/05/25)
-
- Methanol-Assisted Autocatalysis in Catalytic Methanol Synthesis
-
Catalytic methanol synthesis is one of the major processes in the chemical industry and may grow in importance, as methanol produced from CO2 and sustainably derived H2 are envisioned to play an important role as energy carriers in a future low-CO2-emission society. However, despite the widespread use, the reaction mechanism and the nature of the active sites are not fully understood. Here we report that methanol synthesis at commercially applied conditions using the industrial Cu/ZnO/Al2O3 catalyst is dominated by a methanol-assisted autocatalytic reaction mechanism. We propose that the presence of methanol enables the hydrogenation of surface formate via methyl formate. Autocatalytic acceleration of the reaction is also observed for Cu supported on SiO2 although with low absolute activity, but not for Cu/Al2O3 catalysts. The results illustrate an important example of autocatalysis in heterogeneous catalysis and pave the way for further understanding, improvements, and process optimization of industrial methanol synthesis.
- Christensen, Jakob M.,Jensen, Anker D.,Kuld, Sebastian,Nielsen, Niels D.,Sehested, Jens,Thrane, Joachim
-
supporting information
p. 18189 - 18193
(2020/08/19)
-
- Catalytic H2O2 activation by a diiron complex for methanol oxidation
-
In nature, C-H bond oxidation of CH4 involves a peroxo intermediate that decays to the high-valent active species of either a “closed” {FeIV(μ-O)2FeIV} core or an “open” {FeIV(O)(μO)FeIV(O)} core. To mimic and to obtain more mechanistic insight in this reaction mode, we have investigated the reactivity of the bioinspired diiron complex [(susan){Fe(OH)(μ-O)Fe(OH)}]2+ [susan = 4,7-dimethyl-1,1,10,10-tetrakis(2-pyridylmeth-yl)-1,4,7,10-tetraazadecane], which catalyzes CH3OH oxidation with H2O2 to HCHO and HCO2H. The kinetics is faster in the presence of a proton. 18O-labeling experiments show that the active species, generated by a decay of the initially formed peroxo intermediate [(susan){FeIII(μ-O)(μ-O2)FeIII}]2+, contains one reactive oxygen atom from the μ-oxo and another from the μ-peroxo bridge of its peroxo precursor. Considering an FeIVFeIV active species, a “closed” {FeIV(μ-O)2FeIV} core explains the observed labeling results, while a scrambling of the terminal and bridging oxo ligands is required to account for an “open” {FeIV(O)(μ-O)FeIV(O)} core.
- B?gge, Hartmut,Finke, Sebastian,Glaser, Thorsten,Ivanovic-Burmazovic, Ivana,Limpke, Thomas,Orth, Nicole,Stammler, Anja,Walleck, Stephan,Zimmermann, Thomas Philipp
-
supporting information
p. 15563 - 15569
(2020/11/20)
-
- Manipulating the surface composition of Pt-Ru bimetallic nanoparticles to control the methanol oxidation reaction pathway
-
The rational manipulation of reaction intermediates is crucial for achieving high-performance heterogeneous catalysis. Herein, using in situ Fourier transform infrared-diffuse reflection (FTIR) analysis, we report that the methanol oxidation reaction (MOR) intermediates can be controlled by precisely tuning the location and content of Ru on the Pt-Ru alloy surface.
- Wang, Qingmei,Chen, Siguo,Jiang, Jian,Liu, Jinxuan,Deng, Jianghai,Ping, Xinyu,Wei, Zidong
-
supporting information
p. 2419 - 2422
(2020/03/06)
-
- Effect of bimodal mesoporous carbon as PtRu catalyst support for direct methanol fuel cells
-
Mesoporous carbons (MCs) with different pore sizes were synthesized and evaluated as a catalyst support for fuel cells. The MCs were obtained from resorcinol-formaldehyde precursors, polymerized in the presence of polydiallyldimethylammonium chloride (cationic polyelectrolyte) as a structuring agent and commercial silica (Sipernat or Aerosil) as the hard template. The MC obtained with Aerosil shows a broad pore size distribution with a maximum at 21 nm. On the other hand, the MCs with Sipernat show a bimodal pore size distribution, with a narrow peak centered at 5 nm and a broad peak with a maximum ca. 30 nm. All MCs present a high specific surface area (800-1000 m2 g-1) and total pore volume ranging from 1.36 to 1.69 cm3 g-1. PtRu nanoparticles were deposited onto the MC support by an impregnation-reduction method with NaBH4 at 80 °C in basic media. The electrochemical characterization reveals improved electrocatalysis towards the methanol oxidation for the catalyst deposited over the carbon with the highest total pore volume. This catalyst also presented the highest CO2 conversion efficiency, ca. 80%, for the methanol oxidation as determined by differential electrochemical mass spectroscopy analysis. Moreover, the catalyst as a fuel cell anode showed the best performance, reaching a power density of 125 mW cm-2 at 90 °C with methanol as fuel and dry O2.
- Bruno, Mariano M.,Corti, Horacio R.,Fuentes-Quezada, Eduardo,Montiel, Gonzalo,Viva, Federico A.
-
p. 30631 - 30639
(2020/09/11)
-
- Molecular Zinc Hydride Cations [ZnH]+: Synthesis, Structure, and CO2 Hydrosilylation Catalysis
-
Protonolysis of [ZnH2]n with the conjugated Br?nsted acid of the bidentate diamine TMEDA (N,N,N′,N′-tetramethylethane-1,2-diamine) and TEEDA (N,N,N′,N′-tetraethylethane-1,2-diamine) gave the zinc hydride cation [(L2)ZnH]s
- Douair, Iskander,Maron, Laurent,Okuda, Jun,Ritter, Florian,Spaniol, Thomas P.
-
supporting information
p. 23335 - 23342
(2020/10/20)
-
- Excellent prospects in methyl methoxyacetate synthesis with a highly active and reusable sulfonic acid resin catalyst
-
Methyl methoxyacetate (MMAc) is a significant chemical product and can be applied as a gasoline and diesel fuel additive. This study aimed to achieve the industrial production of MMAc via dimethoxymethane (DMM) carbonylation. The effects of industrial DMM sources, reaction temperature, water content, pretreatment temperature, reaction pressure and time, the ratio of CO to DMM and recycle times were systematically investigated without any solvent. The conversion of DMM was 99.98% with 50.66% selectivity of MMAc at 393 K, 6.0 MPa reaction pressure, with the ratio of CO to DMM of only 1.97/1. When water was extracted from the DMM reactant, the MMAc selectivity significantly rose to 68.83%. This resin catalyst was reused for more than nineteen times in a slurry phase reactor and continuously performed for 300 h without noticeable loss of activity in a fixed bed reactor, displaying excellent stability. The mixed products were successfully separated by distillation, and 99.18% purity of MMAc was obtained. Therefore, the reported DMM carbonylation to MMAc process has an excellent basis for industrial application.
- Chen, Fei,Shi, Lei,Bello, SuleimanSabo,Fan, Jiaqi,Wang, Yan,Zhang, Dongxi,Yao, Jie
-
p. 1346 - 1353
(2020/02/04)
-
- High catalytic activity of CuY catalysts prepared by high temperature anhydrous interaction for the oxidative carbonylation of methanol
-
CuY catalysts were prepared by high temperature anhydrous interaction between NH4Y zeolite and copper(ii) acetylacetonate Cu(acac)2 and the activities were measured for the oxidative carbonylation of methanol to dimethyl carbonate under atmospheric pressure. The bulk and surface properties of the as-prepared catalyst were characterized by XRD, H2-TPR and XPS techniques. The activation atmosphere of the CuY catalyst and the testing temperature of the catalytic activity was systematically studied. During activation, nitrogen promotes the auto-reduction of Cu2+ to form the Cu+ active center, but deposited carbon on the surface of the CuY catalyst covers the active center, even plugging the channel, resulting in lower catalytic activity. Oxygen eliminates deposited carbon, but is not so good for the auto-reduction of Cu2+. Nitrogen doped with a small amount of oxygen not only eliminates the deposited carbon, but also promotes the auto-reduction of Cu2+ to form more Cu+ active centers. With the testing temperature increasing, the catalytic activity increases first and then decreases. When the testing temperature is 170 °C, the CuY catalyst with satisfactory activity and stability showed an excellent catalytic activity with 525.1 mg g-1 h-1 space time yield of DMC (STYDMC) and 18.9% methanol conversion. Then the longevity was investigated at 170 °C for 150 h. During the initial reaction period of 40 h, the STYDMC value was constant. In the next 20 h, the catalytic activity slightly decreased. But in the last 90 h, the catalytic performance is very stable and the STYDMC value remains 480 mg g-1 h-1. The main cause of deactivation is the growth of the particles.
- Wang, Yuchun,Liu, Zhaorong,Tan, Chao,Sun, Hong,Li, Zhong
-
p. 3293 - 3300
(2020/02/04)
-
- Glucose oxidation to formic acid and methyl formate in perfect selectivity
-
We report the highly remarkable discovery that glucose oxidation catalysed by polyoxometalates (POMs) in methanolic solution enables formation of formic acid and methyl formate in close to 100percent combined selectivity, thus with only negligible sugar oxidation to CO2. In detail, we report oxidation of a methanolic glucose solution using H8[PV5Mo7O40] (HPA-5) as catalyst at 90 °C and 20 bar O2 pressure. Experiments with 13C-labelled glucose confirm unambiguously that glucose is the only source of the observed formic acid and methyl formate formation under the applied oxidation conditions. Our results demonstrate a very astonishing solvent effect for the POM-catalysed glucose oxidation. In comparison to earlier work, a step-change in product yield and selectivity is achieved by applying an alcoholic reaction medium. The extremely high combined yields of formic acid and methyl formate greatly facilitate product isolation as low-boiling methyl formate (bp = 32 °C) can simply be isolated from the reaction mixture by distillation.
- Albert, Jakob,Bukowski, Anna,Kumpidet, Chiraphat,Maerten, Stephanie,Vo?, Dorothea,Wasserscheid, Peter
-
p. 4311 - 4320
(2020/07/14)
-
- Photochemistry of a 9-Dithianyl-Pyronin Derivative: A Cornucopia of Reaction Intermediates Lead to Common Photoproducts
-
Leaving groups attached to the meso-methyl position of many common dyes, such as xanthene, BODIPY, or pyronin derivatives, can be liberated upon irradiation with visible light. However, the course of phototransformations of such photoactivatable systems can be quite complex and the identification of reaction intermediates or even products is often neglected. This paper exemplifies the photochemistry of a 9-dithianyl-pyronin derivative, which undergoes an oxidative transformation at the meso-position to give a 3,6-diamino-9H-xanthen-9-one derivative, formic acid, and carbon monoxide as the main photoproducts. The course of this multi-photon multi-step reaction was studied under various conditions by steady-state and time-resolved optical spectroscopy, mass spectrometry and NMR spectroscopy to understand the effects of solvents and molecular oxygen on individual steps. Our analyses have revealed the existence of many intermediates and their interrelationships to provide a complete picture of the transformation, which can bring new inputs to a rational design of new photoactivatable pyronin or xanthene derivatives.
- Martínek, Marek,Váňa, Ji?í,?ebej, Peter,Navrátil, Rafael,Slanina, Tomá?,Ludvíková, Lucie,Roithová, Jana,Klán, Petr
-
p. 2230 - 2242
(2020/08/05)
-
- PROCESS FOR THE PRODUCTION OF ACETALS FROM CARBON DIOXIDE
-
The invention relates to a process for the preparation of acetals from carbon dioxide. The invention also relates to a mixture of phosphorus containing ligands comprising least one polydentate ligand and at least one monodentate ligand. Further, the invention also relates to the use of mixtures comprising at least one polydentate ligand and at least one monodentate ligand in transition metal complexes for the preparation of acetals.
- -
-
Page/Page column 31-32
(2020/08/22)
-
- Acid catalysis in confined channels of metal-organic frameworks: Boosting orthoformate hydrolysis in basic solutions
-
Enzymes use a confined docking cavity and residual groups in the cavity to regulate substrate selectivity and catalytic activity. By mimicking enzymes, we herein report that metal-organic framework (MOF) KLASCC-1, with channels and inside-channel pyridyl groups, can promote orthoformate hydrolysis in basic solutions. By studying pH-dependent hydrolysis and using an analogue MOF that lacks inside-channel pyridyl groups, we proved protonated pyridyl groups as acid catalytic sites for orthoformate hydrolysis. By using MOFs with only open pyridyl groups, we demonstrated the necessity of the confined channels. X-ray diffraction structures of KLASCC-1 with encapsulated substrates confirmed that these channels can regulate activity and size selectivity. Recycling tests and crystallographic studies confirmed that KLASCC-1 kept its framework structure in catalysis. This work shows the potentials of using MOFs for host-guest catalysis that cannot be otherwise completed and underlines the advantages of using crystal engineering to identify active sites.
- Zhou, Guojun,Wang, Bo,Cao, Rui
-
supporting information
p. 14848 - 14853
(2020/10/13)
-
- PRECURSOR COMPOUNDS OF ESTER COMPOUNDS
-
The present disclosure relates to compounds of the formula (I) which are precursor compounds of esters, whereby upon hydrolysis of the precursor compound, an ester compound is released. This ester precursor approach can be useful for applications where controlled release of, for example, ethyl formate, is beneficial.
- -
-
Paragraph 00131-00132
(2020/12/30)
-
- Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions
-
Supported transition metal catalysts have been extensively applied to oxidative and reductive processes. The understanding of surface speciation and active site-support interactions in these materials play a substantial role in developing improved heterogeneous catalysts. Herein, a series of impregnated 3D ferrierite and 2D ITQ-6 siliceous supports with variable loading of vanadium oxide was prepared. Chemical and structural properties of the materials were studied by X-ray diffraction, N2 physisorption, inductively coupled plasma – optical emission spectrometry, X-ray absorption, Fourier transform infrared and diffuse reflectance UV-vis spectroscopies, and temperature-programmed reduction with H2. Reactivity of the catalyst surface, associated with the incidence of isolated silanol groups, was found to be more effective when vanadium oxides were better dispersed and stabilized than increases in surface area. Differences in activation and the oxidation state dynamic behavior of active sites were then probed by methanol oxidation as a model reaction monitored by in situ FTIR spectroscopy and XANES/MS. By applying isothermal periods of reaction under non-oxidizing atmosphere and regeneration of catalysts by O2, it was found that, even at distinct rates, all types of sites are accessible during reaction, since a complete reduction to V4+ was observed. However, reoxidation of sites to V5+ is limited and sensitive to the different vanadium species on the surface, and probably, the determinant factor of the distinct V5+/V4+ equilibrium reached for the catalysts when the reaction is carried out under constant oxidizing atmosphere.
- Vieira, Luiz H.,Possato, Luiz G.,Chaves, Thiago F.,Lee, Jason J.,Sulmonetti, Taylor P.,Jones, Christopher W.,Martins, Leandro
-
p. 141 - 151
(2019/11/13)
-
- Selectivity switch in transformation of CO2 from ethanol to methanol on Cu embedded in the defect carbon
-
The copper-based catalysts have been generally regarded as high-performance catalysts for CO2 hydrogenation toward methanol, while the production of ethanol via C-C coupling on the copper-based catalysts is still challenging. Herein, we report a new catalyst where Cu nanoparticles are embedded in the carbon support with abundant defect sites, achieving a high selectivity for ethanol in the CO2 hydrogenation. The experiments coupled with the theoretical studies show a clear map where carbon defects serve as anchor sites that can stabilize interfacial copper species, and interfacial Cu sites with low coordination numbers can adsorb two C1 species and later convert them to a C2 species via a hydrogenation-induced coupling reaction. Further adjacent Cu atoms of interfacial Cu sites can facilitate OH reduction reactions via the Cu-Cu bridge adsorption to assist the formation of ethanol. Especially, those specific active sites easily disappear in the reducing conditions and during the reaction, the major product can transform from ethanol to methanol.
- Li, Shuohao,Saranya, Govindarajan,Chen, Mingyang,Zhu, Yan
-
p. 722 - 730
(2020/04/23)
-
- Utilization of Formic Acid as C1 Building Block for the Ruthenium-Catalyzed Synthesis of Formaldehyde Surrogates
-
Dialkoxymethanes are becoming increasingly important as fuel additives, formaldehyde surrogates, and chemical intermediates, but the effective synthesis remains challenging. Herein, the catalytic synthesis of dialkoxymethane products using a molecular catalyst is reported. The catalytic system, comprising the [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3, enables the direct synthesis of dialkoxymethane products with formic acid as C1 building block in high to excellent turnover numbers.
- Beydoun, Kassem,Thenert, Katharina,Wiesenthal, Jan,Hoppe, Corinna,Klankermayer, Jürgen
-
p. 1944 - 1947
(2020/04/08)
-
- Synthesis of High Dimensionally Structured Mo-Fe Mixed Metal Oxide and Its Catalytic Activity for Selective Oxidation of Methanol
-
High-dimensionally structured Mo-Fe oxide (HDS-MoFeO) was synthesized through an assembly of structural units supplied from Keplerate-type polyoxometalate, {Mo72Fe30}, under an appropriate hydrothermal condition. HDS-MoFeO showed excellent catalytic activity for the selective oxidation of methanol with slightly lower selectivity for formaldehyde than that of a conventional Mo-Fe oxide catalyst.
- Hiyoshi, Norihito,Ishikawa, Satoshi,Kumaki, Masahiro,Shimoda, Kosuke,Tashiro, Masaya,Ueda, Wataru
-
supporting information
(2020/04/15)
-
- CuO/TiO2 heterojunction composites: An efficient photocatalyst for selective oxidation of methanol to methyl formate
-
This study demonstrates the synthesis of an efficient photocatalyst, CuO/TiO2 heterojunction, for selective aerobic photo-oxidation of methanol to methyl formate. The CuO nanoparticles (size: 3.5 ± 1.0 nm) are particularly deposited at the {101} facet of anatase TiO2 nanosheets to minimize recombination of photo-generated electrons/holes. The photocatalysts are characterized by different methods, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, and hydrogen temperature-programmed reduction (H2-TPR). The heterojunction catalysts exhibit an excellent photocatalytic performance under mild conditions (i.e., 25-45 °C and gas reactions under UV irradiation with a wavelength of 365 nm) for the selective photo-oxidation of methanol using 0.5 vol% oxygen (O2) as an oxidizing agent. The 5 wt% CuO/TiO2 photocatalyst exhibits a decent 95% methanol conversion with over 85% selectivity towards the formation of methyl formate. The by-product of the reaction is found to be merely CO2, which can be readily eliminated from the product. The formation rate for the methyl formate is 10.8 mmol g-1 h-1 at 25 °C, which is considerably higher than that for the corresponding CuO and TiO2 nanosheets as well as for conventional catalysts. The superior catalytic activity of the CuO/TiO2 is associated with its unique electronic structure and the synergistic effects at the interface of the photocatalysts' components. The results of this study offer guidelines for design of a new synthetic strategy for preparation of efficient photocatalysts for selective oxidation of methanol to methyl formate and related reactions.
- Shi, Quanquan,Ping, Guicheng,Wang, Xiaojia,Xu, Hui,Li, Jingmei,Cui, Jiaqi,Abroshan, Hadi,Ding, Hongjing,Li, Gao
-
p. 2253 - 2260
(2019/02/05)
-
- HOMOGENEOUS IRON CATALYSTS FOR THE CONVERSION OF METHANOL TO METHYL FORMATE AND HYDROGEN
-
Iron-based homogeneous catalysts, supported by pincer ligands, are employed in the catalytic dehydrocoupling of methanol to produce methyl formate and hydrogen. As both methanol and methyl formate are volatile materials, they can be readily separated from the catalyst by applying vacuum at room temperature. The hydrogen by-product of the reaction may be isolated and utilized as a feedstock in other chemical transformations.
- -
-
Paragraph 0082-0093
(2019/02/15)
-
- Base-Free Hydrogenation of Carbon Dioxide to Methyl Formate with a Molecular Ruthenium-Phosphine Catalyst
-
Herein, a molecular ruthenium-phosphine catalyst system for the effective base-free methyl formate production from carbon dioxide is described. In detail, the novel [Ru(N-triphosCy)(tmm)] complex, bearing sterically demanding cyclohexyl groups in the triphos-ligand structure, enabled in combination with the Lewis acid Al(OTf)3 the selective transformation of carbon dioxide to methyl formate with unprecedented activity. From a mechanistic perspective, in the initial step formic acid is formed, undergoing a consecutive Lewis acid promoted esterification with methanol to methyl formate. This selective transformation with carbon dioxide paves the way to versatile processes for important C1 building blocks.
- Westhues, Niklas,Belleflamme, Maurice,Klankermayer, Jürgen
-
p. 5269 - 5274
(2019/07/12)
-
- CuO-decorated dual-phase TiO2 microspheres with enhanced activity for photocatalytic CO2 reduction in liquid–solid regime
-
Copper oxide (CuO)-decorated anatase and TiO2(B) dual-phase titania microsphere (CuO/TiO2(AB)) photocatalysts were synthesized using a facile two-step approach. The photocatalytic reduction of CO2 to form methyl formate (MF) in methanol was evaluated. The results indicated that the CuO-decorated dual-phase TiO2 microspheres displayed MF yield of 1800 μmol·g?1 under 4 h illumination, higher than other reference photocatalysts, due to its mixed-phase heterojunction structure and larger surface area, thus leading to an enhanced UV-light response, effective separation and low recombination rate of the photoinduced charge carriers. CuO/TiO2(AB) also showed good stability with the MF yield reproducibility greater than 90% in cyclic runs.
- Zhao, Yunxia,Chen, Jiaxin,Cai, Wei,Bu, Yunfei,Huang, Qiong,Tao, Tao,Lu, Jiangang
-
-
- PROCESS FOR MAKING FORMIC ACID UTILIZING LOWER-BOILING FORMATE ESTERS
-
Disclosed is a process for recovering formic acid from a formate ester of a C3 to C4 alcohol. Disclosed is also a process for producing formic acid by carbonylating a C3 to C4 alcohol, hydrolyzing the formate ester of the alcohol, and recovering a formic acid product. The alcohol may be dried and returned to the reactor. The process enables a more energy efficient production of formic acid than the carbonylation of methanol to produce methyl formate.
- -
-
Paragraph 00182; 00183
(2019/02/15)
-
- Methylformate from CO2: An integrated process combining catalytic hydrogenation and reactive distillation
-
An integrated two-step process for the production of methylformate (MF) from CO2, H2 and MeOH was developed. In the first step, the hydrogenation of CO2 to a formate-amine adduct is carried out in a biphasic system comprising n-decane as the catalyst phase and MeOH as the product phase. In the second step, the resulting methanol solution containing the formate-amine adduct is subjected to reactive distillation for esterification and isolation of methylformate. The selection of the amine played an important role for devising the overall process. Whereas in the hydrogenation step basic amines work best, medium to low basic amines are preferred in the esterification step. 1,2-Dimethyl-imidazole (1,2-DMI) was identified as an effective compromise for the integration of both steps. In the hydrogenation step, a bis(diphenylphosphino)methane ligand tailored with long alkyl chains ensured effective retention of the Ru-catalyst in the non-polar phase allowing straightforward reuse of the catalyst phase. In a semi-continuous set-up, repetitive hydrogenation (8 cycles) led to a total turnover number (TTON) of 38?000 at an average turnover frequency (TOF) of 1400 h-1 with a cumulative catalyst leaching of only 1.4 mol% for P and 2.0 mol% for Ru. Reactive distillation was demonstrated in a continuously operated rectification unit leading to the isolation of MF at the head of the column with a purity of 91.5%.
- Scott, Martin,Westhues, Christian G.,Kaiser, Teresa,Baums, Janine C.,Jupke, Andreas,Franciò, Giancarlo,Leitner, Walter
-
supporting information
p. 6307 - 6317
(2019/12/03)
-
- Molecularly Defined Manganese Catalyst for Low-Temperature Hydrogenation of Carbon Monoxide to Methanol
-
Methanol synthesis from syngas (CO/H2 mixtures) is one of the largest manmade chemical processes with annual production reaching 100 million tons. The current industrial method proceeds at high temperatures (200-300 °C) and pressures (50-100 atm) using a copper-zinc-based heterogeneous catalyst. In contrast, here, we report a molecularly defined manganese catalyst that allows for low-temperature/low-pressure (120-150 °C, 50 bar) carbon monoxide hydrogenation to methanol. This new approach was evaluated and optimized by quantum mechanical simulations virtual high-throughput screenings. Crucial for this achievement is the use of amine-based promoters, which capture carbon monoxide to give formamide intermediates, which then undergo manganese-catalyzed hydrogenolysis, regenerating the promoter. Following this conceptually new approach, high selectivity toward methanol and catalyst turnover numbers (up to 3170) was achieved. The proposed general catalytic cycle for methanol synthesis is supported by model studies and detailed spectroscopic investigations.
- Ryabchuk, Pavel,Stier, Kenta,Junge, Kathrin,Checinski, Marek P.,Beller, Matthias
-
supporting information
p. 16923 - 16929
(2019/10/28)
-
- Selective Hydrogenation of CO2 Dictated by Isomers in Au28(SR)20 Nanoclusters: Which One is Better?
-
It is a challenge to make clear how isomerism in a heterogeneous catalyst induces distinct differences in catalytic properties, as attainment of the structural isomerism in a conventional catalyst is difficult. By successfully identifying the isomerism in the atomically precise Au nanoclusters, an exciting opportunity for unravelling catalysis of isomeric catalysts is opened up. Herein, we report that the isomerism in the Au28(SR)20 nanoclusters with different surface atom arrangements can indeed render different catalytic behaviors in the selective hydrogenation of CO2. We anticipate that our studies will serve as a starting point for fundamental investigations about how to control the catalytic activity and selectivity by the isomerism-induced catalysis.
- Xu, Jiayu,Chen, Mingyang,Zhu, Yan
-
supporting information
p. 9185 - 9190
(2019/07/09)
-
- Application of Hetero-Triphos Ligands in the Selective Ruthenium-Catalyzed Transformation of Carbon Dioxide to the Formaldehyde Oxidation State
-
Due to the increasing demand for formaldehyde as a building block in the chemical industry as well as its emerging potential as feedstock for biofuels in the form of dimethoxymethane and the oxymethylene ethers produced therefrom, the catalytic transformation of carbon dioxide to the formaldehyde oxidation state has become a focus of interest. In this work, we present novel ruthenium complexes with hetero-triphos ligands, which show high activity in the selective transformation of carbon dioxide to dimethoxymethane. We substituted the apical carbon atom in the backbone of the triphos ligand platform with silicon or phosphorus and optimized the reaction conditions to achieve turnover numbers as high as 685 for dimethoxymethane. The catalytic systems could also be tuned to preferably yield methyl formate with turnover numbers of up to 1370, which in turn can be converted into dimethoxymethane under moderate conditions.
- Seibicke, Max,Siebert, Max,Siegle, Alexander F.,Gutenthaler, Sophie M.,Trapp, Oliver
-
supporting information
p. 1809 - 1814
(2019/04/25)
-
- Selective Ruthenium-Catalyzed Transformation of Carbon Dioxide: An Alternative Approach toward Formaldehyde
-
Formaldehyde is an important precursor to numerous industrial processes and is produced in multimillion ton scale every year by catalytic oxidation of methanol in an energetically unfavorable and atom-inefficient industrial process. In this work, we present a highly selective one-step synthesis of a formaldehyde derivative starting from carbon dioxide and hydrogen gas utilizing a homogeneous ruthenium catalyst. Here, formaldehyde is obtained as dimethoxymethane, its dimethyl acetal, by selective reduction of carbon dioxide at moderate temperatures (90 °C) and partial pressures (90 bar H2/20 bar CO2) in the presence of methanol. Besides the desired product, only methyl formate is formed, which can be transformed to dimethoxymethane in a consecutive catalytic step. By comprehensive screening of the catalytic system, maximum turnover numbers of 786 for dimethoxymethane and 1290 for methyl formate were achieved with remarkable selectivities of over 90% for dimethoxymethane.
- Siebert, Max,Seibicke, Max,Siegle, Alexander F.,Kr?h, Sabrina,Trapp, Oliver
-
supporting information
p. 334 - 341
(2019/01/16)
-
- Chemical Versatility of [FeFe]-Hydrogenase Models: Distinctive activity of [μ-C6H4-1,2-(κ2-S)2][Fe2(CO)6] for electrocatalytic CO2 reduction
-
The [FeFe]-hydrogenase model, [(μ-bdt)Fe2(CO)6] (1, bdt = benzene-1,2-dithiolato), displays distinctive activity from its analogous complex, [(μ-edt)Fe2(CO)6] (2, edt = ethane-1,2-dithiolato), for electrochemical CO2 reduction in acetonitrile with methanol or water as proton source. The maximum turnover frequency of 195 s-1 estimated for 1 is more than 4800 times higher than that of 2. The influence of reaction conditions on faradaic yield and product selectivity was investigated. Controlled potential electrolysis experiments of 1 under optimal conditions gave a good faradaic yield of 88%, with formic acid as major product (selectivity ≈81%) together with a small amount of CO (selectivity ≈ 11%) and H2 (selectivity ≈ 8%). Density functional theory calculations suggest a mechanism of bimetal synergistic catalysis for electrochemical CO2 reduction by 1.
- Cheng, Minglun,Yu, Yang,Zhou, Xin,Luo, Yi,Wang, Mei
-
p. 768 - 774
(2019/01/14)
-
- Trithioorthoester Exchange and Metathesis: New Tools for Dynamic Covalent Chemistry
-
To expand the toolbox of dynamic covalent and systems chemistry, we investigated the acid-catalyzed exchange reaction of trithioorthoesters with thiols. We found that trithioorthoester exchange occurs readily in various solvents in the presence of stoichiometric amounts of strong Bronsted acids or catalytic amounts of certain Lewis acids. The scope of the exchange reaction was explored with various substrates, and conditions were identified that permit clean metathesis reactions between two different trithioorthoesters. One distinct advantage of S, S, S-orthoester exchange over O, O, O-orthoester exchange is that the exchange reaction can kinetically outcompete hydrolysis, thereby making the process less sensitive to residual moisture. We expect that the relatively high stability of the products might be beneficial in future supramolecular receptors or porous materials.
- Bothe, Michael,Furlan, Ricardo L. E.,Orrillo, A. Gastón,Von Delius, Max
-
p. 1988 - 1994
(2019/10/22)
-
- Method for synthesizing propionate through ester-ester exchange path
-
The invention provides a method for synthesizing propionate through an ester-ester exchange path and relates to a method for synthesizing the propionate. According to the method, reaction raw materials include, but are not limited to ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate and the like; the method for synthesizing the propionate through an ester exchange one-step method is adopted. A catalyst comprises alkaline materials including ionic liquid, soluble strong base, solid base and the like respectively; the catalyst has the advantages of high catalysis efficiency and no pollution. By taking methyl propionate and ethyl acetate reaction as an example, KOH is used as the catalyst, the mol ratio of the raw materials is 1 to 1, the reaction temperature is 60 DEG C and the reaction time is 5 min; the conversion ratios of the methyl propionate and the ethyl acetate can reach 70 percent or more; products comprise ethyl propionate and the methylacetate. The whole reaction path has the characteristics of short synthetic route, simple technological flow and high yield and the catalyst is stable, does not become inactive and can be repeatedlyutilized.
- -
-
Paragraph 0030-0031
(2019/04/04)
-
- The carbonylation of dimethyl ether catalyzed by supported heteropoly acids: The role of Br?nsted acid properties
-
The carbonylation of dimethyl ether (DME) to methyl acetate (MA) is a vital step in a direct route of ethanol production from syngas. Heteropoly acids (HPAs) as a kind of solid acid catalysts can facilitate the reaction. To improve the accessibility of Br?nsted acid sites, we prepared a series of supported HPAs catalysts by wetness impregnation on SBA-15. The impact of the HPAs loading and composition on the textural structure and acidic properties was investigated by comparing with the bulk HPAs. Taking acidity analysis (Pyridine-IR and TPD) and catalytic measurement results, we explored the effect of the amount and strength of Br?nsted acid site on this reaction. The observations demonstrated that more and stronger acid sites are prone to MA formation.
- Shen, Hongbao,Li, Ying,Huang, Shouying,Cai, Kai,Cheng, Zaizhe,Lv, Jing,Ma, Xinbin
-
p. 117 - 123
(2018/04/20)
-
- Sustainable Co-Synthesis of Glycolic Acid, Formamides and Formates from 1,3-Dihydroxyacetone by a Cu/Al2O3 Catalyst with a Single Active Sites
-
Glycolic acid (GA), as important building block of biodegradable polymers, has been synthesized for the first time in excellent yields at room temperature by selective oxidation of 1,3-dihyroxyacetone (DHA) using a cheap supported Cu/Al2O3 catalyst with single active CuII species. By combining EPR spin-trapping and operando ATR-IR experiments, different mechanisms for the co-synthesis of GA, formates, and formamides have been derived, in which .OH radicals formed from H2O2 by a Fenton-like reaction play a key role.
- Dai, Xingchao,Adomeit, Sven,Rabeah, Jabor,Kreyenschulte, Carsten,Brückner, Angelika,Wang, Hongli,Shi, Feng
-
supporting information
p. 5251 - 5255
(2019/03/07)
-
- Direct Synthesis of Methyl Formate from CO2 With Phosphine-Based Polymer-Bound Ru Catalysts
-
Methyl formate was produced in one pot through the hydrogenation of CO2 to formic acid/formate followed by an esterification step. The route offers the possibility to integrate renewable energy into the fossil-based chemical value chain. In this work, a phosphine-polymer-anchored Ru complex was shown to be an efficient solid catalyst for the direct hydrogenation of CO2 to methyl formate. The 1,2-bis(diphenylphosphino)ethane-like polymer presented the highest activity with a turnover number (TON) of up to 3401 at 160 °C. The reaction parameters were systemically investigated to optimize the reaction towards the formation of methyl formate. This catalyst could be reused seven times without a significant decrease in activity. Evolution of the catalytic Ru center during the reaction was revealed, and a possible reaction mechanism was proposed.
- Sun, Ruiyan,Kann, Anna,Hartmann, Heinrich,Besmehn, Astrid,Hausoul, Peter J. C.,Palkovits, Regina
-
p. 3278 - 3285
(2019/06/13)
-
