- An easily accessible Re-based catalyst for the selective conversion of methanol: Evidence for an unprecedented active site structure through combined operando techniques
-
Heterogeneous Re/SiO2 catalysts prepared using a one pot sol-gel synthesis were found to display high activity in the direct, selective methanol conversion to methylal, which is correlated to an unprecedented rhenium oxide structure.
- Yoboue, Anthony,Susset, Audrey,Tougerti, Asma,Gallego, Daniel,Ramani, Sudarsan Venkat,Kalyanikar, Malathi,Dolzhnikov, Dmitriy S.,Wubshet, Sileshi G.,Wang, Yilun,Cristol, Sylvain,Briois, Valerie,La Fontaine, Camille,Gauvin, Regis. M.,Paul, Jean-Franois,Berrier, Elise
-
-
Read Online
- Carbon molecular sieves as catalysts and catalyst supports
-
Ultrahigh surface area (>2500 m2/g) carbon molecular sieves (CMS's) are shown to be very effective catalysts and catalyst supports for the oxidative dehydrogenation and dehydration of a variety of substrates. Studies of methanol, ethanol, 1- and 2-propanol, and propanal provide mechanistic insight concerning the reactivity of these materials. The activities are superior to many inorganic oxide based systems. As catalysts, CMS systems are shown to have the ability to function via hydride or hydrogen atom abstraction mechanisms, depending on the nature of the substrate. As catalyst supports, a synergism is demonstrated between the CMS support and metal dopants, which enables the system to have greater activity than that of either of the constituents alone. The highly reactive surface, the ability to disperse and stabilize metal clusters, and the extraordinary adsorption capabilities of the CMS materials are the key contributors to their high activity. One of the catalysts studied (a 15% MoO3/CMS system) has pronounced activity toward methanol oxidation: 70% of the substrate is converted to methyl formate in a single pass with over 95% selectivity. A further significant finding involves the metal-catalyzed conversion of the carbonaceous support itself to small molecular weight products via reactions with methanol fragments. This finding has fundamental implications in heterogeneous catalyzed CO reductions and in the conversion of methanol to gasoline in zeolites.
- Grunewald, Gerald C.,Drago, Russell S.
-
-
Read Online
- Niobium-substituted octahedral molecular sieve (OMS-2) materials in selective oxidation of methanol to dimethoxymethane
-
Octahedral molecular sieve (OMS-2) refers to a one-dimensional 2 × 2 framework of octahedral manganese oxo units based on the cryptomelane-type framework. Herein, we describe a niobium (Nb) substituted mixed metal oxide of Nb and Mn where the cryptomelane-type framework is retained. These materials are hydrothermally synthesized from the reaction of potassium permanganate, manganese sulfate, and homogeneous niobium(v) precursors. Niobium incorporation up to 31 mol% can be achieved without destroying the one dimensional 2 × 2 framework. The yields of the materials vary between 70 and 90%. These materials are analyzed by powder XRD, BET isotherm, TEM, SEM, XRF, and XPS studies. The synthesized materials show promising activity in selective oxidation of methanol to dimethoxymethane (DMM) at 200 °C. Normalized activity correlations followed the trend 21% Nb-OMS-2 > 15% Nb-OMS-2 > 31% Nb-OMS-2 > 68% Nb-OMS-2 > K-OMS-2. A fluctuation in methanol conversion was observed around 125-150 °C in most samples, suggesting this to be a catalytically important temperature regime when forming active sites for DMM production.
- Wasalathanthri, Niluka D.,Guild, Curtis,Nizami, Quddus A.,Dissanayake, Shanka L.,He, Junkai,Kerns, Peter,Fee, Jared,Achola, Laura,Rathnayake, Dinithi,Weerakkody, Chandima,Suib, Steven L.,Nandi, Partha
-
-
Read Online
- Kinetic relationships in synthesis of dimethoxymethane
-
The kinetics of formation of dimethoxymethane by acetalization of formaldehyde with methanol, catalyzed by silicotungstic heteropoly acid, were studied.
- Danov,Kolesnikov,Logutov
-
-
Read Online
- Synthesis of propylene from renewable allyl alcohol by photocatalytic transfer hydrogenolysis
-
Photochemical transformation of biomass-derived or renewable substances with promising scalability is an important challenge for promoting green and sustainable chemistry. We report here that photocatalytic transfer hydrogenolysis of allyl alcohol (obtained from glycerol) gives potentially sustainable propylene with high chemo- and redox selectivity, promoted by powdered Pd/TiO2 in CH3OH (obtained from CO2) under near-ultraviolet-visible light irradiation (λ > 365 nm) at ambient temperature.
- Caner, Joaquim,Liu, Zijun,Takada, Yuki,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
-
-
Read Online
- Direct Synthesis of Hydrogen and Dimethoxylmethane from Methanol on Copper/Silica Catalysts with Optimal Cu+/Cu0 Sites
-
Hydrogen is an important sustainable resource, and here we report a catalytic route for the direct production of hydrogen (with a purity of 95 %) and dimethoxylmethane (DMM) from supercritical methanol over a Cu/SiO2 catalyst prepared by deposition–precipitation with ammonia (DPA) at 240°C in a one-pot process. The procedure starts with methanol dehydrogenation to hydrogen and formaldehyde at the interface of the Cu2O?SiO2–Cu0 particle mixture, and subsequently, the formaldehyde intermediate condenses with substantial methanol to form DMM in the liquid phase. The Cu0, CuO, and chrysocolla species are inactive for hydrogen generation from methanol, and the intrinsic active species for methanol decomposition is the Cu2O?SiO2–Cu0 nanoparticle interface, which is produced from the hydrogen reduction of Cu2Si2O5(OH)2 or from the methanol reduction of Cu?O?Si moieties. A correlation between the structure and activity on reduced Cu/SiO2 (DPA) suggested that only Cu0 was not active, but the combined Cu0 and Cu+ sites with interfaces on SiO2 with an optimal Cu+/Cu0 ratio of 1.56 were highly active for methanol dehydrogenation and subsequent condensation steps. The developed new catalytic system offers a facile and atom-economical way to generate pure hydrogen (almost CO free) from liquid methanol that can be used in fuel cell and hydrogen-involved biomass reactions.
- Wu, Liubi,Li, Bolong,Zhao, Chen
-
-
Read Online
- A Composite Fe–V/g-C3N4 for Liquid-Phase Selective Oxidation of Methanol with O2 Oxidant
-
Abstract: A composite material Fe–V/g-C3N4 prepared by impregnation achieved an efficient performance for heterogeneously catalytic oxidation of methanol to dimethoxymethane (DMM) and poly(oxymethylene) dimethyl ethers (POM) by O2 oxidant in batch reactor, exhibiting 34.3% conversion and > 99.0% selectivity to DMM and POM. However, a pioneered strategy for tuneable synthesis of DMM and POM was realized by controlling the reaction time. The experimental results revealed that FeVO4 and V2O5 nanoparticle crystallizes served as the active sites and higher specific areas 29.3–51.9 m3/g for the catalysts were jointly responsible for the high activity. Besides, the catalyst could be easily recovered and effectively reused. Graphic Abstract: A composite material Fe–V/g-C3N4 with higher specific area exhibited efficient performance for heterogeneously catalytic oxidation of methanol to dimethoxymethane (DMM) and polyoxymethylene dimethyl ether (POM) in batch reactor using O2 oxidant. Moreover, a pioneered strategy for tunable synthesis of DMM and POM was realized by controlling the reaction time. The catalyst was easily recovered and had excellent recycle lifetime and stability. [Figure not available: see fulltext.]
- Zhang, Jing,Wang, Hongxia,Lu, Bin,Zhao, Jingxiang,Cai, Qinghai
-
-
Read Online
- Highly selective oxidation of methanol to dimethoxymethane over SO42-/V2O5-ZrO2
-
The sulfated vanadia-zirconia SO42-/V2O5-ZrO2 catalyst, prepared by an impregnation method and calcined at various temperatures, was found to have a high catalytic activity for methanol oxidation to dimethoxymethane in a fixed bed reactor and a batch autoclave using O2 as the oxidant due to the crystalline V2O5 dispersed on the surface as redox active sites, as well as stronger acidic sites.
- Tao, Meng,Wang, Hongxia,Lu, Bin,Zhao, Jingxiang,Cai, Qinghai
-
-
Read Online
- Amorphous oxide as a novel efficient catalyst for direct selective oxidation of methanol to dimethoxymethane
-
We report for the first time the use of an amorphous oxide catalyst for the selective oxidation of methanol in the gas phase, leading at 553 K to the production of dimethoxymethane with a selectivity as high as 90% at high methanol conversion (68%). The Royal Society of Chemistry.
- Royer, Sebastien,Secordel, Xavier,Brandhorst, Markus,Dumeignil, Franck,Cristol, Sylvain,Dujardin, Christophe,Capron, Mickael,Payen, Edmond,Dubois, Jean-Luc
-
-
Read Online
- Initial Carbon–Carbon Bond Formation during the Early Stages of the Methanol-to-Olefin Process Proven by Zeolite-Trapped Acetate and Methyl Acetate
-
Methanol-to-olefin (MTO) catalysis is a very active field of research because there is a wide variety of sometimes conflicting mechanistic proposals. An example is the ongoing discussion on the initial C?C bond formation from methanol during the induction period of the MTO process. By employing a combination of solid-state NMR spectroscopy with UV/Vis diffuse reflectance spectroscopy and mass spectrometry on an active H-SAPO-34 catalyst, we provide spectroscopic evidence for the formation of surface acetate and methyl acetate, as well as dimethoxymethane during the MTO process. As a consequence, new insights in the formation of the first C?C bond are provided, suggesting a direct mechanism may be operative, at least in the early stages of the MTO reaction.
- Chowdhury, Abhishek Dutta,Houben, Klaartje,Whiting, Gareth T.,Mokhtar, Mohamed,Asiri, Abdullah M.,Al-Thabaiti, Shaeel A.,Basahel, Suliman N.,Baldus, Marc,Weckhuysen, Bert M.
-
-
Read Online
- Studies of S -But-3-ynyl and gem -dimethyl S -But-3-ynyl thioglycoside donors in gold-catalyzed glycosylations
-
Gold-catalyzed glycosylation using S-but-3-ynyl and gem-dimethyl S-but-3-ynyl thioglycoside donors has been investigated for the synthesis of various types of complex oligosaccharides. It was found that 2,2-dimethyl S-but-3-ynyl thioglycoside donors are m
- Adhikari, Surya,Li, Xiaohua,Zhu, Jianglong
-
-
Read Online
- Unsensitized photooxidation of sulfur compounds with molecular oxygen in solution
-
The short wavelength irradiation of aliphatic disulfides, sulfides and of n-butanethiol in alcohols or aqueous acetonitrile in the presence of oxygen was investigated: the corresponding sulfonic acids are produced in good yields for short alkyl chain compounds, together with smaller amounts of sulfuric and carboxylic acids. In acetonitrile, the influence of added water on the reaction course is evidenced: increased reaction rate and acid yields, control of sulfuric acid formation. Intermediates such as sulfinic acid and thiosulfonate were detected and their rates of formation were monitored. The reaction appears to involve thiyl radicals giving rise to sulfonyl radicals in the presence of oxygen. A first tentative hypothesis concerning the mechanism is advanced.
- Robert-Banchereau, Evelyne,Lacombe, Sylvie,Ollivier, Jean
-
-
Read Online
- Poly(4-vinylpyridine) catalyzed selective methanolysis of methyl and methylene bromides
-
The effect of poly(4-vinylpyridine) (PVP) on the methanolysis of methyl bromide and methylene bromide was studied at temperatures between 75 °C and 125 °C. PVP acts as an efficient HBr scavenger promoting the formation of dimethyl ether (DME) and dimethox
- Prakash, G.K. Surya,Colmenares, Juan C.,Batamack, Patrice T.,Mathew, Thomas,Olah, George A.
-
-
Read Online
- Conversion of dimethyl ether to diesel fuel additives via dielectric barrier discharges
-
A high-efficient conversion of dimethyl ether (DME) to diesel fuel additives at ambient condition via dielectric-barrier discharges has been performed. The conversion of DME reaches a high value of 66.56% at a gas flow rate of 30 mL·min-1. The liquid obtained is a cetane number promoter of diesel fuels. The selectivity of liquid product is more than 40%.
- Jiang, Tao,Liu, Chang-Jun,Fan, Guo-Liang
-
-
Read Online
- Gas-phase carbonylation of methanol to dimethyl carbonate on chloride-free Cu-precipitated zeolite Y at normal pressure
-
Chloride-free Cu/zeolite Y catalysts with Cu loading of 2-14% were prepared by precipitation from aqueous copper(II) acetate solutions and inert activation with an Ar flow at 700-750 °C for 15 h. This inert activation resulted in a considerable activity of the catalyst for the oxidative carbonylation of methanol (MeOH) to dimethyl carbonate (DMC) under normal pressure at 140-160 °C at 10-12 wt% Cu loading. Space-time yields (STY) of DMC up to 100 gDMC l-1Cat h-1 were achieved with a feed composed of 36% MeOH, 48% CO, 6% O2, and balance He at a gaseous hourly space velocity (GHSV) of 3000 h-1. A threshold of copper loading (5-6 wt%) was found to exist before catalysts became active. This is associated with the preferential location of copper at ion-exchange positions of the zeolite structure Y not accessible for the reactants. After saturation of these sites, the placement of copper ions within the supercage led to active catalysts. Characterization of samples at various stages of preparation by N2 adsorption, XRD, XPS, ESR, 27Al-MAS-NMR, and TPR analysis revealed that the solid-state ion exchange during inert activation is accompanied by reduction of Cu2+ to Cu+. Copper ions exert a stabilizing effect on the crystallinity of the zeolite (in situ XRD, 27Al-MAS-NMR). No crystalline metallic copper, cuprous oxide, or cupric oxide were formed (XRD), but melting occurred at 750 °C for catalysts with 14% copper loading, resulting in the formation of a glassy amorphous copper silicate/aluminate phase. The latter effect can be prevented by applying lower activation temperatures. The catalysts were prepared without using chloride, and the reaction did not require co-feeding of HCl for maintaining activity, as is needed for CuCl/zeolite catalyst formulations.
- Richter,Fait,Eckelt,Schneider,Radnik,Heidemann,Fricke
-
-
Read Online
- Site Titration with Organic Bases During Catalysis: Selectivity Modifier and Structural Probe in Methanol Oxidation on Keggin Clusters
-
The selective and permanent titration of protons with organic bases (2,6-di-tertbutylpyridine or pyridine) provides an accurate measure of the dispersion of Keggin structures during catalytic oxidation of methanol. Titration allows the systematic control of the redox and acid properties of H3+nPVnMo12-nO40 (n=0-4) Keggin clusters and leads to unprecedented selectivity in the formation of dimethoxymethane (>80%) and high yields.
- Liu, Haichao,Bayat, Nader,Iglesia, Enrique
-
-
Read Online
- Benzophenone vs. Copper/Benzophenone in Light-Promoted Atom Transfer Radical Additions (ATRAs): Highly Effective Iodoperfluoroalkylation of Alkenes/Alkynes and Mechanistic Studies
-
Iodoperfluooralkylation of terminal alkenes and alkynes is effectively photo-promoted by benzophenone 2 (BP) or the photoreducible copper(II) complex 1. In particular, BP at 1 mol% in methanol upon 365 nm irradiation with a low-pressure mercury lamp (type TLC=thin layer chromatography, 6 W) results in a fast reaction with excellent reaction yields. Complex 1 and BP 2 exhibited very similar reactivity, suggesting that the reactions involving 1 are likely to be governed by the benzophenone photoactivation processes, rather than copper(I)/(II) redox processes. Mechanistic investigations using transient absorption spectroscopy revealed that a deactivation pathway of the benzophenone triplet (3BP*) is via its reaction with the methanol solvent. We propose that the generated radicals, in particular.CH2OH, play a key role in the initiation step forming Rf.by reacting with RfI, Rf.then entering a radical chain cycle.1H NMR studies provided evidence that a substantial amount (～7% NMR yield) of the hemiacetal CH3OCH2OH is formed, i.e., the possible by-product of the reaction between.CH2OH and RfI. Finally, DFT calculations indicate that a triplet-triplet energy transfer (TTET) process from3BP* to perfluorooctyl iodide (C8F17I) is unlikely or should be rather slow under the reaction conditions, consistent with the transient absorption studies. (Figure presented.).
- Beniazza, Redouane,Atkinson, Rachel,Absalon, Christelle,Castet, Frédéric,Denisov, Sergey A.,McClenaghan, Nathan D.,Lastécouères, Dominique,Vincent, Jean-Marc
-
-
Read Online
- Synthesis of methylal from methanol and formaldehyde catalyzed by Br?nsted acid ionic liquids with different alkyl groups
-
The catalytic reaction of methanol with formaldehyde for the preparation of methylal was investigated in various Br?nsted acid ionic liquids with different carbon chain length of alkyl groups. The structures, acidities, and properties of ionic liquids were experimentally characterized and theoretically analyzed. The Br?nsted acidity-viscosity-activity correlation for the ionic liquids was studied. Among all these ionic liquids, [C6ImBS][HSO4] exhibited the best catalytic performance, which was ascribed to its strong Br?nsted acidity and low viscosity. The catalytic activity of the ionic liquid was near that of concentrated sulfuric acid. The influences of ionic liquid dosage, reaction temperature and molar ratio of methanol to formaldehyde were explored using [C6ImBS]HSO4 as the catalyst. Under the optimal conditions of n(methanol):n(formaldehyde):n(ILs) = 2.5:1:0.0258, 60 °C, and 4 h, the conversion of formaldehyde can reach 63.37%. The ionic liquid [C6ImBS]HSO4 could be reused.
- Sun, Jiahan,Li, Hansheng,Song, Haoran,Wu, Qin,Zhao, Yun,Jiao, Qingze
-
-
Read Online
- VOx molecular level grafted g-C3N4 for highly selective oxidation of methanol to dimethoxymethane
-
A composite material VOx/g-C3N4 was prepared and its composition and structure was characterized by FT-IR, XRD, SEM, TEM and XPS. The results showed that VOx was grafted on g-C3N4 surface with molecularlevel dispersion via V or O atoms interacting with the characteristic groups on g-C3N4 surface. The highly dispersed VOx/g-C3N4 exhibited effectively catalytic activity and high selectivity for oxidation of methanol into methoxymethane (DMM), giving 44.9 mol/(molV·h) TOF and 95.2% selectivity of DMM. The dependence of catalytic activity on the surface properties and preparation procedure of the catalyst, reaction conditions and kinetics, and the stability of the catalyst were explored. Also, the in situ DRIFTS spectra of methanol adsorption on the VOx/g-C3N4 surface and effect of O2 on the adsorption, as well as the reaction mechanism were discussed.
- Ma, Hongrui,Wang, Hongxia,Lu, Bin,Zhao, Jingxiang,Cai, Qinghai
-
-
Read Online
- Greener synthesis of dimethyl carbonate from carbon dioxide and methanol using a tunable ionic liquid catalyst
-
Several types of ionic liquids (ILs) performance towards dimethyl carbonate (DMC) synthesis using cheap reactant (methanol) and waste CO2 which is abundantly available in the environment are discussed. We synthesized ILs with cheap raw materials such as ethylene glycol. The main aim of this study is to synthesize efficient catalysts for the production of profitable fuel additives. ILs show high thermal stability, less viscosity, and low vapor pressure. In addition, some ILs have high CO2 absorption capacity due to moderate acid-base properties. These ILs reversibly capture more CO2 which is more efficient towards mass transport of methanol at optimum reaction conditions which enhance the DMC yield. This catalytic system is easily reusable for several reactions without decreased performance under the same reaction conditions. These reaction conditions had an effect on the synthesis of DMC. Temperature, pressure, IL loading, and IL/DMAP ratio were fine tuned. We propose a mechanism which the reaction may follow. The synthesized ILs required moderate reaction conditions and reduce waste gases (CO2) from the environments as they have high CO2 absorption capacity compared to the metal oxide catalyst. Therefore, this catalytic system helps and gives new direction to synthesize new catalyst for other application.
- Pawar, Atul A.,Chaugule, Avinash A.,Kim, Hern
-
-
Read Online
- Sonochemical synthesis of vanadium complex nano-particles: a new precursor for preparation and evaluation of V2O5/Al2O3 nano-catalyst in selective oxidation of methanol to methylal
-
In this study, an ionic complex of V(V) was synthesized by using ultrasonic method, and it was used as a precursor for production of a new catalyst for selective preparation of methylal or dimethoxymethane (DMM). By reaction between an ionic ligand [pyda.H2]2+[pydc]2? (LH2), (pyda.H2?=?2,6-pyridine diammonium and pydc?=?2,6-pyridinedicarboxylate) and ammonium vanadate, the five coordinated V(V) complex, [pyda.H][V(pydc)O2], {2,6- diaminopyridinum 2,6-pyridinedicarboxylatodioxovanadate(V)}, VLH2 was synthesized. The prepared complex VLH2 was characterized by SEM, thermal analysis TGA/DTA, FT-IR spectroscopy and X-ray diffraction studies. The results showed that the yield of the reaction was increased up to 64%. The average particle sizes of the obtained complex VLH2 were about 50–60?nm. Also, the nano-catalyst of V2O5/Al2O3 was synthesized by impregnation method and was prepared as a nano-catalyst with average particles sizes of 50–60?nm, and its characterization was performed by XRD, EDX and SEM methods. Finally, the prepared catalyst was used to converting of methanol to methylal at different process conditions.
- Jamei, Mohammad Reza,Ranjbar, Maryam,Eliassi, Ali
-
-
Read Online
- 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)
-
- NHC-CDI Betaine Adducts and Their Cationic Derivatives as Catalyst Precursors for Dichloromethane Valorization
-
Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.
- Sánchez-Roa, David,Mosquera, Marta E. G.,Cámpora, Juan
-
p. 16725 - 16735
(2021/11/18)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- 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)
-
- SYNTHETIC METHOD AND SYNTHETIC SYSTEM
-
Provided is a synthesis method comprising a first step of producing a carbonate compound from carbon monoxide and an alcohol-based compound at an anode of a first electrochemical cell comprising a cathode and the anode, and a second step of synthesizing a first product by a dealcoholization reaction of the carbonate compound, wherein an alcohol-based compound eliminated in the second step is recycled in the first step.
- -
-
Paragraph 0252; 0255; 0271-0272
(2020/04/10)
-
- Novel synthesis method of alkoxymethylamine compound
-
The invention relates to a novel synthesis method of an alkoxymethylamine compound. The novel synthesis method comprises the steps: (1) dehydrating formaldehyde HCHO and alcohol R1OH by carrying out an aldolization under the action of an acid catalyst to obtain dialkoxymethane; and (2) carrying out a hydrocarbylation reaction on dialkoxymethane obtained in step (1) and substituted amine R2-NH2 toremove alcohol to obtain an alkoxymethyl substituent amine compound N-R1 oxymethyl-N-R2 amine. The synthesis method disclosed by the invention is simple in operation and high in yield reaching 92% orabove; and compared with the prior art, the novel synthesis method has the advantages that no acid wastewater, waste salts and chloromethyl alkyl ether serving as a cancerogen are greatly generated, the environment protection cost is favorably reduced, and the industrial prospect is higher.
- -
-
Paragraph 0034-0038
(2019/10/01)
-
- 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)
-
- Synthesis of dimethyl carbonate from CO2 and methanol over CeO2: Role of copper as dopant and the use of methyl trichloroacetate as dehydrating agent
-
The effect of copper as dopant on ceria (CeO2) was investigated in the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol. Ceria with different copper loadings (0.02 and 0.5 wt%) was synthesized using the dry impregnation method and characterized by H2-TPR, XRD, EPR, UV–VIS/DRS, acid-base properties and N2 physisorption. CeO2 with 0.02 wt% of Cu showed the highest catalytic activity and selectivity to DMC, mostly due to its basic sites, associated with the presence of oxygen vacancies. Higher Cu concentration (0.5 wt%) promotes dehydrogenation, favoring the formation of methyl formate as the main product. Pure CeO2 also produced dimethoxymethane as by-product. To circumvent the thermodynamic limitations of the reaction, methyl trichloroacetate was tested as dehydrating agent, showing superior performance than 2-cyanopyridine, due to its higher reactivity toward hydrolysis.
- Marciniak, Aryane A.,Alves, Odivaldo C.,Appel, Lucia G.,Mota, Claudio J.A.
-
-
- 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)
-
- Influence of Phase Composition of Bulk Tungsten Vanadium Oxides on the Aerobic Transformation of Methanol and Glycerol
-
A series of W–V–O catalysts with different m-WO3 and h-WO3 phase contents were hydrothermally synthesized by employing different tungsten, vanadium, and ammonium precursors and characterized by powder XRD, N2 adsorption, SEM, X-ray energy-dispersive spectroscopy, thermogravimetric analysis, Raman and FTIR spectroscopy, NH3 temperature programmed desorption, H2 temperature-programmed reduction, and XPS. Finally, the acid/redox properties were analyzed by using aerobic transformation of methanol as a characterization reaction. A correlation between phase composition as well as acid and redox properties was observed, which were correlated to the catalytic performance of the title materials in a one-pot oxydehydration reaction of glycerol. The hexagonal tungsten bronze (h-WO3) phase shows a significantly higher concentration of acid sites than monoclinic m-WO3, so that the acid properties of W–V–O oxides are directly related to the presence of h-WO3 crystals. The presence of a higher concentration of acid sites in V-containing h-WO3 crystals is a key factor to achieve high selectivity to both acrolein and acrylic acid during one-pot glycerol oxydehydration. Also, V sites in h-WO3 show higher selectivity in the consecutive reaction (partial oxidation of acrolein to acrylic acid), while V sites in the m-WO3 phase fundamentally lead to the formation of carbon oxides.
- Delgado, Daniel,Chieregato, Alessandro,Soriano, M. Dolores,Rodríguez-Aguado, Elena,Ruiz-Rodríguez, Lidia,Rodríguez-Castellón, Enrique,López Nieto, José M.
-
p. 1204 - 1211
(2018/03/22)
-
- Visible light-driven methanol dehydrogenation and conversion into 1,1-dimethoxymethane over a non-noble metal photocatalyst under acidic conditions
-
The dehydrogenation and conversion of methanol into 1,1-dimethoxymethane (DMM) was achieved over noble metal-free photocatalyst CdS/Ni2P under visible light. This photocatalytic process for methanol-to-H2 and DMM conversion is efficient and atom economic, with an optimal rate and selectivity of DMM of 188.42 mmol g-1 h-1 and 82.93%, respectively. This work supplies a new green approach for the direct efficient conversion of methanol into DMM and provides a promising avenue for sustainable bio-methanol applications.
- Chao, Yuguang,Lai, Jianping,Yang, Yong,Zhou, Peng,Zhang, Yelong,Mu, Zijie,Li, Shiying,Zheng, Jianfeng,Zhu, Zhenping,Tan, Yisheng
-
p. 3372 - 3378
(2018/07/13)
-
- Selective Oxidation of Methanol to Dimethoxymethane at Low Temperatures through Size-controlled VTiOx Nanoparticles
-
A vanadium/titanium mixed-oxide catalyst with a narrow particle-size distribution, large BET surface area, high dispersion of vanadium, and enhanced acidity and redox capabilities was prepared by a cetyltrimethylammonium bromide (CTAB) surfactant-associated vanadium oxide and titanium oxide co-precipitation route. The impact of the CTAB content on the catalyst properties, including structure, chemical states, and acidity and redox activities, was investigated by X-ray diffraction, BET surface area, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, H2 temperature-programmed reduction, and temperature-programmed desorption of ammonia. Relative to the catalyst prepared without CTAB, the resultant catalyst exhibited significantly improved low-temperature activity for the oxidation of methanol to dimethoxymethane (DMM). A maximum methanol conversion of 53 % with 93 % selectivity to DMM were achieved over the VTiS–CTAB catalyst at 120 °C, and this optimized reaction temperature is 25 °C lower than that needed for the reference catalysts and the yield of DMM is comparable.
- Sima, Rui,Liu, Guojuan,Wang, Qiyan,Wu, Ping,Qin, Tingting,Zeng, Gaofeng,Chen, Xinqing,Liu, Ziyu,Sun, Yuhan
-
p. 1776 - 1781
(2017/05/26)
-
- Photocatalytic Conversion of a FeCl3–CCl4–ROH System
-
The photocatalytic transformations of carbon tetrachloride and aliphatic primary alcohols in the presence of iron trichloride and a molar ratio of components FeCl3: CCl4: ROH = 1: 300: 2550 were studied. CCl4 is transformed into chloroform and hexachloroethane after exposure to a mercury lamp (250 W) to the FeCl3–CCl4–ROH system at 20°C, whereas the primary ROH alcohols are selectively oxidized into acetals (1,1-dialkoxyalkanes). The maximum conversion of CCl4 reaches 80%. The kinetics and mechanism of the photocatalytic conversion of the FeCl3–CCl4–ROH system are considered.
- Makhmutov
-
p. 695 - 700
(2018/03/08)
-
- Tailor-made Molecular Cobalt Catalyst System for the Selective Transformation of Carbon Dioxide to Dialkoxymethane Ethers
-
Herein a non-precious transition-metal catalyst system for the selective synthesis of dialkoxymethane ethers from carbon dioxide and molecular hydrogen is presented. The development of a tailored catalyst system based on cobalt salts in combination with selected Triphos ligands and acidic co-catalysts enabled a synthetic pathway, avoiding the oxidation of methanol to attain the formaldehyde level of the central CH2 unit. This unprecedented productivity based on the molecular cobalt catalyst is the first example of a non-precious transition-metal system for this transformation utilizing renewable carbon dioxide sources.
- Schieweck, Benjamin G.,Klankermayer, Jürgen
-
supporting information
p. 10854 - 10857
(2017/08/30)
-
- Method for Preparing Methyl Formate and Coproducing Dimethyl Ether
-
Method for preparing methyl formate and coproducing dimethyl ether by reacting a formaldehyde and methanol raw material (molar ratio range of 1:4 to 1:0.05) in a First Reaction Region at ranges from 50° C. to 100° C. with Catalyst A resulting in post-reaction material separated into Constituent I. Reacting Constituent I in a Second Reaction Region at ranges from 50° C. to 200° C. and from 0.1 MPa to 10 MPa with Catalyst B resulting in post-reaction material, which is separated into methyl formate, dimethyl ether and Constituent II. At least 1% of dimethyl ether is product, and recycling the rest to the First Reaction Region. Constituent II is recycled to the Second Reaction Region. Each component is gaseous phase and/or liquid phase, independently. The method shows long catalyst life, mild reaction condition, high utilization ratio of raw materials, continuous production and large scale industrial application potential.
- -
-
Paragraph 0046-0053
(2017/11/29)
-
- Active component of supported vanadium catalysts in the selective oxidation of methanol
-
The structure of catalysts based on vanadium oxide supported on different oxides (SiO2, γ-Al2O3, ZrO2, and TiO2) was investigated. Their catalytic properties in the selective oxidation of methanol in a temperature range of 100-250°C were studied. It was shown that the nature of the support determines the structure of the oxide forms of vanadium. The supporting of vanadium on SiO2 and γ-Al2O3 leads to the preferred formation of crystalline V2O5; the surface monomeric and polymeric forms of VOx are additionally formed on ZrO2 and TiO2. It was established that the crystalline V2O5 oxide is least active in the selective oxidation of methanol; the polymeric forms are more active than monomeric ones. The mechanism of the selective oxidation of methanol to dimethoxymethane and methyl formate on the vanadium oxide catalysts is considered.
- Kaichev,Popova,Chesalov,Saraev,Andrushkevich,Bukhtiyarov
-
-
- Dimethoxymethane preparation process
-
The present invention discloses a dimethoxymethane preparation process, wherein methanol and paraformaldehyde are adopted as raw materials, an acid is adopted as a catalyst, a reaction is performed in an organic solvent in an intermittent reaction manner under stirring to generate dimethoxymethane, and separation is performed to obtain the azeotrope of methanol and dimethoxymethane or the high-purity dimethoxymethane. According to the present invention, the preparation process has characteristics of rapid reaction and high conversion rate, and is suitable for the organic chemical industry field.
- -
-
Paragraph 0010
(2017/06/21)
-
- Method for recycling glyphosate byproduct dimethoxymethane
-
The invention provides a method for recycling glyphosate byproduct dimethoxymethane. The preparation process is as follows: placing well metered methanol, triethylamine and paraformaldehyde into a synthetic kettle, then adding glycine, performing an addition reaction, and slowly adding dimethyl phosphate; after the condensation reaction is ended, generating glyphosate byproduct dimethoxymethane; transferring materials into a rectifying still, and rectifying the glyphosate byproduct; condensing and recycling the gaseous dimethoxymethane generated after the rectification, primarily condensing high-content dimethoxymethane gas by adopting a primary conventional tubular condenser, enabling the condensed dimethoxymethane gas to enter a secondary conventional tubular condense, and condensing the dimethoxymethane gas; and recycling steam condensed water generated in the dimethoxymethane rectification process, and preheating dimethoxymethane mother liquor before entering a tower by utilizing the recycled condensed water of relatively high temperature. The method is stable in production, convenient in operation, capable of saving the production cost, economical and environment-friendly.
- -
-
Paragraph 0023-0030
(2017/07/08)
-
- Preparation of formaldehyde and a method of producing a acetal
-
The invention provides a method used for preparation of methyl aldehyde and co-production of methylal by oxidizing dimethyl ether. According to the method, raw material gas containing dimethyl ether and oxygen passes through a reactor filled with a double phase catalyst, and reaction is carried out at a reaction temperature of 250 to 400 DEG C, under a reaction pressure of 0.1 to 0.5MPa, and with gaseous hourly space velocity of 1000 to 10000/h so as to realize preparation of methyl aldehyde and co-production of methylal, wherein the double phase catalyst comprises a molybdenum and/or vanadium-based oxide catalyst I and a solid acid catalyst II, and the balance is inert gas which is used as a diluent gas; molar content of dimethyl ether accounts for 3 to 25% of that of the raw material gas, molar content of oxygen accounts for 10.0 to 40.0%.
- -
-
Paragraph 0067; 0068
(2017/04/26)
-
- Method for preparing methyl formate and coproducing dimethyl ether
-
The invention relates to a method for preparing methyl formate and coproducing dimethyl ether. The method comprises the steps: enabling raw materials, which contain formaldehyde and methanol, to enter a first reaction zone and be in contact with a catalyst A, carrying out separating so as to obtain a component I, enabling the component I to enter a second reaction zone and be in contact with a catalyst B, and then, carrying out separating so as to obtain methyl formate which serves as a product, dimethyl ether and a component II; taking at least 1% of the dimethyl ether as a product, and returning the rest dimethyl ether to the first reaction zone as circulating dimethyl ether; and returning the component II to the second reaction zone. In the raw materials, the ratio of the formaldehyde to the methanol (by mole numbers of carbon atoms contained by each ingredient) is 1: (0.05 to 4); the WHSV of the formaldehyde in the raw materials is 0.01/h to 15.0/h; the interior temperature of the first reaction zone is 50 DEG C to 100 DEG C; the interior temperature of the second reaction zone is 50 DEG C to 200 DEG C; the pressure is 0.1 to 10Mpa; and each ingredient is of a gas phase and/or a liquid phase independently. According to the method, the life of a catalyst is long, the reaction conditions are mild, the utilization ratio of the raw materials is high, and continuous production can be achieved, so that the method has large-scale industrialized application potential.
- -
-
Paragraph 0067; 0068
(2017/04/25)
-
- Ruthenium-Catalyzed Synthesis of Dialkoxymethane Ethers Utilizing Carbon Dioxide and Molecular Hydrogen
-
The synthesis of dimethoxymethane (DMM) by a multistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3resulted in a versatile catalytic system for the synthesis of various dialkoxymethane ethers. This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into a formaldehyde oxidation level, thus opening access to new molecular structures using this important C1source.
- Thenert, Katharina,Beydoun, Kassem,Wiesenthal, Jan,Leitner, Walter,Klankermayer, Jürgen
-
supporting information
p. 12266 - 12269
(2016/10/13)
-
- Effect of NH4+ exchange on CuY catalyst for oxidative carbonylation of methanol
-
NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY catalysts by a high temperature anhydrous interaction between the support and copper (II) acetylacetonate Cu(acac)2. The catalysts were used for the oxidative carbonylation of methanol to dimethyl carbonate (DMC) at atmospheric pressure. The textural and acidic properties of NaNH4Y zeolite and the CuY catalysts were investigated by X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption, temperature programmed reduction of H2, X-ray photoelectron spectroscopy and temperature programmed desorption of NH3. With increasing NH4NO3 concentration, the NH4+ exchange degree increased while the crystallinity of the zeolite remained intact. Crystalline CuO was formed when the NH4+ exchange degree of NaNH4Y was low, and the corresponding CuY catalyst showed low catalytic activity. With increasing of the NH4+ exchange degree of NaNH4Y, the content of surface bound Cu+ active centers increased and the catalytic activity of the corresponding CuY catalyst also increased. The surface bound Cu+ content reached its maximum when the NH4+ exchange degree of NaNH4Y reached towards saturation. The CuY exhibited optimal catalytic activity with 267.3 mg/(g·h) space time yield of DMC, 6.9% conversion of methanol, 68.5% selectivity of DMC.
- Wang, Yuchun,Zheng, Huayan,Li, Zhong
-
p. 1403 - 1412
(2016/09/07)
-
- A method of preparing formic acid methyl ester (by machine translation)
-
The present application relates to a method of preparing formic acid methyl ester. Contain formaldehyde, methanol and/or dimethyl ether of the raw materials into the reaction zone and catalyst 1st A contact and separation, I get component 2nd B into contact with the catalyst after the reaction, the product is separated as methyl formate, dimethyl ether reaction zone to return to 1st, 2nd reaction zone II to return components; formaldehyde in the raw material, methanol and/or dimethyl ether to the proportion of the carbon atoms of each component lives of mole, to formaldehyde: methanol and/or dimethyl ether = 1:2-4 ; raw materials the quality of the formaldehyde in the airspeed is 0.01-15.0h -1; the temperature in the reaction zone the 1st 50-100 °C; 2nd the temperature in the reaction zone for 50-200 °C; pressure is 0.1-10 MPa; independently for each component of the gas phase and/or liquid phase. Long service life of the catalyst in this application, the mild reaction conditions, utilization rate of raw materials is high, capable of continuous production, with large-scale industrial application potential. (by machine translation)
- -
-
Paragraph 0060; 0061; 0065; 0066; 0074
(2017/01/17)
-
- Highly Active Subnanometer Au Particles Supported on TiO2 for Photocatalytic Hydrogen Evolution from a Well-Defined Organogold Precursor, [Au5(mesityl)5]
-
A highly efficient H2 evolution photocatalyst based on TiO2 supported subnanometer Au particles was developed on the basis of the reaction of a gold(I) molecular precursor [Au5Mes5] (Mes = 2,4,6-trimethylphenyl), with titanium dioxide partially dehydroxylated at 120 °C. IR, UV-vis, elemental analysis, XANES, and STEM-EDX show that the deposition of [Au5Mes5] onto TiO2 leads to the formation of both subnanometer Au particles and chemisorbed [Au5Mes5]. The remaining organic ligands are removed via a mild treatment under H2, yielding subnanometer gold(0) particles. A range of Au loadings (0.3, 0.9, 2.4 wt %) with similar particle sizes (2 are obtained and tested in methanol-assisted photocatalytic hydrogen production under UV light. These catalysts display significantly higher activity than a commercial reference Au-TiO2 catalyst. The presence of chemisorbed [Au5Mes5] in the as-synthesized catalyst further improved activity, albeit at the expense of stability. This work demonstrates a simple synthetic route to obtain subnanometer Au particles on TiO2 that display exceptional activity in photocatalysis.
- Siddiqi, Georges,Mougel, Victor,Copéret, Christophe
-
supporting information
p. 4026 - 4033
(2016/05/19)
-
- Efficient V2O5/TiO2 composite catalysts for dimethoxymethane synthesis from methanol selective oxidation
-
A series of V2O5/TiO2 composite catalysts (V2O5-TiO2-Al2O3, V2O5-TiO2-SiO2, V2O5-TiO2-Ce2O3 and V2O5-TiO2-ZrO2) were prepared by an improved rapid sol-gel method and the catalytic behavior for dimethoxymethane (DMM) synthesized from methanol selective oxidation was investigated. The physicochemical properties of catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller isotherms (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), NH3 temperature programmed desorption (NH3-TPD), infrared spectroscopy of adsorbed pyridine (Py-IR) and transmission electron microscopy (TEM) techniques. The best catalytic performance was obtained on a V2O5-TiO2-SiO2 catalyst with methanol conversion of 51% and DMM selectivity of 99% at 413 K. Furthermore, the V2O5-TiO2-SiO2 catalyst displayed an excellent catalytic stability within 240 h. Results showed that more Bronsted acidic sites were critical to increasing the DMM yield. The activity of V2O5/TiO2 composite catalysts decreased with increasing Bronsted acidity, but the yield of DMM increased with an increasing amount of Bronsted acidic sites. The excellent performance of the V2O5-TiO2-SiO2 catalyst might come from its optimal acidity and redox properties, higher active surface oxygen species, together with more Bronsted acid sites.
- Fan, Zhihong,Guo, Heqin,Fang, Kegong,Sun, Yuhan
-
p. 24795 - 24802
(2015/03/18)
-
- 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
-
-
- The one-step oxidation of methanol to dimethoxymethane over sulfated vanadia-titania catalysts: Influence of calcination temperature
-
Sulfated vanadia-titania catalysts were prepared by the rapid combustion method and calcined at different temperatures. The influence of calcination temperature on the physicochemical properties of the catalysts was characterized by nitrogen adsorption (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H2-TPR-MS), thermogravimetry (TG) and temperature programmed desorption of ammonia (NH3-TPD) techniques. The catalytic activities were evaluated by the partial oxidation of methanol to dimethoxymethane (DMM). The results showed that vanadia and sulfate were highly dispersed as the catalysts were calcined at 723 and 773 K. The reducibility of the highly dispersed vanadia was stronger than the aggregated vanadia. And the larger number of acidic sites was related to the higher dispersion of sulfate. Moreover, the higher dispersion of vanadia contributed to higher methanol conversion, and the stronger reducibility combined with the larger number of acidic sites led to high DMM selectivity. As a result, the catalysts calcined at 723 and 773 K presented higher methanol conversion and DMM selectivity than those calcined at 673 K or above 823 K.
- Guo, Heqin,Li, Debao,Chen, Congbiao,Jia, Litao,Hou, Bo
-
p. 64202 - 64207
(2015/08/18)
-
- Reaction system and process for preparing polymethoxy dimethyl ether
-
The invention relates to a reaction system and process for continuously preparing polymethoxy dimethyl ether (DMM3-8) by a continuous acetalization reaction between an aqueous formaldehyde solution or paraformaldehyde and methanol in the presence of a functionalized acidic ionic liquid as a catalyst. The reaction system of the invention preferably comprises a formaldehyde-concentrating unit, a vacuum-drying unit, an acetalization reaction unit, a product-separating unit and a catalyst-regenerating unit. The process of the invention uses aqueous formaldehyde solution as an initial raw material, which is concentrated in the formaldehyde-concentrating unit to a concentrated formaldehyde of 50～80 wt.%, and vacuum-dried to paraformaldehyde, or uses paraformaldehyde as raw material directly, then obtains DMM3-8 by an acetalization reaction. The raw materials of the reaction used in the invention are cheap and available easily, and the utilization rate of formaldehyde is high; an efficient separation between the catalyst and product, as well as the reuse of the catalyst and raw materials, are realized by a separation mode of combining extraction and rectification together.
- -
-
Paragraph 0082; 0083
(2015/04/15)
-
- 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
(2015/12/11)
-
- Conversion of dimethyl ether to toluene under an O2 stream over W/HZSM-5 catalysts
-
The direct conversion of dimethyl ether (DME) to toluene without other aromatics is realized over W/HZSM-5 catalysts with high W contents. The influence of W content on the nature of tungsten species, the distribution of acid sites, the redox properties, and the subsequent catalytic performance of W/HZSM-5 in DME conversion was investigated. The introduction of a high content of W in HZSM-5 can bring about some new redox sites and acidic sites associated with W species, although they also cover some acidic sites in HZSM-5. In this way, the introduction of W interrupts the dual cycle of the DME-to-hydrocarbon reaction on HZSM-5, and effectively the formation of higher methylbenzenes is limited.
- Wang, Bo,Wang, Hui,Liu, Guangbo,Li, Xuemin,Wu, Jinhu
-
p. 1813 - 1820
(2015/04/27)
-
- REACTION SYSTEM AND PROCESS FOR PREPARING POLYMETHOXY DIMETHYL ETHER
-
The invention relates to a reaction system and process for continuously preparing polymethoxy dimethyl ether (DMM3-8) by a continuous acetalization reaction between an aqueous formaldehyde solution or paraformaldehyde and methanol in the presen
- -
-
Paragraph 0105-0108
(2015/04/15)
-
- The Synthesis of Dimethyl Carbonate by the Oxicarbonylation of Methanol Over Cu Supported on Carbon Norit
-
The catalytic activity of Norit supported Cu, Ni and Cu-Ni catalysts was investigated in the synthesis of dimethyl carbonate (DMC) by the oxidative carbonylation of methanol. Cu/Norit showed the best catalytic activity. The reaction was carried out in a continuous flow system at atmospheric pressure usually at 393 K. The main products were methyl formate, DMC and CO2. The methanol conversion on Cu/Norit achieved in steady state was about 22 % and the DMC yield 13.2 %. 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+. It is possible that the DMC formation rate depends on the surface concentration of oxidized Cu and on the ratio of Cu+ and Cu2+. Based upon the IR measurements adsorbed DMC was found on the surface of the Cu/Norit catalyst during the catalytic reaction.
- Merza,Lszl,Oszk,Ptri,Varga,Erdohelyi
-
p. 881 - 892
(2015/08/06)
-
