Decomposition Of Methyl Formate Research Articles

Highly Efficient Catalyst for Methyl Formate Decomposition Through KOH Activation of Carbon Material Supports

AbstractIn this research, we utilized potassium hydroxide (KOH) to re‐activate activated carbon and subsequently loaded zinc oxide to obtain a more efficient catalyst for the decomposition of methyl formate. The objective of KOH activation was to augment the catalytic activity of the original ZnO/AC catalyst. Various techniques were used to characterize the prepared catalyst samples, including BET, FT‐IR, SEM, XRD, XPS, and CO2‐TPD. We found that KOH re‐activation of AC can increase the carrier's specific surface area and alkaline sites, significantly improving the catalyst's performance.

An efficient ZnO/AC catalyst for selective decomposition of methyl formate to methanol and CO

An efficient ZnO/AC catalyst for selective decomposition of methyl formate to methanol and CO

Comparing the pyrolysis kinetics of dimethoxymethane and 1,2-dimethoxyethane: An experimental and kinetic modeling study

This work investigates the reaction kinetics of the thermal decomposition of dimethoxymethane (DMM) and 1,2-dimethoxyethane (1,2-DME), which are both representative molecules of the promising clean polyether fuels. Pyrolysis experiments are carried out with helium diluted mixtures containing individual fuels in a flow tube at two different pressures of 760 Torr and 30 Torr. By varying the temperature distributions along the flow tube, the resulting species composition is sampled downstream the reactor and analyzed by a photoionization mass spectrometer. A kinetic model, including sub-mechanisms for the thermal decomposition of both fuels, is proposed, which can well characterize important measurements, such as the fuel decomposition reactivity and the speciation of crucial products. Under identical conditions, 1,2-DME exhibits a higher decomposition reactivity than DMM, because of the characteristic C–C bond fission as well as the easier hydrogen abstraction reactions by methyl radical. Some fuel-specific intermediates are observed, including methyl formate in DMM pyrolysis, methyl vinyl ether and methoxy acetaldehyde in 1,2-DME pyrolysis. These species mainly come from fuel radical dissociations following the hydrogen abstractions from the central (–CH2O–) and (–CH2CH2O–) moieties in DMM and 1,2-DME, respectively. The formation of some other intermediates are closely related to the consumption of these fuel-specific species. Particularly, the decomposition of methyl formate produces high concentrations of methanol in DMM pyrolysis. In 1,2-DME pyrolysis, the consumption of methyl vinyl ether and methoxy acetaldehyde brings about the formation of C2 oxygenated intermediates such as acetaldehyde, ethenol and ketene. Higher concentrations of unsaturated C2 (ethylene and acetylene) and larger hydrocarbon intermediates present in 1,2-DME pyrolysis, due to the existence of C–C bond in the fuel molecule.

High‐Performance RuCl3 Catalyst Systems for Hydro‐Esterification of Methyl Formate and Ethylene

Summary of main observation and conclusionRuCl3 catalyst system has many advantages for the hydro‐esterification of methyl formate and ethylene to methyl propionate. However, the unsatisfied performance restricts the development of this route. In this work, high‐performance RuCl3 catalyst systems (RuCl3‐[PPN]Cl‐Et4NI and RuCl3‐NaI) are firstly reported for this reaction. In RuCl3‐[PPN]Cl‐Et4NI catalyst system, the conversion of methyl formate and the selectivity to methyl propionate are 93.9% and 90.9% at mild reaction conditions (165°C, 2.5 MPa), respectively. Noticeably, a simple inorganic RuCl3‐NaI catalyst system achieves 88.8% conversion of methyl formate and 97.6% selectivity to methyl propionate (86.7% yield) at same conditions. NaI, as a promoter, may inhibit the decomposition of methyl formate and be conducive to the formation of methyl propionate. The effects of solvents and promoters are investigated in detail. In addition, the reaction mechanism has been also analyzed. It is hoped to lay a certain foundation for further industrial application.

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

Catalytic Decomposition of Methyl Formate in the Presence of Transition Metal Complexes, Phosphine Ligands and Water

Theoretical predictions on dehydrogenation of methanol over copper-silica catalyst in a membrane reactor

Dehydrogenation of methanol was performed over copper-silica catalyst. Methyl formate decomposition to carbon monoxide and hydrogen was considered as a main side reaction. Tubular and membrane reactors were compared theoretically in terms of efficiency of the process. For this purpose, a two-dimensional non-isothermal stationary mathematical model of the catalytic membrane reactor was developed and applied. The reaction of methanol dehydrogenation (in a tube side) was conjugated with hydrogen oxidation reaction (in a shell side). Conjugation of the processes was found to increase the methanol conversion up to 87% and achieve the methyl formate yield as high as 80% at 125°C. The impact of various parameters on the process characteristics was studied using the developed mathematical model.

Kinetic studies of methanol dehydrogenation. Part III: carbon-supported copper catalysts

The kinetics of methanol dehydrogenation over carbon-supported copper catalyst was studied. The catalyst was prepared by the incipient wetness impregnation of carbonaceous graphite-like material Sibunit with aqueous solution of copper nitrate. The resulting Cu/C samples were calcined and reduced in a hydrogen flow within temperature interval of 200–400 °C. Experiments were carried out in a flow-through fixed-bed tubular reactor. Observable rate constants were determined for the reactions of methanol dehydrogenation to methyl formate and methyl formate decomposition on carbon monoxide and hydrogen. The process of methanol dehydrogenation in a tubular reactor was simulated by means of mathematical modeling. The estimation of kinetic parameters in accordance with experimental data obtained for the Cu/C sample reduced at 300 °C has allowed us to consider the reversibility of methanol dehydrogenation reaction.

Kinetic studies of methanol dehydrogenation. Part II: copper on silica–montmorillonite composite

The kinetics of methanol dehydrogenation over copper catalyst supported on silica–montmorillonite composite was studied. The samples of the catalyst were prepared by incipient wetness impregnation followed by drying, calcination and reduction in hydrogen flow in a temperature range 200–400 °C. Kinetic studies were performed in a flow fixed-bed reactor. Observed rate constants were determined for the reactions of methanol dehydrogenation into methyl formate and methyl formate decomposition on carbon monoxide and hydrogen. An increase in the reduction temperature was shown to have no significant effect on the catalytic properties. Numerical methods were used to calculate the kinetic constants with consideration of reversibility of methanol dehydrogenation reaction the sample reduced at 300 °C.

Decomposition of Methyl Formate over Supported Pd Catalysts

Methyl formate (MF) is used as alternative carbonylating agent in many organic transformations. The current study investigates nature of decomposition of MF over Pd catalysts on different support of varying physicochemical properties. Palladium catalysts with 1 and 5 wt% supported on Mg, and 5 wt% on γ-Al2O3 and α-Al2O3 were synthesized by wetness impregnation and their catalytic activities for MF decomposition were examined. MgO supported Pd with 1 wt% showed maximum MF conversion of about 40 mol% and produced predominantly carbon monoxide (CO) and methanol (MeOH) in the molar ratio of 1:1.2 at 150 °C, 1 atm. However, 5 wt% Pd/MgO catalysts showed decrease in the MF conversion to 33 mol% producing CO/MeOH in the ratio of 1:1. Catalysts with 5 wt% Pd supported on γ-Al2O3 and α-Al2O3 showed lower MF conversion compared to the Pd supported on MgO. Dimethyl ether (DME) was produced as the main by-product on Pd/γ-Al2O3 apart from CO and MeOH and it is attributed to dehydration of methanol on the acidic sites of the support. Higher MF conversion on Pd/MgO catalysts is mainly attributed to the support-metal interactions which are significant in case of Pd–MgO in addition to higher Pd dispersion with 1 wt% Pd on MgO. These results suggest that the presence of Pd over basic supports can be used to produce CO at lower temperatures; hence they may be used as a source of CO for carbonylation reactions at low pressures.

Kinetic studies of methanol dehydrogenation. Part I: copper-silica catalysts

A series of Cu/SiO2 catalysts was prepared using incipient wetness impregnation of silica gel with an aqueous solution of copper nitrate. The copper loading was 5 wt%. After the calcination, the catalyst was reduced in a hydrogen flow at varied temperatures (200, 300, and 400 °C). A conventional fixed bed reactor system was used to study the kinetics of methanol dehydrogenation to methyl formate. Methyl formate decomposition to carbon monoxide and hydrogen was taken into account as a main side reaction. Observable rate constants were determined. The temperature of reductive pretreatment of the catalysts was shown to affect strongly their catalytic behavior in the studied reaction. The highest methyl formate yield was achieved for the sample reduced at 200 °C. An increase of reduction temperature up to 400 °C worsens the selectivity towards the main product in approximately by a factor of 2. The kinetic parameters obtained were used for modelling the process in a tubular reactor. Good agreement of theoretical and experimental data was found.

Gas-phase carbonylation of dimethoxymethane to methyl methoxyacetate over the Cs2.5H0.5PW12O40 catalyst

It has been shown that cesium hydrogen phosphotungstate Cs2.5H0.5PW12O40 is a promising catalyst of the gas-phase carbonylation of dimethoxymethane (DMM) to methyl methoxyacetate (MMA). This catalyst provided the MMA selectivity and yield of 54% and 40%, respectively, under mild experimental conditions: T = 110°C, P = 10 bar, and GHSV = 6000 h–1 for DMM/CO/Ar = 4/76/20 mol/mol/mol. The carbonylation of DMM to MMA is accompanied by side reactions of DMM disproportionation into dimethyl ether (DME) and methyl formate (MF), as well as by secondary side reactions of MF decomposition into methanol and CO and methanol dehydration into DME.

Photocatalytic Decomposition of Methyl Formate over TiO2-Supported Pt Metals

The photoinduced vapor-phase decomposition of methyl formate was investigated on pure and on Pt-metals-promoted TiO2. Infrared spectroscopic studies revealed that illumination induced the dissociation of molecularly adsorbed methyl formate to formate on pure TiO2 even at ∼186 K. This process is indicated by the appearance of the absorption band at 1580–1590 cm–1 due to asymmetric stretch of formate species. The extent of the dissociation is increased with the time of irradiation. Deposition of Pt metals on TiO2 only slightly influenced this process. The photocatalytic decomposition of methyl formate vapor on pure TiO2 occurred to only a limited extent at 300 K, but the deposition of Pt metals on TiO2 appreciably enhanced the extent and the rate of photodecomposition. Nevertheless the photocatalytic reaction of methyl formate proceeded more slowly compared to that of formic acid on the same catalysts, and produced more CO. Addition of H2O to the methyl formate decreased the CO/H2 ratio by a factor of 4. Wh...

Photocatalytic decomposition of formic acid and methyl formate on TiO2 doped with N and promoted with Au. Production of H2

Abstract The photo-induced vapor-phase decompositions of formic acid and methyl formate were investigated on pure, N-doped and Au-promoted TiO 2 . Infrared (IR) spectroscopic studies revealed that illumination initiated the decomposition of adsorbed formate formed in the dissociation of formic acid and located mainly on TiO 2 . The photocatalytic decompositions of formic acid and methyl formate vapor on pure TiO 2 occurred to only a limited extent. The deposition of Au on pure or doped TiO 2 markedly enhanced the extent of photocatalytic decomposition of formic acid. The main process was dehydrogenation to give H 2 and CO 2 . The formation of CO occurred to only a very small extent. Addition of O 2 or H 2 O to the formic acid decreased the CO level from ∼0.8% to ∼0.088%. Similar features were experienced in the photocatalytic decomposition of methyl formate, which dissociated in part to give surface formate. Experiments over Au deposited on N-doped TiO 2 revealed that the photo-induced decomposition of both compounds occurs even in visible light.

High temperature rate constants for H/D + methyl formate and methyl acetate

The reactions of D/H with methyl formate (MF) and methyl acetate (MA) have been studied with both shock-tube experiments and ab initio transition state theoretical calculations. D-atom profiles were measured behind reflected shock waves using D-atom atomic resonance absorption spectrometry (ARAS) over the temperature range 1050–1270K, at pressures ≅0.5atm.The title reactions have been theoretically studied at the CCSD(T)/cc-pv∞z//MP2/aug-cc-pvtz and CCSD(T)/cc-pv∞z//B3LYP/6-311++G(d,p) levels of theory. Theoretical calculations suggest the dominance of the abstraction processes in comparison to addition processes in the 300–2000K T-range. Over the T-range of the present experiments, the theoretically predicted isotope effects, kD/kH, are near unity.D-atom depletion in the present experiments is sensitive only to the reactions,(A)D+CH3OC(O)H→products(B)D+CH3OC(O)CH3→productsSimulations of the measured D-atom profiles allow for determinations of total rate constants for the processes (A) and (B). In combination with results obtained from recent H-ARAS experiments from our laboratory on MF decomposition, total experimental rate constants kA can be described by the Arrhenius equation,kA=(4.47±1.54)×10-10exp(-5843±416K/T)cm3molecule-1s-1(1050–1270K)For H/D+MF, total experimental rate constants, kA, and branching ratios agree well with theoretical predictions.For D/H+MA, total rate constants predicted by theory are in reasonable agreement with the experimental data. The theoretical predictions are preferred for use, with kB represented by the modified Arrhenius equation,kB=3.078×10-19T2.78exp(-3261K/T)cm3molecule-1s-1(500–2000K)To our knowledge, the present experiments are the first direct measurements for the title reactions and the rate constants from this combined experimental/theoretical effort are recommended for use in combustion modeling.

Shock tube/laser absorption studies of the decomposition of methyl formate

Reaction rate coefficients for the major high-temperature methyl formate (MF, CH3OCHO) decomposition pathways, MF→CH3OH+CO (1), MF→CH2O+CH2O (2), and MF→CH4+CO2 (3), were directly measured in a shock tube using laser absorption of CO (4.6μm), CH2O (306nm) and CH4 (3.4μm). Experimental conditions ranged from 1202 to 1607K and 1.36 to 1.72atm, with mixtures varying in initial fuel concentration from 0.1% to 3% MF diluted in argon. The decomposition rate coefficients were determined by monitoring the formation rate of each target species immediately behind the reflected shock waves and modeling the species time-histories with a detailed kinetic mechanism [12]. The three measured rate coefficients can be well-described using two-parameter Arrhenius expressions over the temperature range in the present study: k1=1.1×1013exp(−29556/T, K)s−1, k2=2.6×1012exp(−32052/T, K)s−1, and k3=4.4×1011exp(−29 078/T, K)s−1, all thought to be near their high-pressure limits. Uncertainties in the k1, k2 and k3 measurements were estimated to be ±25%, ±35%, and ±40%, respectively. We believe that these are the first direct high-temperature rate measurements for MF decomposition and all are in excellent agreement with the Dooley et al. [12] mechanism. In addition, by also monitoring methanol (CH3OH) and MF concentration histories using a tunable CO2 gas laser operating at 9.67 and 9.23μm, respectively, all the major oxygen-carrying molecules were quantitatively detected in the reaction system. An oxygen balance analysis during MF decomposition shows that the multi-wavelength laser absorption strategy used in this study was able to track more than 97% of the initial oxygen atoms in the fuel.

Methanol conversion over CuO supported on CeO2-ZrO2: An in situ IR spectroscopic study

The main reactions yielding hydrogen are the recombination of hydrogen atoms on copper clusters and methyl formate decomposition. Methyl formate results from the interaction between the linear methoxy group and the formate complex located on CuO. The source of CO2 appearing in the gas phase is the formate complex, and the source of CO is methyl formate. The rates of methoxy group conversion and product formation over supports (ZrO2, CeO2, Ce0.8Zr0.2O2) and copper-containing catalysts (5%Cu/CeO2, 5%Cu/ZrO2, 2%Cu/Ce0.8Zr0.2O2, 2%Cu/Ce0.1Y0.1Zr0.8) are compared. The dominant process in methoxy group conversion over the supports and copper-containing catalysts is methanol decomposition to H2 and CO and to H2 and CO2, respectively. The methoxy group conversion rate is proportional to the H2 and CO2 formation rate and is determined by the concentration of supported copper.

An experimental and kinetic modeling study of methyl formate low-pressure flames

The oxidation of methyl formate (CH 3OCHO), the simplest methyl ester, is studied in a series of burner-stabilized laminar flames at pressures of 22–30 Torr and equivalence ratios ( Φ) from 1.0 to 1.8 for flame conditions of 25–35% fuel. Flame structures are determined by quantitative measurements of species mole fractions with flame-sampling molecular-beam synchrotron photoionization mass spectrometry (PIMS). Methyl formate is observed to be converted to methanol, formaldehyde and methane as major intermediate species of mechanistic relevance. Smaller amounts of ethylene and acetylene are also formed from methyl formate oxidation. Reactant, product and major intermediate species profiles are in good agreement with the computations of a recently developed kinetic model for methyl formate oxidation [S. Dooley, M.P. Burke, M. Chaos, Y. Stein, F.L. Dryer, V.P. Zhukov, O. Finch, J.M. Simmie, H.J. Curran, Int. J. Chem. Kinet. 42 (2010) 527–529] which shows that hydrogen abstraction reactions dominate fuel consumption under the tested flame conditions. Radical–radical reactions are shown to be significant in the formation of a number of small concentration intermediates, including the production of ethyl formate (C 2H 5OCHO), the subsequent decomposition of which is the major source of observed ethylene concentrations. The good agreement of model computations with this set of experimental data provides a further test of the predictive capabilities of the proposed mechanism of methyl formate oxidation. Other salient issues in the development of this model are discussed, including recent controversy regarding the methyl formate decomposition mechanism, and uncertainties in the experimental measurement and modeling of low-pressure flame-sampling experiments. Kinetic model computations show that worst-case disturbances to the measured temperature field, which may be caused by the insertion of the sampling cone into the flame, do not alter mechanistic conclusions provided by the kinetic model. However, such perturbations are shown to be responsible for disparities in species location between measurement and computation.

Mechanism of methanol conversion on ZrO2 and 5% Cu/ZrO2 according to in situ IR spectroscopic data

It is demonstrated by in situ IR spectroscopy that, in methanol conversion on ZrO2 and 5% Cu/ZrO2 catalysts, methoxy groups are present on the catalyst surface, which result from O-H or C-O bond breaking in the methanol molecule. Two types of formate complexes, localized on ZrO2 and CuO, are also observed. The formate complexes form via the oxidative conversion of the methoxy groups. There are two types of linear methoxy groups. First-type linear methoxy groups condense with the formate complex located on CuO to yield methyl formate and then CO and H2. Second-type methoxy groups appear as intermediate products in the formation of dimethyl ether. The main hydrogen formation reactions are the recombination of hydrogen atoms (which result from the interconversion of surface complexes) on copper clusters and the decomposition of methyl formate. The source of CO2 in the gas phase is the formate complex, and the source of CO is methyl formate. The effect of water vapor and oxygen the surface reactions and product formation is discussed.

Ab Initio Chemical Kinetics of Methyl Formate Decomposition: The Simplest Model Biodiesel

The energetics and kinetics of methyl formate decomposition have been investigated by high-level ab initio calculations with rate constant predictions. The paucity of reliable experimental data for methyl formate has been circumvented by studying a very similar system, namely, the decarboxylation of acetic acid, in order to help validate the theoretical calculations. Our study shows that methyl formate decomposes to methanol and carbon monoxide, almost exclusively, with a high pressure limit rate constant of k(1)(infinity) = 2.128 x 10(12)T(0.735) exp(-34,535/T) s(-1), and the decomposition of acetic acid to methane and carbon dioxide proceeds with a rate constant, k(4)(infinity), of 1.668 x 10(10)T(1.079) exp -35,541/T s(-1). Experimental values for the formation enthalpy of methyl formate are discussed, and it is shown that these can be reconciled with our computed value for DeltaH(f) (298.15 K) of -360.1 +/- 2.2 kJ mol(-1). In turn, bond dissociation energies for all single bonds in the molecule are presented.

Properties of surface compounds in methanol conversion on copper-containing catalysts based on CeO2 according to in situ IR-spectroscopic data

Formate and carbonate complexes and bridging and linear methoxy groups were detected on the surfaces of CeO2 and 5.0% Cu/CeO2 under the reaction conditions of methanol conversion using IR spectroscopy. The reaction products were H2, methyl formate, CO, CO2, and H2O. The bridging and linear methoxy groups were the sources of formation of bi- and monodentate formate complexes, respectively. Methyl formate was formed as a result of the interaction of the linear methoxy group and the formate complex. The study demonstrated that the recombination of hydrogen atoms on copper clusters and the decomposition of methyl formate were the main reactions of hydrogen formation. Formate and carbonate complexes were the source of CO2 formation in the gas phase, and the decomposition of methyl formate was the source of CO. It was found that the addition of water vapor to the reaction flow considerably decreased the rate of CO formation at a constant yield of hydrogen. The effects of water vapor and oxygen on the course of surface reactions and the formation of products are discussed. To explain the mechanism of methanol conversion, a scheme of surface reactions is proposed.