Reaction Of CH3OH Research Articles

Density-functional theory study of the reaction pathway for methanol demethanation on [formula omitted] ( n = 3,4)

Minimum-energy pathways for the demethanation reaction CH 3OH + Ni n + ( n = 3,4)→Ni n O + + CH 4 have been computed to examine why this reaction occurs preferentially on Ni 4 + . Stationary points of paths for the demethanation of CH 3OH on Ni n + ( n = 3,4), which provide possible reaction pathways, were characterized and the associated activation barriers were evaluated on both Ni 3 + and Ni 4 + via density-functional theory calculations. On Ni 4 + , all the transition states along the minimum-energy path are energetically below the reactant asymptote, whereas on Ni 3 + , the transition states are above it.

The mechanism of methanol decomposition by CuO. A theoretical study based on the reaction force and reaction electronic flux analysis

A theoretical study of methanol decomposition using a model representing the initial step of the reaction CH₃OH + CuO → CH₂O + H₂O + Cu is presented. Theoretical calculations using B3LYP/6-31 G along with Lanl2DZ pseudopotentials on metallic centers were performed and the results discussed within the framework of the reaction force analysis. It has been found that the reaction takes place following a stepwise mechanism: first, copper reduction (Cu⁺² → Cu⁺) accompanies the oxygen transposition and then a second reduction takes place (Cu⁺ → Cu₀) together with a proton transfer that produce formaldehyde and release a water molecule.

Theoretical calculations of structures, energetics, and kinetics of O (3P) + CH3OH reactions

AbstractDFT methods are used in calculations of geometries, energies, and frequencies for O (3P) + CH3OH reactions. CCSD(T) single‐point calculations are carried out followed by extrapolation to the complete basis set (CBS) limit and inclusion of core correlation. The best estimate results of the reaction enthalpies (ΔH) for the first (−7.1 kcal/mol), second (2.0 kcal/mol), and the third (25.8 kcal/mol) reactions path are in excellent agreement with the experimental values, i.e., −7.2 ± 0.2, 1.2 ± 1.0, and 26.0 ± 1.2 kcal/mol, respectively. Rate constants and activation energies in the range of 300–2,000 K calculated with the variational transition state theory are in good agreement with previous studies. H/D and 12C/13C kinetic isotope effects are also calculated in good agreement with available experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010

Photochemistry of carbon monoxide and methanol in water and nitric acid hydrate ices: A NEXAFS study

Soft X-ray induced chemistry of H(2)O, CO and CH(3)OH and the effects of the water and nitric acid hydrate (HNO(3).1.65H(2)O) matrix on the photochemistry of CO and CH(3)OH have been investigated using NEXAFS spectroscopy. For pure H(2)O, CO and CH(3)OH ices, we show that the destruction rates are strongly limited by back reactions, leading to strikingly high survival rates of these molecules upon the harsh irradiation conditions to which they are submitted. We also evidence the interplay between the photochemical reactions of CO and CH(3)OH and those of the matrix. The OH and O radicals released by the photolysis of H(2)O and HNO(3) react with the CO and CH(3)OH and their fragments, considerably reducing the survival rates compared to pure CO and pure CH(3)OH ices, especially in presence of nitric acid, and dramatically enhancing the formation of CO(2) at the expense of CO. Because NEXAFS spectroscopy allows identifying which reactions are important among those possible, it emerges a simple picture of the photochemical routes of CO and CH(3)OH in the H(2)O and HNO(3)/H(2)O environments.

Synthesis and structures of copper(I) and cobalt(III) dimers with the dicyano-acetic acid methyl ester anion derived from TCNE

In the presence of CoCl2 · 6H2O or CuCl, the reaction of tetracyanoethylene and CH3OH provides a dicyano-acetic acid methyl ester anion (L1), which has been obtained as a bridged ligand in two compounds [(PPh3)2(NC)2CoIII(μ2-L12)CoIII(CN)2(PPh3)2] · (PPh3)(CH3OH) 1 and [(PPh3)2CuI(μ2-L12)CuI(PPh3)2] 2. The coordination geometry of the Co atom in 1 is distorted octahedral, and the Co atoms are μ2-bridged by two pairs of L. For compound 2, Cu is coordinated with two P atoms from PPh3 and two N atoms of L1, and two Cu atoms are linked by μ2-bridged L1.

Kinetics of the reaction of OH radicals with CH3OH and CD3OD studied by laser photolysis coupled to high repetition rate laser induced fluorescence

A new experimental set-up coupling laser photolysis to a 10 kHz dye laser as the excitation source for OH fluorescence has been validated by measuring the rate constant of the reaction CH3OH + OH. The rate constant of the deuterated homologue CD3OD + OH has been measured under the same conditions.

Mechanism of interaction of molecular hydrogen with adsorbed oxygen on platinum electrodes under open circuit conditions

Transients of open-circuit potential observed at the reaction of hydrogen molecules with oxygen preliminarily adsorbed (Oads) on the smooth polycrystalline (pc Pt) and platinized platinum (Pt/Pt) electrodes are measured under conditions of controlled stirring of solution (0.5 M H2 SO4). The dependence of the surface coverage with Oads(θO) on the potential in the cause of the potential decay on pc Pt are determined. It is found that for Pt/Pt, the reaction kinetics is largely determined by diffusion of H2. For pc Pt in the range of high θO, the Eley-Ridiel mechanism is realized. For medium θO, the regions where the reaction obeys the mechanisms of Eley-Ridiel, “conjugated reactions”, and diffusion control are observed to overlap (even at the most intense stirring possible). The rate of H2 reaction with Oads is substantially higher compared with analogous reactions of CO, HCOOH, and CH3OH.

Theoretical calculations of energetics, structures, and rate constants for the H+CH3OH hydrogen abstraction reactions

Barrier heights, structures, reaction energies, and rate constants are calculated with the DFT, MP2, and CCSD(T) methods for the first two channels of the H + CH3OH reactions. The best estimate results based on CCSD(T) calculations give reaction enthalpies (ΔH00) for the first (−8.4 kcal/mol) and second (0.8 kcal/mol) reactive channels, which are comparable to the experimental values, −8.8 ± 0.9 and −0.3 ± 0.9 kcal/mol, respectively. Rate constants and activation energies calculated with the IVTST-0 method using CCSD(T)/cc-pVTZ geometries and frequencies are also in excellent agreement with experiment data.

Ab initio quantum-chemical study of the mechanism of methoxide ion formation in MOH/DMSO/CH3OH systems (M = Li, Na, K)

The profile of the reaction CH3OH + MOH → CH3OM + H2O in the presence of an alkali (MOH, M = Li, Na, K) was investigated by the ab initio quantum-chemical method for the gas phase (with allowance for the solvent) within the continuum model. The proton transfer and the formation of the alkaline methoxide molecule in MOH/DMSO/CH3OH systems (M = Li, Na, K) in the alkali-methanol pre-reaction complexes can take place without their preliminary dissociation and are barrier-free reactions.

Imaging the Dynamics of Reactions between Cl Atoms and the Cyclic Ethers Oxirane and Oxetane

Direct current slice velocity map ion images of the HCl(nu' = 0, J') products from the photoinitiated reactions of ground state Cl atoms with ethane, oxirane (c-C2H4O), and oxetane (c-C3H6O), at respective mean collision energies of 5.5, 6.5, and 7.3 kcal mol-1(-1), were analyzed using a Legendre moment fitting procedure. The experimental method and the fitting technique were tested by comparing the derived center-of-mass (CM) frame angular scattering distribution for the HCl(v' = 0, J' = 1) products from the reaction of Cl + C2H6 with those determined by Suits and co-workers from a crossed molecular beam experiment. For the Cl + c-C2H4O reaction, a broad, forward, and backward peaking CM frame angular distribution of HCl(nu' = 0, J' = 2) products was determined, with an average fraction of the available energy released as product translational energy of f t, equal to 0.52 +/- 0.18. The HCl consumes only 1% of the available energy, and conservation arguments dictate that the radical coproduct is significantly internally excited, corresponding to an average fraction of the available energy of f int(c-C2H3O), equal to 0.47 +/- 0.18. For the reaction of oxetane with Cl atoms, abstraction of H atoms is possible from carbon atoms from positions either alpha or beta to the O atom. The contributions to the reaction from these two H-atom abstraction channels were estimated to be 63 and 37%, consistent with an unbiased propensity for removal of alpha- and beta-H atoms that are present in 2:1 abundance. The angular scatter of products in the CM frame is also broad and forward-backward peaking and is reminiscent of the products of the Cl + CH3OH and CH3OCH3 reactions. The derived mean fraction of the available energy channelled into product translation is f t = 0.54 +/- 0.12 for each of the two abstraction pathways. With only a small amount of energy in the rotation of the HCl(nu' = 0), the remainder is accounted for by excitation of the radical coproduct internal modes, with f int(c-C3H5O) = 0.42 +/- 0.12 for both alpha- and beta-H abstraction. The broad product scattering in the CM frame observed for both reactions of Cl atoms with the cyclic ethers is consistent with reactive collisions over a wide range of impact parameters, as might be expected for barrierless reactions with loose transition states.

Theoretical study of the hydrogen abstraction reaction of CH3OH with NCO

A direct dynamics method is employed to study the mechanism and kinetics of the hydrogen abstraction reaction of CH3OH with NCO. The optimized geometries and frequencies of the stationary points and the minimum-energy paths (MEPs) are obtained at the MP2/6-311G(d,p) level. In order to obtain more accurate potential energy surface (PES) information and provide more credible energy data for kinetic calculation, the single-point energies along the MEPs are further computed at QCISD(T)/6-311+G(d,p) and G3MP2 levels. The rate constants for two channels, the methyl-H abstraction channel and hydroxyl-H abstraction channel, are calculated by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) contributions over the wide temperature region 220–1500 K. The theoretical overall rate constants are in good agreement with the available experimental data. For the title reaction, the methyl-H abstraction channel is dominant, while the hydroxyl-H abstraction channel is negligible over the whole temperature region.

Effective Rate Constants for the Surface Reaction between Solid Methanol and Deuterium Atoms at 10 K

The surface reactions of CH3OH, CH2DOH, and CHD2OH with cold D atoms at 10 K were investigated using an atomic beam source and FTIR. Methyl-deuterated isotopologues CH2DOH, CHD2OH, and CD3OH were produced by exposure of amorphous solid CH3OH to D atoms at 10 K, and the pseudo-first-order rates for the reactions CH3OH + D --> CH2OH + HD, CH2DOH + D --> CHDOH + HD, and CHD2OH + D --> CD2OH + HD were estimated. The ratios of the reaction rates of the second and third reactions to the first reaction were 0.69 +/- 0.11 and 0.52 +/- 0.14, respectively. The difference in reaction rates is thought to be due to a secondary kinetic isotope effect on the H-abstraction reaction from the methyl side by D atoms.

Catalytic Conversion of Methanol by Oxidative Dehydrogenation

This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd 2+-TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH 3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH 3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH 3OH was converted to H 2O by oxidation. It has been shown that the H 2O was not produced from oxidative dehydrogenation by the direct reaction of CH 3OH and O 2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH 3OH was converted to CO 2 and dehydrogenated to HCOOCH 3, the C-O bonds were not dissociated.

Reaction of Methyl Alcohol with Thionyl Chloride in Solution

Reaction of CH3OH with SOCl2 producing CH3Cl and SO2 in two nonpolar(e15)and two polar(e15)solvents was studied using the B3LYP method and the SCIPCM model of the SCRF theory for simulating solution effects.The reaction process consists of reaction(1)and reaction(2)with CH3OS(O)Cl being a product of reaction(1)and the reactant of reaction(2).Reaction(2)has front-side substitution(via transition state TS3f)and back-side substitution(ionization of CH3OS(O)Cl followed by substitution via transition state TS3b)mechanisms.The calculations predicted that in gas phase and in the four solvents reactions(1)and(2)were exothermic and reaction(1)had the same reaction path(TS1→IM1→TS2).The calculations indicated that reaction(2)experienced very strong effects of solvent.In gas phase and in nonpolar solvents the front-side substitution was favored over the back-side substitution since TS3f is lower in energy than the(CH3OSO++Cl-)ion pair(IM2);and in polar solvents the back-side substitution was favored over the front-side substitution since IM2 and TS3b are lower in energy than TS3f.

Insight into the chemical reaction of CH 2OH with NO: Formation of N-hydroxy formamide as an isocyanic acid precursor

This study has explored the potential energy surface on the chemical reaction of CH 2OH with NO by using ab initio calculation. We have found the new reaction pathway producing N-hydroxy formamide, which can further decompose to generate isocyanic acid as a reducing agent of hydrocarbons selective catalytic reduction.

Influence of summertime deep convection on formaldehyde in the middle and upper troposphere over Europe

We present HCHO measurements performed during the Upper Tropospheric Ozone: Processes Involving HOx and NOx (UTOPIHAN) II aircraft campaign over central‐western Europe and the northwestern Mediterranean region in 2003 and 2004. We compare these with box model and three‐dimensional (3‐D) chemistry‐transport model results for “background” and “convective” conditions. Generally, we obtain good agreement between the model and measurement data, although the 3‐D model tends to underestimate HCHO near the tropopause, whereas the box model tends to slightly overestimate HCHO for the background case. Sensitivity simulations indicate that the most important factors determining HCHO concentrations are the abundances of NO, reactive hydrocarbons (e.g., isoprene), CH3OOH, CH3OH, and acetone and also the level of irradiance. In the middle and upper troposphere the most important HCHO production term is the reaction of CH3O2 with NO (68 ± 10%, including a contribution of 38 ± 7% from CH4 oxidation), followed by the destruction of CH3OOH by OH and photolysis (14 ± 2%), and the reaction of CH3OH with OH (14 ± 8%). HCHO loss is dominated by photolysis rather than by the reaction with OH, except in the upper tropospheric convective case, where the loss by OH contributes about 50%. Our measurements furthermore indicate that convective transport of H2O2 can be very efficient.

Theoretical Mechanistic Study on the Radical−Molecule Reaction of CH2OH with NO2

The complex singlet potential energy surface for the reaction of CH2OH with NO2, including 14 minimum isomers and 28 transition states, is explored theoretically at the B3LYP/6-311G(d,p) and Gaussian-3 (single-point) levels. The initial association between CH2OH and NO2 is found to be the carbon-to-nitrogen approach forming an adduct HOCH2NO2 (1) with no barrier, followed by C-N bond rupture along with a concerted H-shift leading to product P1 (CH2O + trans-HONO), which is the most abundant. Much less competitively, 1 can undergo the C-O bond formation along with C-N bond rupture to isomer HOCH2ONO (2), which will take subsequent cis-trans conversion and dissociation to P2 (HOCHO + HNO), P3 (CH2O + HNO2), and P4 (CH2O + cis-HONO) with comparable yields. The obtained species CH2O in primary product P1 is in good agreement with kinetic detection in experiment. Because the intermediate and transition state involved in the most favorable pathway all lie blow the reactants, the CH2OH + NO2 reaction is expected to be rapid, as is confirmed by experiment. These calculations indicate that the title reaction proceeds mostly through singlet pathways; less go through triplet pathways. In addition, a mechanistic comparison is made with the reactions CH3 + NO2 and CH3O + NO2. The present results can lead us to deeply understand the mechanism of the title reaction and may be helpful for understanding NO2-combustion chemistry.

C122 DFTによるDMFCアノード触媒反応の解析(OS-11 ナノスケール伝熱II)

Elucidation of mechanism on the anode of DMFC, that is catalytic reaction of CH3OH, is important for realization of the high efficiency and searching for an alternative catalyst to Pt and the alloy catalyst. In this study, adsorption energy of CH3OH with respect to each adsorption atom and each site investigated by using Density Functional Theory(DFT). Adsorption including OH band tends to stable and it is guessed the reaction on the catalyst takes place via that. Moreover, because of chasing the path after the adsorption, we think about the change in energy by comparing it with the state taking one H and by using a dynamic calculation.

Chemical and catalytic activity of copper nanoparticles prepared via metal vapor synthesis

Nanocrystalline particles of copper have been prepared using the solvated metal atom dispersion (SMAD) technique. Their chemical and catalytic reactivity have been tested in the Ullman reaction (aryl homocoupling) and the hydrogenation of CO2 to form CH3OH. The powders obtained from different solvents have surface areas of 24–30 m2/g, particle sizes of 20–45 nm, and crystallite sizes of 8–12 nm. The order of activity found toward the aryl homocoupling reaction is Cu*/toluene > Cu*/THF > Cu*/pentane > Cu*/diglyme, with a maximum biphenyl yield of 90% at 150 °C after 6 h for the Cu*/toluene sample. For the CO2 to CH3OH reaction, a maximum conversion of 80% was obtained for the Cu*/pentane/NC-ZnO sample. In general, the Cu*/nanocrystalline (NC)-ZnO samples show a larger conversion of CO2 to methanol at 450 °C compared with NC-ZnO and NC-ZnO/CuO.

Dissociative adsorption of HCOOH, CH 3OH, and CH 2O on MCM-41

Adsorption and surface reactions of HCOOH, CH 3OH, and CH 2O on siliceous mesoporous MCM-41 have been investigated by Fourier-transform infrared spectroscopy. CH 2O decomposes on the surface to form adsorbed CH 3O and HCOO (an analog of Cannizzaro disproportionation) which are identified by dissociative adsorption of CH 3OH and HCOOH. In addition, CH 3OH is sequentially oxidized to CH 2O and HCOO on MCM-41. These types of reactions for CH 2O and CH 3OH on MCM-41 have not been observed on amorphous SiO 2 without a mesoporous structure.