Low-energy paths for the unimolecular decomposition of CH3OH: A G2M/statistical theory study

Xia, W. S.; Zhu, R. S.; Lin, Ming‐Chang; Mebel, Alexander M.

doi:10.1039/b102057i

Cited by 42 publications

(135 citation statements)

References 29 publications

(1 reference statement)

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“…The thermal decomposition of methanol has been studied previously [9,10]. Seven decomposition pathways have been identified using theory [3,4], but at combustionrelevant conditions the dominant channels are…”

Section: Introductionmentioning

confidence: 99%

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

Vasudevan

Cook

Hanson

et al. 2008

Int J of Chemical Kinetics

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The reaction between methyl and hydroxyl radicals has been studied in reflected shock wave experiments using narrow-linewidth OH laser absorption. OH radicals were generated by the rapid thermal decomposition of tert-butyl hydroperoxide. Two different species were used as CH 3 radical precursors, azomethane and methyl iodide. The overall rate coefficient of the CH 3 + OH reaction was determined in the temperature range 1081-1426 K under conditions of chemical isolation. The experimental data are in good agreement with a recent theoretical study of the reaction. The decomposition of methanol to methyl and OH radicals was also investigated behind reflected shock waves. The current measurements are in good agreement with a recent experimental study and a master equation simulation. C 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 488-495, 2008

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Section: Introductionmentioning

confidence: 99%

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

Vasudevan

Cook

Hanson

et al. 2008

Int J of Chemical Kinetics

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“…A linear least-square analysis of the computed data gives the Arrhenius expression k CH 3 OH = 1.96 × 10 −11 exp(−355/T ), showing a low activation barrier of E a = 705 cal/ mol −1 . For those channels studied in the past [5][6][7][8], the highest channel energy state is for the reaction CH 3 + OH → CH 3 O + H. The interaction energy U depends strongly on the reactant orientations θ and φ. The orientations at the instant of intermediate formation determine the pathway that reaction follows.…”

Section: Resultsmentioning

confidence: 98%

“…Sandia [51] and NIST [52] values are 93.1 and 92.14 kcal mol −1 , respectively. Ab initio calculations give the dissociation energy of CH 3 OH → CH 3 + OH ranging from 84.1 to 97.8 kcal mol −1 depending on the numerical methods used [6]. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of the CH₃ + OH reaction

Ree

Kim

Shin

2011

Int J of Chemical Kinetics

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We study dynamics of the CH 3 + OH reaction over the temperature range of 300-2500 K using a quasiclassical method for the potential energy composed of explicit forms of short-range and long-range interactions. The explicit potential energy used in the study gives minimum energy paths on potential energy surfaces showing barrier heights, channel energies, and van der Waals well, which are consistent with ab initio calculations. Approximately, 20% of CH 3 + OH collisions undergo OH dissociation in a direct-mode mechanism on a subpicosecond scale (<50 fs) with the rate coefficient as high as ∼10 −10 cm 3 molecule −1 s −1 . Less than 10% leads to the formation of excited intermediates CH 3 OH † with excess vibrational energies in CO and OH bonds. CH 3 OH † stabilizes to CH 3 OH, redissociates back to reactants, or forms one of various products after intramolecular energy redistribution via bond dissociation and formation on the time scale of 50-200 fs. The principal product is 1 CH 2 (k CH 2 being ∼10 −11 ), whereas ks for CH 2 OH, CH 2 O, and CH 3 O are ∼10 −12 . The minor products are HCOH and CH 4 (k ∼10 −13 ). The total rate coefficient for CH 3 + OH → CH 3 OH † → products is ∼10 −11 and is weakly dependent on temperature. C

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“…The dissociation energy of 87.6 kcal/mol was found at MRCIþQ/CBS//CAS(10,10)/cc-pVDZ level (were CBS refers to an extrapolation from the aug-cc-pVDZ and aug-cc-VTZ basis sets), [52] which is close to our MRPT(6,4)/ CCD//CAS(6,4)/CCD value. Xia et al [22] report dissociation limits for CH 3 OH ! CH 3 þ OH calculated at different levels: B3LYP/6-311G(d,p) (85.4 kcal/mol), MP2/6-311G(d,p) (97.8 kcal/mol), MP2/6-311þG(3df,2p) (95.2 kcal/mol), CCSD(T)/6-311G(d,p) (84.1 kcal/mol), and G2M(cc2) (91.9 kcal/mol).…”

Section: Ohmentioning

confidence: 99%

“…The use of alcohols as fuels for internal combustion engines has been considered a promising renewable energy resource and considerable attention has been given to methanol reactions as it is an important alternative fuel. Theoretical calculations and experimental works aiming for the thermal decomposition of CH 3 OH are available in the literature [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] although new investigations of the elementary reactions have been encouraged, specially the unimolecular dissociation (Reaction I), which appears as the main important step in the thermal decomposition kinetic model. [26] The main goal of this article is to evaluate the implementation of the canonical variational TST in the kcvt program, as well as to investigate the calculation of rate constants within different models for treating low vibrational frequencies and their contribution for the reaction dynamics.…”

Section: Introductionmentioning

confidence: 99%

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

Oliveira¹,

Bauerfeldt²

2012

Int J of Quantum Chemistry

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Here, a new implementation for calculating canonical variational rate constants is introduced and tested against methanol dissociation rate constants and the (high pressure) radical recombination reaction, CH 3 þ OH ! CH 3 OH. Reaction paths are described at the CASSCF level, with energy corrections at MRMP2. Molecular properties for both stationary and non-stationary points along the reaction path are used for the calculation of rate constants. Different models for the low vibrational frequencies are discussed: harmonic oscillator and free rotor models. The CH 3 þ OH ! CH 3 OH recombination rate constants are determined from dissociation rate constants and equilibrium constants. Our calculated rate constants agree with previously reported data for these reactions, suggesting the good performance of our implemented code in calculating canonical variational rate constants. The rate expressions are suggested: as: k dis (T) ¼ 8.42 Â 10 þ16 Â e À96.18/RT and k rec (T) ¼ 2.05 Â 10 À10 Â (T/298) À0.24 Â e À0.30/RT , in units s À1 and cm 3 molecule À1 s À1 , respectively, and over the temperature range 300-2000 K, with activation energies in kcal/mol.

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Low-energy paths for the unimolecular decomposition of CH3OH: A G2M/statistical theory study

Cited by 42 publications

References 29 publications

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

Dynamics of the CH₃ + OH reaction

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH

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Low-energy paths for the unimolecular decomposition of CH3OH: A G2M/statistical theory study

Cited by 42 publications

References 29 publications

High‐temperature shock tube study of the reactions CH3 + OH → products and CH3OH + Ar → products

High‐temperature shock tube study of the reactions CH3 + OH → products and CH3OH + Ar → products

Dynamics of the CH3 + OH reaction

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH3OH = CH3 + OH

Contact Info

Product

Resources

About

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

High‐temperature shock tube study of the reactions CH₃ + OH → products and CH₃OH + Ar → products

Dynamics of the CH₃ + OH reaction

Implementation of a variational code for the calculation of rate constants and application to barrierless dissociation and radical recombination reactions: CH₃OH = CH₃ + OH