Chain propagation reaction OH+CH4->H2O+CH3
The reaction OH+CH4->H2O+CH3 is one of the chain-propagation reactions in the practically important process of methane combustion. The rate constant of this reaction was evaluated using the transition state theory. This theory is applicable if only one potential barrier occurs in the reaction path from the reagents to the products and there are no deep potential wells (see left figure). The height of the potential barrier between the reagents and products and the parameters characterizing the structure of the transition complex (rotational constants, vibrational frequencies) were calculated by Kintech Lab team using quantum-chemical program package GAUSSIAN-03. The parameters of potential energy surfaces needed for implementing model calculations of bimolecular chemical reactions can also be evaluated using commercially available quantum chemical program packages (GAUSSIAN, GAMESS) and read directly from the output files of these programs.
The results of calculations are presented in the right figure along with the available experimental data. It can be seen that the transition state theory with the parameters obtained from quantum-chemical calculations provides the quantitative description of the direct bimolecular reaction.
- Reaction energy path profile of the direct bimolecular reaction X+Y->Z+W.
- Rate constant k of the reaction OH+CH4-> H2O+CH3. Experimental data was taken from Baulch, D.L., Bowman, C.T., Cobos, C.J., et al Journ. Phys. Chem. Ref. Data 2005, 34, 757.
