THEORETICAL-ANALYSIS OF METHANE DECOMPOSITION AT THE NI(100) SURFACE

The potential energy profile for methane dissociative adsorption at th e Ni(100) surface is calculated using the ab initio Hartree-Fock metho d. The stationary points are determined, which correspond to the metha ne molecular adsorption, transition state (activated complex), and rea ction products in the reaction path of the methane decomposition into CH3. and H.. From the analysis of calculated results, it follows that the adsorption state of molecular methane depends on the electron-acce ptor properties of the nickel surface, whereas the electron-donor prop erties of the surface are essential for the dissociative adsorption. T he gain in energy due to the dissociative adsorption from the gas phas e and the potential barrier for this channel of the reaction are estim ated at 88 and 54 kJ/mol, respectively. Modem concepts of the mechanis m of methane decomposition at metal surfaces are briefly discussed.