H-abstraction reaction from methane in straight channel of H-ZSM-5 zeolite containing O(3P) atom: a D-DFT study

Zeolites are crystalline microporous alumino-silicates characterized by internal cavities and channels of molecular dimensions which allow the use of these materials in different catalytic or separation processes. On the other hand, O(3P) species is well known for its excellent performance in oxidation processes. In this contribution, by first principle Density Functional Theory corrected by semi-empirical dispersion forces (D-DFT)[1,2] calculations, using plane waves expansions and ultrasoft pseudopotentials, we show that triplet oxygen atom, anchored by acidic site in H-ZSM-5 zeolite, plays a catalytic role in the H-abstraction reaction from CH4 to produce (OH)-and CH3 radical. Open shell systems were treated using unrestricted formalism and zeolite was modeled by its crystallographic structure subject to periodic boundary conditions [3]. The reaction is found to be strongly exothermic and a reaction mechanism, with a relatively small energy barrier, is proposed.