Microkinetic Mechanisms for Partial Oxidation of Methane over Platinum and Rhodium

Abstract

A systematic approach for the development of heterogeneous mechanisms is applied and evaluated for the catalytic partial oxidation of methane over platinum (Pt) and rhodium (Rh). The derived mechanisms are self-consistent and based on a reaction class-based framework comprising variational transition state theory (VTST) and two-dimensional collision theory for the calculation of pre-exponential factors with barrier heights obtained using the unity bond index–quadratic exponential potential (UBI–QEP) method. The surface chemistry is combined with a detailed chemistry for the gas phase, and the accuracy of the approach is evaluated over Pt for a wide range of stoichiometries (0.3 ≤ ϕ ≤ 4.0), pressures (2 ≤ P (bar) ≤ 16), and residence times. It is shown that the derived mechanism can reproduce experimental data with an accuracy comparable to that of the prevalent collision theory approach and without the reliance on experimental data for sticking coefficients. The derived mechanism for Rh shows encouraging ...