Oxidative coupling of methane over sodium zirconate catalyst

Abstract

We report the oxidative coupling of methane (OCM) performance over Na₂ZrO₃ under various temperatures, CH₄/O₂ ratios, and reaction pressures. Sensitivity of CH₄ conversion rate was investigated with respect to feed components CH₄ and O₂ pressures, as well as reaction products CO₂ and H₂O pressures. Kinetic data obtained under various conditions were fitted to establish an OCM reaction network to describe the product distribution based on the rate constants at each reaction step. Temperatures above 750 °C caused gradual decay in catalytic performance, likely due to Na loss associated with the transformation of Na₂ZrO₃ crystal phase to monoclinic ZrO₂. This catalyst exhibited competitive inhibition by reversible CO₂ adsorption and CO oxidation activity, both of which were necessary to include to construct an accurate kinetic model.