Oxidative coupling of methane over sodium zirconate catalyst

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.