Kinetic investigation of the promoting effect of cobalt on Pd-Pt/SnO2 catalyzed wet methane combustion

Abstract

This study is focused on developing a stable and active catalyst for lean-burn methane combustion in the presence of water. By varying the cobalt loading, it was found that 10 wt% Co deposition enhanced the hydrothermal stability of the 1 wt% Pd-Pt (1:1 molar ratio)/SnO2 catalyst. Kinetic investigation of methane combustion on the hydrothermally aged Pd-Pt/10Co/SnO2 catalyst under 5 and 10 vol% water was performed. While SnO2 dictated the kinetics in terms of activation energy (89 ± 9 kJ mol−1), Co addition altered the reaction order to water (n = −0.37). In terms of turnover frequency, the Pd-Pt/10Co/SnO2 catalyst surpassed the Al2O3-supported catalyst formulations. Reaction rates normalized per total catalyst mass at 773 K and 10 vol% added water were found in the order of Pd/Al2O3(“x”) < Pd-Pt/Al2O3 (1.5x) < Pd-Pt/SnO2 (1.6x) < Pd-Pt/10Co/SnO2 (14x), consequently suggesting that the utilization of the Pd-Pt/10Co/SnO2 catalyst could result in small catalytic converter volumes.