In situ DRIFTS investigation of the promoting effect of Zr on Pd/Al ₂O₃ catalyst for the catalytic combustion of methane

Surface species formed during the catalytic combustion of methane over Al₂O₃ supported Pd and Pd-Zr catalysts have been investigated by in situ DRIFTS techniques. It is found that formate and carbonate ions are formed during the reaction as intermediates, and the further oxidation of formate ion to carbonate ion requires reactive oxygen species supplied by activating gaseous oxygen at oxygen vacancies on the catalyst surface. Modification of Pd/Al₂O₃ catalyst by Zr addition leads to the increase of oxygen vacancy, which promotes the activation of gaseous oxygen and contributes to the oxidation of formate ion, resulting in a higher catalytic performance for the catalytic combustion of methane.