Deactivation behavior of Pd-based SBA-15 mesoporous silica catalysts for the catalytic combustion of methane

A series of Pd/SBA-15 and Pd/5% Ce1−xZrxO2/SBA-15 (x=0–1)(x=0–1) catalysts with Pd content ranging from 0.05% to 1% were prepared. The activity and stability of the catalysts for the combustion of methane were evaluated. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, CO chemisorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR). Deactivation behavior of the catalysts for the catalytic combustion of methane was investigated. The results show that all of the catalysts retained the SBA-15 mesoporous structure, with PdO and Ce1−xZrxO2 being confined in the channels. It is proposed that deactivation of the catalysts is associated with accumulation of Pd0, which cannot be efficiently reoxidized to PdO or PdO2, due to the limited oxygen-transfer ability of the catalysts. The incorporation of the ZrO2 as a promoter leads to an increase in the oxygen storage capacity and oxygen mobility of the catalysts, which in turn increases the rate of oxidation of Pd0 and mitigates deactivation of the catalyst.