Palladium-based catalysts for methane oxidation by co-flow diffusion flame synthesis

Pd supported on mixed ceria-titania oxide catalysts are synthesized with a co-flow diffusion flame, and the catalytic activities for CH4 oxidation are evaluated in a lab-scale fixed bed. The as-prepared catalysts exhibit high catalytic activities and good Pd cluster distribution. Among them, Pd supported on pure CeO2 is found to show the best performance. The results show that it has fairly low T10, and complete oxidation occurs as low as 400 °C. It is deduced that three factors facilitate the reaction between the adsorbed CH4 and O2, namely, solid-solution-like PdxCe1-xO2 structures, highly active sites provided by atomic-level assembly during the flame synthesis, and the presence of lattice oxygen. Additionally, the deactivation of the catalyst may be caused by the decreasing of lattice oxygen, the reduction of PdO and the instability of PdxCe1-xO2. These results may aid in the development of better catalytic nanomaterials for clean methane oxidation.