Three-dimensionally ordered macroporous CeO2-supported Pd@Co nanoparticles: Highly active catalysts for methane oxidation

Abstract Three-dimensionally ordered macroporous CeO 2 (3DOM CeO 2 ) and its supported Pd@Co (Co x Pd/3DOM CeO 2 , x (Co/Pd molar ratio) = 2.4–13.6) nanocatalysts were prepared using the polymethyl methacrylate-templating and modified polyvinyl alcohol-protected reduction methods, respectively. The Pd@Co particles displayed a core-shell (core: Pd; shell: Co) structure with an average size of 3.5–4.5 nm and were well dispersed on the surface of 3DOM CeO 2 . The Co x Pd/3DOM CeO 2 samples exhibited high catalytic performance and super stability for methane oxidation, with the Co 3.5 Pd/3DOM CeO 2 sample showing the highest activity ( T 90%  = 480 °C at space velocity of 40,000 mL/(g h) and excellent stability in the temperature range 400–800 °C. The apparent activation energies (58–73 kJ/mol) obtained over Co x Pd/3DOM CeO 2 were much lower than those (104–112 kJ/mol) over Co/3DOM CeO 2 and 3DOM CeO 2 for methane oxidation, with the Co 3.5 Pd/3DOM CeO 2 sample possessing the lowest apparent activation energy (58 kJ/mol). It is concluded that the excellent catalytic performance of Co 3.5 Pd/3DOM CeO 2 was associated with its good abilities to adsorb oxygen and methane as well as the unique core-shell structure of CoPd nanoparticles.