Promotion effect of palladium on Co 3 O 4 incorporated within mesoporous MCM-41 silica for CO Oxidation

Co 3 O 4 incorporated within mesoporous MCM-41 silica have been successfully synthesized and promoted with Pd nanoparticles through a microwave irradiation (MWI) approach. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N 2 -physisorped, X-ray photoelectron spectroscopy (XPS), temperature program reduction of hydrogen (H 2 -TPR), temperature program desorption of oxygen (O 2 -TPD) and high resolution transmission electron microscopy (HRTEM) were adapted to characterize these prepared catalysts. Carbon monoxide oxidation as a model reaction was then used to assess the catalytic performance of these materials. In the light of H 2 -TPR and XPS results, revealed that the coexisting of Co 3+ and Co 2+ species as well as surface Co 3+ /Co 2+ ratio within the hexagonal mesoporous of MCM-41, could create an ideal environment to accomplish most extreme catalytic activity. On the other hand, the enhanced CO oxidation by Pd nanoparticles deposition has been explained in the light of the enhancement of the redox ability and tuning the electronic structure of Co 3 O 4 , which improved the O 2 activation and reduced the adsorption ability of CO simultaneously, which significantly boosted the catalytic performance of CO oxidation. This work provides insights into factors that could lead to improved low temperature CO oxidation performance in Pd-based catalysts.