Methanol Oxidation Catalytic Performance Enhancement via Constructing Pd-MgAl2O4 Interface and its Reaction Mechanism Investigation.

The methanol oxidation reaction is a promising route to eliminating trace amount of methanol in exhaust gases which aroused serious environmental concern. In this work, a novel Pd/MgAl2O4 catalyst was prepared to construct the metal-support interface and employed in the methanol oxidation reaction. The reaction results show that the Pd/MgAl2O4 catalyst could achieve 100% methanol oxidation at 198 ℃ over the Pd/MgO and Pd/Al2O3 catalysts. The high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), CO-chemisorption, H2 temperature programmed reduction (H2-TPR), and CO diffuse reflectance infrared Fourier transformed spectroscopy (CO-DRIFTS) show that the Pd was uniformly distributed over the MgAl2O4 support due to strong interaction between Pd and MgAl2O4. The mechanism studies show that the abundant Pd-MgAl2O4 interfaces significantly contributed to the reaction enhancement. The Pd-MgAl2O4 interfaces could greatly enhance the oxidation reaction at a lower temperature with the assistance of oxygen vacancies compared with traditional oxide catalysts, which was confirmed by methanol temperature program surface reaction (MeOH-TPSR) experiments. In-situ DRIFTS is carried out to elucidate the reaction mechanism and establish the structure − activity relationship: the methanol could be effectively absorbed on the MgAl2O4 support with oxygen vacancies to form bidentate formate, then the Pd species assisted the intermediates converting to CO2 product. The Pd/MgAl2O4 catalyst and its enhancement mechanism investigation provided a potential strategy in the VOCs removal catalysis development. [ABSTRACT FROM AUTHOR]