Yttrium stabilization and Pt addition to Pd/ZrO2 catalyst for the oxidation of methane in the presence of ethylene and water

Abstract

Catalytic oxidation is the most efficient method of minimizing the emissions of harmful pollutants and greenhouse gases. In this study, ZrO₂-supported Pd catalysts are investigated for the catalytic oxidation of methane and ethylene. Pd/Y₂O₃-stabilized ZrO₂ (Pd/YSZ) catalysts show attractive catalytic activity for methane and ethylene oxidation. The ZrO₂ support containing up to 8 mol% Y₂O₃ improves the water resistance and hydrothermal stability of the catalyst. All catalysts are characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), O₂-temperature-programmed desorption (O₂-TPD), and CO-chemisorption techniques. It shows that high Pd dispersion and Pd–PdO reciprocation on the Pd/YSZ catalyst results in relatively high stability. In situ diffuse reflectance infrared Fourier-transform (DRIFT) experiments are performed to study the reaction over the surface of the catalyst. Compared with bimetallic catalysts (Pd : Pt), the same amounts of Pd and Pt supported on ZrO₂ and Y₂O₃-stabilized ZrO₂ catalysts show enhanced activity for methane and ethylene oxidation, respectively. A mixed hydrocarbon feed, containing methane and ethylene, lowers the CH₄ light-off temperature by approximately 80 °C. This shows that ethylene addition has a promotional effect on the light-off temperature of methane.