A bimetallic PdPt catalyst on CeZrO₂/H-ZSM-5 dual support with exceptional activity in low temperature methane oxidation

Various techniques were employed to prepare a dual support system of CeZrO2 and H-ZSM-5 (80) including physically mixing, co-precipitation and sonochemical methods, which were followed by the deposition of bimetallic Pd and Pt via wet impregnation to obtain the final catalysts. The catalysts were tested in the total methane oxidation between 200 and 500 & DEG;C and the most active is the material derived from sonochemical synthesis. This catalyst achieved a remarkable methane conversion of 84% at a low temperature of 300 & DEG;C and high Gas Hourly Space Velocity (GHSV) of 100000 ml g(-1) h(-1). Characterisation using x-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), scanning transmission electron microscope (STEM), Energy-dispersive x-ray spectroscopy (EDS), temperature-programmed reduction (TPR) and x-ray absorption fine structure (XAFS) techniques revealed the intimate distribution of catalyst components and facile redox behaviour of both Pd and CeZrO2 components. The catalysts based on sonochemical CeZrO2 was proven to be relatively stable with only 7% methane conversion loss after 50 h continuously on stream at 300 & DEG;C compared to the corresponding 14% witnessed with the commercial TiO2-based material.