Comparative Study on Steam and Oxidative Steam Reforming of Methane with Noble Metal Catalysts

Methane steam reforming (SR) and oxidative steam reforming (OSR) are two catalytic processes for generating syngas. Catalysts based on Ru, Rh, and Pt noble metals deposited over CeO2 and Al2O3 carriers were prepared by solution combustion synthesis and tested toward the methane SR reaction. The best catalysts were further tested toward the methane OSR reaction, to see any benefit coming from the presence of a slight amount of oxygen. These catalysts were then characterized using Brunauer-Emmet-Teller (BET), CO chemisorption, transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The highest conversion of methane was reached by the 1.5% Rh/CeO2 catalyst for the methane SR reaction and by the 1.5% Ru/Al2O3 for the methane OSR reaction. These two best catalysts were then further compared in terms of hydrogen concentration, yield, H-2-to-CO molar ratio, and CO2-to-CO selectivity ratio. The 1.5% Rh/CeO2 catalyst for SR performed better than the 1.5% Ru/Al2O3 catalyst for OSR reaction, as it gave complete methane conversion at lower temperature (635 degrees C), higher CO2 selectivity (87.5%), and higher hydrogen concentration (74.4% dry volume). Its good catalytic activity could be ascribed to the high Rh dispersion over the CeO2 carrier.