REFORMING OF METHANE WITH CARBON-DIOXIDE TO SYNTHESIS GAS OVER SUPPORTED RH CATALYSTS

Reforming of methane with carbon dioxide to synthesis gas (CO/H-2) has been investigated over rhodium supported on SiO2, TiO2, gamma-Al2O3, MgO, CeO2, and YSZ (ZrO2 (8 mol% Y2O3)) catalysts in the temperature r ange of 650-750 degrees C at 1 bar total pressure. A strong carrier ef fect on the initial specific activity, deactivation rate, and carbon a ccumulation was found to exist. A strong dependence of the specific ac tivity of the methane reforming reaction on rhodium particle size was observed over certain catalysts. Tracing experiments (using (CH4)-C-13 ) coupled with temperature-programmed oxidation (TPO) revealed that th e carbon species accumulated on the surface of the Rh/Al2O3 catalyst d uring reforming reaction at 750 degrees C are primarily derived from t he CO2 molecular route. The amount of carbon present on the working ca talyst surface which is derived from the CH4 molecular route is found to be very small.