SUPPRESSION OF CARBON DEPOSITION IN THE CO2-REFORMING OF CH4 BY ADDING BASIC METAL-OXIDES TO A NI AL2O3 CATALYST/

The effect of the oxides of Na, K, Mg, and Ca on CO2-reforming of CH4 over Ni/Al2O3 catalysts was studied from the viewpoint of carbon depos ition. These added oxides markedly suppressed the carbon deposition du ring CO2-reforming, also in the absence of CO2. It was concluded that the suppression of carbon deposition resulted from the decrease in the ability of Ni catalyst for CH4 decomposition. It was also observed th at the added basic metal oxides changed the reaction order from negati ve to positive with respect to the partial pressure of CH4 and from po sitive to negative with respect to the partial pressure of CO2. The ob served reaction kinetics suggested that the surface of the Ni catalyst with basic metal oxides was abundant in adsorbed CO2, while the surfa ce without them was abundant in adsorbed CH4. The abundance in adsorbe d CO2 on the Ni metal surface was considered an unfavorable condition for CH4 decomposition and as a result, carbon deposition was further s uppressed during CO2-reforming on Ni/Al2O3 catalysts with basic metal oxides.