FORMATION AND CHARACTERISTIC PROPERTIES OF CARBONACEOUS SPECIES ON NICKEL-MAGNESIA SOLID-SOLUTION CATALYSTS DURING CH4-CO2 REFORMING REACTION

Carbonaceous species formed during the reforming of CH4 with CO2 over a series of NixMg1-xO solid solution catalysts and MgO-supported Ni ca talysts were characterized by temperature-programmed hydrogenation (TP H) method. Tao peaks appeared in the TPH spectra: one between 550 and 700 K (alpha-carbon) and another above 873 K (beta-carbon). It was fou nd that a good relationship exists between the quantity of alpha-carbo n species and the catalytic activity, indicating that alpha-carbon sho uld be the reaction intermediate. In addition, the amount of beta-carb on increased with increasing reaction time, especially on the supporte d Ni/MgO catalysts which make inactive carbon during the CH4-CO2 refor ming reaction. (C) 1997 Elsevier Science B.V.