The effect of lanthanum addition on the catalytic activity of gamma-alumina supported bimetallic Co-Mo carbides for dry methane reforming

The effect of lanthanum addition to c-alumina supported bimetallic carbides has been studied for the reaction of dry methane reforming using four different lanthanum loading levels of 1, 5, 10 and 15 wt% of lanthanum. It has been demonstrated that the addition of lanthanum to supported bimetallic carbides at low loading levels (1 wt%) results in smaller carbide crystallite sizes compared to catalysts containing either no lanthanum or higher lanthanum loading levels (5-15 wt%). Increased lanthanum loading results in increased carbon dioxide desorption at 500-700 degrees C. Reactions indicated that increased lanthanum loading resulted in significantly reduced product yields due to increased reverse water-gas shift activity. All materials exhibited degrees of sintering during the reaction. It was found that cobalt reacted with lanthanum species to form a LaCoO3 phase. The 1 wt% catalyst possessed superior catalytic properties for dry methane reforming and was tested for 100 h. After an initial loss of activity, the catalyst appeared to stabilise, however, a decrease of similar to 3 % in the H-2:CO ratio, evidence of carbide crystallite growth and carbon deposition, indicated that a shift in the side reactions had occurred during the reaction.