Catalytic hydrogenation of carbon dioxide over LaNi 5 activated during the reaction

Abstract

The hydrogenation of carbon dioxide to methane can be catalyzed over an intermetallic compound of LaNi 5 at 250–350°C. The catalytic activity at 250°C increases during the reaction while X-ray diffraction (XRD) analyses show that the structure of the compound decomposes to La(OH) 3, LaCO 3OH, and metallic nickel. Formation of metallic nickel species during the reaction also takes place in a nickel–lanthanum oxides catalyst prepared by a coprecipitation method, however, the activity is not so high as the former catalyst. Surface analyses by X-ray photoelectron spectroscopy (XPS) suggest that new nickel species interacting with lanthanum cation, possibly Ni–O–La, are formed in LaNi 5 during the reaction, and the species are supposed to be rather active than metallic nickel.