Preparation and properties of raney catalysts from rare earth intermetallic compounds

Abstract

Raney-type catalysts were prepared from various rare earth intermetallic compounds (LaNi 5, LaNi, LaCo 5, SmCo 5, Sm 2Co 7 and SmCo 2) and their catalytic properties were examined. In preparing the Raney catalysts, solutions of 1,2-diiodoethane (DIE) or 1,2-dibromoethane (DBE) in methanol or tetrahydrofuran were used for leaching out rare earths components from the rare earth-Ni (or Co) intermetallics. The rare earths were removed from the alloys by means of DIE or DBE solutions in the form of halide. In this system the effect of the solvent was also important in the catalyst preparation and was investigated. The morphology of the catalysts was characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and adsorption studies. Highly active Raney catalysts were prepared by leaching out the rare earth elements from LaNi and SmCo 2 in DIE or DBE solutions, leaving a spongy, high surface area skeleton of nickel and cobalt. The catalytic properties examined by the hydrogenation and dehydrogenation reactions were very dependent upon the rare earth leaching procedure, crystal structure of the precursor intermetallics, digestion conditions and thermal pretreatment of the catalysts.