CONVERSION OF CARBON OXIDE (S) ON CARBON-SUPPORTED, NICKEL RARE-EARTH CATALYSTS

The catalytic properties of carbon-supported nickel catalysts depend heavily on the presence of lanthanum or cerium promoters. After addition of these elements, the activity and the hydrocarbon selectivity in (CO, H-2) or (CO2, H-2) reactions increase while the T.O.F. of benzene hydrogenation is much less modified. Adsorption measurements and analytical microscopy data indicate that: (i) the nickel dispersion is favoured, particularly with cerium addition; (ii) the rare-earth element is well distributed over the charcoal surface. The formation of specific active centers is therefore favoured at the metal-support interface, leading to important changes in carbon monoxide or carbon dioxide adsorption states and in hydrogenation.