EFFECT OF THE METHOD OF PREPARING RU-MO/SIO2 CATALYSTS IN THEIR BEHAVIOR IN CO HYDROGENATION

Sequential impregnation of SiO2 by RuCl3 and then by (NH4)6Mo7O24, followed by drying and reduction in H2 at 623 K, afforded catalysts in which, according to their benzene hydrogenation activity, the Ru particles were progressively covered by Mo-containing species, the effect being greatest when RuCl3 was introduced first. With catalysts of this type, in CO hydrogenation, oxygenate formation occurred at low Mo content but was eliminated as the Mo concentration was increased. When the Mo salt was applied first to the support, oxygenate formation was greater and did not diminish significantly on raising the Mo content. A semi-quantitative model is developed in which oxygenates are formed at Ru-Mo sites; the hydrocarbon-forming process is not however much inhibited by the presence of Mo, and may take place on Mo species covering the Ru particles.