CO Hydrogenation on Supported Metal Catalysts under Periodic Operation

The performance of catalysts for CO hydrogenation under periodic operations are studied. The noble metal (Ru, Rh, Pt, Ir, and Pd) and base metal (Fe and Co) catalysts were prepared by a conventional impregnation method. In the periodic operation, pure H2 and 33.3 vol% CO (N2 balance) were alternately and symmetrically injected as a rectangular wave just before a catalyst bed. A concentration of hydrocarbon -mainly methane- formed on catalysts was measured as a function of the reaction temperatures and injection periods. Except Pt catalyst, all catalysts showed a favorable cycling period dependency, that is, catalytic activity was always improved under periodic operations. The particular period for the maximum concentration of hydrocarbons decreased with rise in reaction temperature. There are some correlations between the activities of catalysts examined and the peak temperatures of CO2 desorption profiles in TPD. The favorable effect on the hydrocarbon formation may be explained by reduced poisoning of CO on catalyst surface.