CARBON-MONOXIDE HYDROGENATION ON SUPPORTED RH-MN CATALYSTS

Silica-supported manganese-promoted rhodium catalysts previously observed to contain a form of adsorbed CO assigned to a tilted Rh-C-O-Mn species show a higher specific activity for the hydrogenation of carbon monoxide than do unpromoted samples. This enhanced activity manifests itself primarily through increased formation of C2+ products. The activation energy for chain growth was significantly higher on the promoted sample. These observations suggest that the promoted catalyst presumably provides a greater number of active sites, and that the insertion mechanism may be altered as compared to the unpromoted material. No direct evidence exists for the participation of the tilted species in the CO/hydrogen reaction, although its participation in chain growth is considered possible.