THE INFLUENCE OF TIO2 ON THE SPECIATION AND HYDROGENATION ACTIVITY OF CO/AL2O3 CATALYSTS

The influence of TiO2 on the distribution of supported species in 3 wt% Co/Al2O3 catalysts has been examined by X-ray diffraction, X-ray photoelectron spectroscopy (ESCA), Raman spectroscopy (LRS), and gravimetric analysis. The results show that for unmodified catalysts with low Ti loadings (<4 wt% Ti) the Co phase is present primarily as Co3O4 with lesser amounts of surface octahedral and tetrahedral cobalt [Co(o); Co(t)]. For catalysts having high Ti contents, Co3O4 formation is suppressed with increasing Ti loadings in favor of a CoTiO3-like surface phase. Benzene and CO hydrogenation activity measurements indicate that Ti addition decreases the catalytic activity for both reactions. This has been attributed primarily to site blocking which results from the migration of reduced Ti species. © 1990.