A study of the promoting effect of noble metal addition on niobia and niobia alumina catalysts

The catalytic activity of Nb2O5 and Nb2O5/Al2O3-supported metal catalysts w as evaluated in the n-heptane conversion, CO hydrogenation and butadiene hy drogenation. After high temperature of reduction (HTR), the metal adsorptio n capacity decreases on all the samples, due to the reduction of Nb2O5 With subsequent blocking of metal atoms and bimetallic effect. It was also observed that the activity decay caused by metal-support intera ction was remarkably inhibited on the bimetallics with respect to the monom etallics by comparing reaction rates after HTR. Thus, the addition of Rh to Co, Cu to Pd and Sn to Pt on niobia catalysts significantly altered the pr oduct distribution in Fischer-Tropsch synthesis (FTS) and in the hydrogenat ion and dehydrogenation of hydrocarbons, respectively. In addition, an unus ual bifunctional effect was obtained in Pt/Nb2O5/Al2O3 catalyst. (C) 2000 E lsevier Science B.V. All rights reserved.