Catalytic behavior of lanthana promoted Rh/SiO2 catalysts: influence of the preparation procedure

Benzene hydrogenation and n-butane hydrogenolysis reactions have been tested on a series of Rh/La2O3/SiO2 catalysts, their catalytic properties bring compared with those of a Rh/SiO2 sample studied as reference. This investigation has revealed that both activity and selectivity can be controlled by the procedure followed to prepare the catalysts. In particular, the influence of preparative conditions such as the lanthana loading, method of introduction of the metal and promoter (either consecutive or by co-impregnation) and temperature of calcination (873 or 1173 K) of the intermediate La2O3/SiO2 phase onto which the noble metal is later deposited, have been analyzed. The differences in the catalytic behavior have been correlated with the La2O3/SiO2 interactions. leading to a different degree of surface hydroxylation and different Rh particle crystallinity. (C) 2001 Elsevier Science B.V. All rights reserved.