The effect of rhodium precursor on Rh/Al2O3 catalysts

Abstract
The infrared spectra of the CO/Rh/Al2O3 system have been examined following several different means of preparing the supported rhodium catalyst. Rhodium precursor materials including RhCl3 ⋅ 3H2O, Rh(NO3)3 ⋅ 2H2O, Rh6(CO)16, [Rh(OCOCH3)2]2, and Rh2(SO4)3 have been compared as to their tendencies to produce upon reduction the various CO/Rh/Al2O3 species generally attributed to this catalytic system. The nitrate and carbonyl precursors are most easily reduced to rhodium metal. The acetate and sulfate anions poison the Rh/Al2O3 surface through decomposition during reduction leading to very minimal CO adsorption. The catalytic properties of Rh/Al2O3 could be quite dependent upon the nature of rhodium precursor chosen.