Preparation of a rhodium catalyst from rhodium trichloride on a flat, conducting alumina support studied with static secondary ion mass spectrometry and monochromatic x-ray photoelectron spectroscopy

A Rh catalyst was prepd. by electrostatic adsorption of RhCl3-derived species in aq. soln. on a model support, consisting of a 4-5 mm thick layer of Al oxide on an Al foil. The conversion of the Rh precursor species into metallic Rh was studied by monochromatic XPS and static SIMS. Freshly prepd. catalysts contain adsorbed Rh-complexes with only one chloro ligand; this is explained by a mechanism in which chloro ligands of the initially adsorbed complex, [RhCln(OH)4-n(H2O)2]-, are displaced by surface OH groups. The Rh-Cl species decomp. at redn. temps. 200 Deg are needed to remove Cl from the alumina support. [on SciFinder (R)