Adsorption of Hexachloroplatinic Acid on γ-Alumina

Abstract

the surface is an important factor for the meso-and macroporous materials. Generally the sulfur adsorption and activity are low as in the case of SiCL, MgO, and carbon blacks. The presence of Lewis acid sites of the surface of ALO;s and TiCL may enhance sulfur adsorption and thereby the activity. These acid sites can be poisoned with Lewis bases such as water or pyridine.Iron oxide shows exceptional behavior, because it combines a high activity with a very low selectivity. An oxidation-reduction mechanism involving the iron ion is very likely. Other investigators (Cook and Ross, 1973;Ross and Jeanes, 1974) found that the oxides of Co, Mo, Ni, and W also promote the direct conversion of HL> S in SCL.

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

“…At low pH, alumina dissolves in the solution. The dissolved species can readsorb on the support, possibly after reaction with Rh complexes [28]. Already adsorbed Rh complexes may be covered by redeposited alumina.…”

Transformations of γ-alumina in aqueous suspensions

“…According to most authors, a hydrated layer of hydroxide Al(OH) 3 forms at the surface of γ -Al 2 O 3 after the oxide is suspended in an aqueous solution, without dissolution of the support [17,18]. Actually, Eng et al [19] have shown with the help of a surface diffraction technique (crystal truncation rod diffraction) that the (0001) single-crystal surface of α-Al 2 O 3 in ambient air is intermediate between the bulk structure of α-Al 2 O 3 and gibbsite Al(OH) 3 .…”

Kinetics of dissolution of alumina in acidic solution

“…The interaction of alumina with acids is encountered in the preparation and regeneration of certain types of catalysts. For example, in studies of the preparation of Pt/AI,O, catalysts, the interaction of hexachloroplatinic acid with alumina supports, and the influence of adding inorganic acids as coingredients to hexachloroplatinic acid impregnating solution have been investigated (Maatman et al, 1971;Santacesaria et al, 1977;Shyr and Ernst, 1980). Methods have been proposed for the removal of nickel and vanadium from contaminated Co/Mo/Al,O, hydrodesulfurization catalysts (Hernandez, 1982;Ganguli, 1984;Myerson and Ernst, 1985).…”