Platinum aluminophosphate oxynitride (Pt-AIPON) catalysts for the dehydrogenation of isobutane to isobutene

Abstract

The catalytic dehydrogenation of isobutane to isobutene over two series of platinum-supported aluminophosphate oxynitride (Pt-AlPON) catalysts, containing different amounts of nitrogen and synthesized using two different platinum precursors, was studied. The impregnation and platinum reduction processes result in a partial loss of nitrogen and a decrease in the specific surface area of the AlPON precursors. The surface and bulk structures of the catalysts are functions of the nitrogen content of the solid. At low nitrogen contents (less than or equal to 6% w/w), the nitrogen is found mainly on the surface of the catalyst as an -NHx species. Above 6% w/w, nitridation of the bulk begins. The basicity of the solids increases with increasing nitrogen content. The conditions under which synthesis takes place influence the final nitrogen content and the surface structure of the catalysts. Dehydrogenation of isobutane to isobutene of the Pt-AlPON catalyst correlates with the basicity of the catalysts. The surface structure of the solids also influences the yield of isobutene. (C) 2000 Academic Press.