NMR characterization of the supported 12-heteropoly acids

Abstract

Catalysts have been prepared by the incipient wetness method and characterized by ³¹P MAS NMR spectroscopy. Two species, i.e. the interacting molecular and the crystalline, were found in both the supported PMo₁₂ and supported PW₁₂ catalysts. Experimental results indicated that the interacting species are more thermally stable and resistant to water etching than the crystalline species. Furthermore, the interacting species also exhibited an extremely good selectivity in propan-2-ol dehydration and in the esterification of acetic acid with ethanol. The electronic properties of the interacting species were found to be support dependent.