Catalytic Properties of Silica-supported 12-Molybdophosphoric Acid in the Conversion of 2-Propanol

Abstract

A technical silica gel was impregnated with a solution of the titled heteropoly acid (1–20 w/w%) and calcined at 400, 600 or 800 °C. Dehydration of the alcohol generally increased with the loaded acid, and decreased almost linearly with the reaction temperature (360–260°C). The best alcohol decomposition was achieved over the 600°C-calcined catalysts when over 90% conversion to propene was attained. The apparent activation energies decreased with the degree of loading and attained a value of 22 kJ/mol on the 600°C-calcined 20% HPMo-supported catalyst (half that on the solids calcined at 400°C and 800°C). The catalytic dehydration cannot be described by means of a proton-involved mechanism on the severely treated catalysts at ≥600°C. An outer surface mechanism might be effective involving terminal oxygens and MoV ions.