Promotion of the propane ODH reaction over supported V 2O 5/Al 2O 3 catalyst with secondary surface metal oxide additives

Abstract

Supported vanadia–alumina catalysts modified with chromium, molybdenum, and tungsten oxides were synthesized, characterized, and studied for their reactivity in the oxidative dehydrogenation (ODH) of methanol and propane. Raman and temperature-programmed reduction characterization studies revealed that only surface metal oxide species are present and that the modifiers are noninteracting in nature. Methanol ODH studies demonstrated that the modifiers cover the support acidic surface sites, are noninteracting in nature, and do not affect the surface vanadia redox product yield. The propane ODH reaction, however, revealed that the propylene yield increases when the surface MoO x and WO x are added to the supported vanadia–alumina catalysts. The surface MoO x and WO x modifiers are themselves relatively inert and appear to promote the propane adsorption step during the propane ODH reaction. The surface CrO x modifier is more active than the surface vanadia sites for propane activation, but has a lower selectivity for propane ODH to propylene.