Topics in Catalysis 6 (1998) 87–99 87 Solid acid catalysts based on supported tungsten oxides

Supported WOx clusters are active and stable catalysts for isomerization, dehydration, and cracking reactions. Brønsted acid sites form on WOx clusters when a lower valent element replaces W6+ or when W6+ centers reduce slightly during catalytic reactions. WOx clusters of intermediate size provide the balance between reducibility and accessibility required to maximize the number of surface H+ species in WOx–ZrO2, zirconium tungstate, and oxygen-modified WC catalysts. H2 is involved in the generation and maintenance of Brønsted acid sites during catalytic reactions on WOx clusters