The role of pentacoordinate Al sites of Pt/AlO catalysts in propane dehydrogenation.

Pentacoordinate Al (Al ) sites on alumina (AlO) could anchor and stabilize the active site over the catalyst surface. The paper describes the specific effect of Al sites on the structure and the catalytic performance of AlO supported Pt catalysts by modulating the quantity of Al sites. The Al site content of AlO exhibits a volcano-type profile as a function of calcination temperature due to the structural rearrangement. The loading of Pt and subsequent calcination can consume a significant portion of Al sites over the AlO support. We further find that, when the calcination temperature of the impregnated AlO is higher than the calcination temperature of AlO precursor, the structural rearrangement of Al sites could make Pt partially buried in AlO. Consequently, this partially buried structure leads to relatively low conversion but high stability for propane dehydrogenation. This work further elucidates the stabilization mechanism of the Al site over AlO support.