Abstract
Pentacoordinate Al(3+) (Al(3+) (penta)) sites on alumina (Al(2)O(3)) could anchor and stabilize the active site over the catalyst surface. The paper describes the specific effect of Al(3+) (penta) sites on the structure and the catalytic performance of Al(2)O(3) supported Pt catalysts by modulating the quantity of Al(3+) (penta) sites. The Al(3+) (penta) site content of Al(2)O(3) 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(3+) (penta) sites over the Al(2)O(3) support. We further find that, when the calcination temperature of the impregnated Al(2)O(3) is higher than the calcination temperature of Al(2)O(3) precursor, the structural rearrangement of Al(3+) (penta) sites could make Pt partially buried in Al(2)O(3). 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(3+) (penta) site over Al(2)O(3) support.