Propane dehydrogenation over Pt-Sn/Rare-earth-doped Al2O3: Influence of La, Ce, or Y on the formation and stability of Pt-Sn alloys

Abstract

In this study, La, Ce, or Y has been successfully incorporated into the gamma-Al2O3 framework to improve the Pt dispersion. Moreover, La and Y formed a dispersed phase, while a large portion of Ce constituted a separate phase on the Al2O3 support in the form of CeO2. The formation and stability of the Pt-Sn alloy in the catalysts were remarkably influenced by the addition of La, Ce, or Y. Compared to pure Al2O3 supports, La-doped Al2O3 promoted the formation of PtSn, while Ce- and Y-doped Al2O3 promoted the formation of PtSn2 alloy on reduced catalysts. However, the stability of Pt-Sn alloy during the reaction exhibited different tolerances according to the catalyst used. Compared to those of the Pt-Sn/Al and Pt-Sn/Y-Al catalysts, Pt-Sn/La-Al and Pt-Sn/Ce-Al catalysts showed superior catalytic performances and stabilities because of the lower coke contents, higher stabilities of PtSn and PtSn2 alloys, and smaller losses of Pt dispersion. This study suggests that the type and stability of Pt-Sn alloy formed on the Pt-Sn/support catalyst, which determined the catalytic performance and stability, were remarkably influenced by the support. (C) 2010 Elsevier B.V. All rights reserved.