Propane dehydrogenation over PtSnNa/La-doped Al₂O₃ catalyst: Effect of la content

La-doped mesoporous alumina (La-Al) with different content of La was synthesized and then this kind of material was used as the support for platinum-tin catalyst in propane dehydrogenation. It was found that a portion of La had been incorporated into the alumina framework with La-doping. When the content of La in the support was suitable, both the catalyst acidity and the coke amount were decreased. Moreover, in these cases, the presence of La could not only promote the distribution of metallic particles, but also strengthen the interaction between tin species and support. As a result, more amounts of tin could exist in oxidized states, which was beneficial to enhance the interaction of Pt with SnO_x species and the reaction activity. In the current study, the PtSnNa/La-Al catalyst with 1.0 wt.% La exhibited the best catalytic activity and stability. Compared with pure Al₂O₃ support, this La-doped Al₂O₃ support was also favorable for the improvement of the catalytic performance even at higher reaction temperature (605 C). However, with the excessive addition of La, the agglomerations of metallic particles and the increase in percentage of metallic tin (Sn ⁰) on the catalyst were found, which seriously resulted in the deactivation of catalyst.