The effects of calcination temperature of support on PtIn/Mg(Al)O catalysts for propane dehydrogenation reaction

The dehydrogenation of propane to propylene on bimetallic PtIn supported on calcined hydrotalcite, PtIn/Mg(Al)O-T, was investigated with the aim of understanding the effects of calcination temperature of hydrotalcite (MgAlO) on the structure/activity relationship of catalysts. The results showed that the highest catalysis reactivity and propylene selectivity were achieved over PtIn/Mg(Al)O-600 catalyst, which was improved obviously compared to our previous studies. The SEM images showed that all PtIn/Mg(Al)O-T catalysts had the flake structure collapsing constantly with the increasing calcination temperature of supports, which resulted in the change of textural properties of catalysts and the formation of more stable structure. Calcination temperature of support had obvious effect on the surface acid sites of PtIn/Mg(Al)O-T catalysts, and PtIn/Mg(Al)O-600 sample exhibited the lowest fraction of strong acid sites that were extremely unfavorable for facilitating propane dehydrogenation reaction. Besides, PtIn/Mg(Al)O-600 catalyst had the smallest average metal particle size as well as the largest specific surface area. XPS revealed that enhancing the interaction between indium and support was conductive to promoting the reduction of platinum. H2-TPR data suggested that the low-temperature reduction peak of PtIn/Mg(Al)O-600 was related to the unique catalytic behavior in the initial stage of propane dehydrogenation reaction. It can be concluded that PtIn/Mg(Al)O-600 catalyst possessed the largest surface area, the lowest fraction of strong acidic sites and In0 species, the best reducibility and distribution of Pt particles with the smallest Pt particle size, and the lowest coke amount corresponding to the best catalytic performance.