Non-oxidative dehydrogenation of propane to propene over Pt-Sn/Al2O3 catalysts: Identification of the nature of active site

•Synthesis methods effectively control the interaction of Pt and Sn in Pt-Sn/Al2O3.•Pt-Sn chloride complexes promotes the formation of PtSn alloy.•Sequential impregnation method induces Sn modification to Pt NPs.•Pt partially modified with reduced Sn is more active and stable for PDH reaction. Supported platinum-tin over various oxide supports have been widely recognized as the efficient propane dehydrogenation catalysts due to their excellent activity, C3H6 selectivity and stability after oxidative regeneration. The nature of the active species of the Pt-Sn catalysts is still under debate. Here, by controlling the formation of Pt-Sn chloride complexes during the impregnation stage, we managed to tune spatial distribution of Pt and Sn species over Al2O3 and further influence the degree of alloying between reduced Pt and Sn. The structure characterization revealed the co-impregnation method tend to generate PtSn alloy active site, while sequential impregnation of Pt on pre-synthesized Sn/Al2O3 tend to form Sn partially modification of Pt. Performance evaluation demonstrated that the Pt clusters partially modified by reduced Sn exhibited much higher activity and longer life-time than PtSn alloy counterparts under similar C3H6 selectivity. With further optimization, the Pt-Sn/Al2O3 prepared by sequential impregnation method achieved over 64.1 μmol/gcat/h propylene formation rate at the 30% propane conversion with the C3H6 selectivity exceeding 99%.