Propane dehydrogenation on PtSn/ZSM-5 catalyst: Effect of tin as a promoter

PtSn/ZSM-5 catalyst with different amounts of Sn was prepared for propane dehydrogenation. It was found that the addition of Sn not only had “geometric effect”, thus decreasing the size of the surface Pt ensembles, but also changed the interfacial character between metal and support. The presence of Sn could facilitate the transfer of the carbon deposits from the active sites to the carrier, which in consequence improved the catalytic stability. Suitable concentration of Sn on PtSn/ZSM-5 catalyst was preferable for the reaction. With the continuous addition of Sn, more amounts of Sn0 species could be formed, which was disadvantageous to the reaction. Compared to PtSn/γ-Al2O3, the capacity of the catalyst that supported on ZSM-5 zeolite to accommodate the coke was much better. The possible reason may attribute to the larger surface area and the particular character of the channels of ZSM-5 zeolite.