Fabrication of highly dispersed Pt-based catalysts on γ-Al_2O_3 supported perovskite Nano islands: High durability and tolerance to coke deposition in propane dehydrogenation

摘要

A series of novel gamma-Al2O3 supported Pt-In bimetallic catalysts were prepared by perovskite (PTO) lattice interstitial confined reduction and compared with industrial catalyst PtIn/gamma-Al2O3 in the propane dehydrogenation to propene. The physics-chemistry properties of all catalysts and precursors were characterized by BET, NH3-TPD, TPR, XRD, TEM, STEM-EDS, XPS, TG and O-2-TPO techniques. The results show that the metal ions of Pt4+ and In3+ confined in PTO lattice interstitial sites were more easily reduced than those confined in PTO lattice. The lattice interstitial confinement was beneficial for the formation of small and highly dispersed Pt-In bimetallic species on the surface of gamma-Al2O3 supported PTO Nano islands. It is just the confinement of PTO lattice interstitial sites for appropriate In3+/In-0 ratio and weak Pt-In interaction and the sharing Al-O bond for anchoring PTO nanoparticles and weakening the surface acid sites result in the high activity and superior stability of PtIn/LaAlO3/gamma-Al2O3 in propane dehydrogenation. The initial propane conversion of PtIn/LaAlO3/gamma-Al2O3 was 47%, and can be maintained at 25% after 16 h, while its propene selectivity only decreased from 96% to 90%.