| During the process of propane dehydrogenation (PDH), catalyst deactivation is inevitable because of deep thermal cracking and coking at high temperature. The frequently regeneration of dehydrogenation catalysts leads to the sintering of Pt and, therefore, the catalyst lifetime. So, the high thermal stability is a key property for PDH catalyst.In this paper, two different morphology of Al2O3, dandelion-like Al2O3(PGY) and coral-like Al2O3(SH), were synthesized by solvent-thermal methods. A commercial Al2O3(SY) was also prepared by sol-gel method. These Al2O3 were used as the support for Pt. The physical and chemical properties of these samples were characterized by BET, TPR, SEM, TEM, STEM, XPS and CO chemi-sorption. Then, thermal stabilities of supported Pt were inspected through air aging test. Furthermore, La was tested as the modifier for the thermal stability. At last, catalysts with different Pt/Sn ratio were synthesized by incipient impregnation method. Catalytic performance and stability after catalyst regeneration of different PtSn catalysts for propane dehydrogenation were investigated.Two types of Pt particle size distributions on the Al2O3 surface after air aging at 600℃ in air was found on all three different Pt/Al2O3 catalysts:Pt particles with dimensions of 1-3nm and agglomerates about 50nm in size. Pt supported on SH-AI2l3 had the best thermal stability than the other two. After air aging, there were still half of Pt particles maintaining highly dispersed on Al2O3 surface, while for other samples, only about 20% of small Pt particles exist. The best Pt/Sn ratio on different Al2O3 supports were:PtSn3/SYã€PtSn2/PGY〠PtSnO.5/SH. PtSnO.5/SH had the best reaction activity and highest stability after three reaction-regeneration cycles. The results obtained in this work provided some insight of modification of Al2O3 support and maybe helpful for further development of high performance catalysts. |
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