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SiO2-Modified Pt/Al2O3 for Oxidative Dehydrogenation of Ethane: A Preparation Method for Improved Catalytic Stability, Ethylene Selectivity, and Coking Resistance

Xi, Yanyan, Xiao, Jianmei, Lin, Xufeng, Yan, Weining, Wang, Chuangye, Liu, Chenguang
Industrial & engineering chemistry process design and development 2018 v.57 no.31 pp. 10137-10147
Bronsted acids, aluminum oxide, catalysts, catalytic activity, dehydrogenation, ethane, ethylene, nanoparticles, oxidation, process design, silica, silicon, temperature
A SiO₂-modified Pt/Al₂O₃ catalyst (SiO₂/Pt/Al₂O₃) was synthesized with a solution-based method using Pt/Al₂O₃ as the starting catalytic material and tetraethoxysilane (TEOS) as the Si precursor. The modification process can be conducted with several cycles. Each of the modification cycles included sequentially an evacuation step at an elevated temperature and an impregnation step followed by a solution-treatment step. The introduced SiO₂ layer showed an obvious sintering-resisting effect for the Pt nanoparticles at a high temperature of 600 °C. When used for catalytic oxidative dehydrogenation of ethane (ODHE), SiO₂/Pt/Al₂O₃ presented a significantly improved catalytic stability and coking depression compared to the unmodified Pt/Al₂O₃. Furthermore, the introduced SiO₂ layer helped improve the ethane conversion slightly and the selectivity to ethylene mildly. The improved selectivity to ethylene could be associable with the Brönsted acid sites brought by the SiO₂ layer as well as site distribution of the exposed Pt surface.