FTIR study of the effects of water pretreatment on the acid sites and the dispersion of metal particles in Y zeolites and mordenites |
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| Institution: | 1. Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China;2. Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin, 300072, China;1. Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany;2. Technische Universität Chemnitz, 09107 Chemnitz, Germany;1. Zhejiang Provincial Key Lab for Chem. & Bio. Processing Technology of Farm Product, School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, 310023, PR China;2. Department of Applied Chemistry, Graduate School of Engineering, University of Toyama, Toyama, 9308555, Japan;3. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, PR China;1. Department of Pharmacology, Anhui Medical University, Hefei, China;2. Department of Anesthesiology, The Third Affiliated Hospital of Anhui Medical University, Hefei, China;3. Department of Pharmacy, The Third Affiliated Hospital of Anhui Medical University, Hefei, China |
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| Abstract: | FTIR results on zeolite-supported Pt and Pd show that the presence of water during metal reduction modifies both the acid and the metal functions of these catalysts. The water treatment eliminates Lewis acid sites and lowers the concentration of Brønsted acid sites by partial dealumination. At low temperature CO is adsorbed on Brønsted sites; the position of the corresponding FRIR band indicates that for Pt/HMOR, (MOR = mordenite) unlike Pt/HY, the intrinsic acid strength of these sites is increased by the wet reduction procedure. FTIR spectra after CO adsorption at room temperature show that wet reduction markedly improves the dispersion of Pt in HMOR; this effect is weaker for HY and absent for the Na forms of the zeolites. Bands of gem-Pt(CO)2, which are indicative of very small, possibly electron-deficient Pt clusters, are detected in Pt/HMOR. |
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