QD180 : Preparation and Characterization of Hetropoly_Acids Supported on Functionalized Nano_Boehmit and Investigation of Their Catalytic Application
Thesis > Central Library of Shahrood University > Chemistry > MSc > 2013
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Abstarct: Heteropolyacids are a class of polyoxomextalates which their countercations was replaced by protons. Among numerous applications of heteropoly acids, homogenous catalysis is by far the most important. The oxidation and acidic properties of polyoxomextalates are of great importance in catalysis, because these properties could be controlled at atomic or molecular levels. More ever, surface area is an important property for catalytic systems and unfortunately it is very low for heteropolyacids (1-5 m2/g). So supporting the heteropolyacids on solid beds with high surface area could improve their catalytic properties in various catalytic system. In present study nanoboehmite with high surface area (326 m2/g) and high degree of surface hydroxyl groups was prepared via hydrothermal assisted sol-gel processing of aluminium 2-butoxid, as catalytic bed. Then, this inorganic bed was covalently functionalized with 3-(tri-methoxysilyl)propyl amine (AFNB). The AFNB was then supported with some of keggin heteropolyacids (HPA/AFNB) and they were caractrized by FT-IR, UV-Vis, XRD and ICP techniques. In this researche, the catalytic properties of HPA/AFNB were investigated in epoxidation of various olefins with TBHP. The catalytic procedure was optimized for different parameters. It was found that the optimized condition with over 98% yield for epoxidation of cis-cyclooctene in the presence of PMo/AFNB was 25mg of catalyst, 0.5 ml CCl4 as solvent, and 1.12 mmol t-butyl-hydro-peroxide as oxidant at 77ºC after 15 min. . In addition, recycling experiments revealed that the nano-catalyst can be repeatedly applied for nearly complete epoxidaton of alkenes for at least five successive cycles. SiMo/AFNB catalysts has been showed lower catalytic activity and it was achived 98% yield after 30 min. HPA/AFNB catalyst was also used for transestrification of Sunflower oil and EtOH. Some characterestic properties of the product were analyzed and compared to Standard samples.
Keywords:
#Heteropolyacid #Nano-Boehmite #Epoxidation #Transestrification Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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