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Synthesis, Characterization And Catalytic Performance Of Phase-transfer Catalyst Based On Polyoxometalates

Posted on:2010-04-25Degree:MasterType:Thesis
Country:ChinaCandidate:H HuaFull Text:PDF
GTID:2121360275995447Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
Polyoxometalates have received more and more attention in the area of catalysis, because they are economical,environmentally friendly catalysts,and their acidic and redox properties can be controlled at atomic or molecular levels.Therefore, polyoxometalates are capable of epoxidizing a broad of olefins.This paper reported green H2O2-based epoxidation systems with three kinds of polyoxometalates.The main progress and research results have been obtained as follows:1.A halide-free reaction-controlled phase transfer catalytic system consisting of [π-C5H5N(CH2)15CH3]3PMoW3O24/H2O2/Ethyl acetate was developed,and could efficiently catalyze many kinds of alkenes epoxidation in high yield with the environmentally benign character.The catalyst could be easily recovered and reused after reaction.The fresh catalyst and used one were characterized by Raman,IR,31p MAS NMR and 31P NMR.2.We reported a new peroxotungstate[(CH3)2N((CH2)17CH3)2]2[W2O18],which was synthesized and used as temperature-controlled phase transfer catalyst for epoxidation of alkenes with H2O2 as the oxidant and dioxane as the solvent.This system can be used for homogeneous catalytic epoxidation of olefins under high reaction temperature and exhibits high conversion and selectivity.After reaction,with the temperature dropping,the catalyst can be precipitated from solvents and reused just like a heterogeneous catalyst.Even after 9 consecutive recycling reactions,no obvious activity loss was observed.3.A new environmentally friendly catalytic system "[C4mim][PW12O40]/H2O2/ Ionic liquids" was reported,and could catalyze epoxidation of 1-octene with 99% yield.The catalyst could be easily recovered and reused,and after 10 consecutive recycling reactions,no obvious activity loss was observed.However,epoxidation of other olefins have to be improved.
Keywords/Search Tags:Polyoxometalates, Olefins, Epoxidation, Hydrogen peroxide, Phase transfer catalysis
PDF Full Text Request
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