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Synthesis Of Immobilized Heteropolyphospatotungstate Catalysts And Its Activity In The Epoxidation Of Cyclohexene

Posted on:2011-01-05Degree:MasterType:Thesis
Country:ChinaCandidate:L L FuFull Text:PDF
GTID:2121330332958701Subject:Chemical processes
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In this work, chloromethylated polystyrene (chlorine ball) grafted quaternary ammonium heterophosphortungstate catalyst was prepared and used in the epoxidation of cyclohexene oxidized by hydrogen peroxide. The main aspects of work were carried out as follow:Improving the existing technology of the preparation of immobilized catalsts through the following aspects:1) adisuting the ratios of feeds, this could improve the efficiency of raws and reduce the cost of production significantly; 2) selecting acid A of C3 concentration as acidifie synthesized H2WO4. In this way, it simplified the experimental operation and also produced a quite special acid environment within the catalyst that enhanced its catalytic activity; 3) adisuting the quantity of H3PO4 and its feeding method, so the active component{PO4[WO(O2)2]4}3 could been prepared, and its quotiety of cross-linking was about 38%.Catalst was used in the epoxidation of cyclohexene, we could carry out quantitative analysis of the product through gas chromatography, by internal standard method, calculated based on cyclohexene. The equivalent coversion of cyclohexene was 85.5% with 95.4% selectivity of epoxycyclohexan. And the structures of the fresh and recycled were characterised by IR spectroscopy, that indicated there was not much formation of structural transformation. The catalyst can be recovered after reaction without any loss, and experiments showed that the catalyst could still maintain good catalytic activity after repeating used for 10 times.The main factors which sffected the epoxidation reaction were studied, such as amount of additive, the treatment of catalyst, reaction temperature, reaction time, and amount of catalyst. After optimization of reaction conditions, the proper technological conditions detailed as follows:without solvent, n(C6H10):n(H2O2)=1.75:1, hydrogen peroxide solution of 226.6g, catalyst of 32g, additives of 10.67g, reaction tempreature 60℃, reaction time 5.5h.Based on the experiments of preparation of catalyst and epoxycyclohexan, we designed amplification experiment to explore the preparation of immobilized catalysts and epoxycyclohexan. The result proved the feasibility of the two amplification, and that could provide the basis data for the industrialization of their preparation.
Keywords/Search Tags:quaternary ammonium heteropolyphosphatotungstate, immobilized, epoxycyclohexane, epoxidation
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