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Study On Styrene Epoxidation Over Supported Heterogeneous Catalyst

Posted on:2013-12-09Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y ShenFull Text:PDF
GTID:2251330401469836Subject:Chemical Engineering
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As the product of styrene epoxidation, styrene oxide is an important intermediate in organic synthesis, pharmaceutical and perfume industry. Epoxidation with molecular oxygen is the focus of epoxidation research in recent years but there will be diverse by-products in styrene epoxidation reaction like benzaldehyde and benzoic acid because of the activity of C=C double bond, and the low conversion and poor selectivity could be the main problems of this epoxidation. Hence, it is of great significance both in academic and practical aspect to design a new catalyst which could catalyze styrene eopxidation efficiently.This thesis is to develop heterogeneous catalysts that could be used in the reaction of styrene epoxidation with molecular oxygen. It focuses on the preparation, characterization and catalytic performance of the silicon supported cobalt catalyst, titanium silicalite supported cobalt catalyst and titanium silicalite supported gold catalyst. Outlined as follows:Co3O4/SiO2catalyst was prepared by deposition precipitation method using silica gel for support and characterized by ICP-AES, XRD and TEM. It exhibited catalytic activity in styrene epoxidation in the case of no solvent but with low conversion and polymerization of styrene after a given time.3%Co3O4/SiO2catalyst was found to be an efficient catalyst with77.5%conversion of styrene and54.6%selectivity of styrene oxide under the optimum reaction condition of catalyst0.11g, styrene1mL, DMF20mL, flow. rate of oxygen20mL/min,100℃and6h. Its catalytic performance was better than other cobalt catalysts under the same condition.Co3O4/TS-1catalyst was prepared by the same way using TS-1as support. Compared with the catalytic performance among Co3O4, TS-1and Co3O4/TS-1, it was noteworthy that there was a synergy between Co and Ti in the catalyst. Under the condition of catalyst0.11g, styrene1mL, DMF20mL, flow rate of oxygen20mL/min,100℃and8h, the styrene conversion increased to77.7%while the selectivity of styrene oxide was56.4%. The MFI topological structure made Co3O4highly decentralize on the surface of TS-1and the load efficiencies of the catalysts were more than95%.Au/TS-1catalyst showed good catalytic performance at low temperatures with17.4%conversion of styrene,26.7%selectivity of styrene oxide and65.3%selectivity of benzaldehyde under the reaction condition of70℃and5mL solvent. It was showed that the catalytic activity of Au/TS-1catalyst increased when the solvent amount decreased that was opposite to the performance on Co catalysts, this may be because the generation of benzoic acid could be efficiently inhibited by gold particles. Although it was found that the catalytic performance of Au/TS-1catalyst was mostly depended on the catalysis of TS-1, it was also true that the gold particles on the support could increased the epoxide selectivity remarkably, the catalysis of gold was well reflected.
Keywords/Search Tags:styrene epoxidation, styrene oxide, cobalt catalyst, gold catalyst, silicondioxide, titanium silicalite
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