Epoxidation of n-hexene and cyclohexene over titanium-containing catalysts |
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Authors: | Jie Bu Sam-Hun Yun Hyun-Ku Rhee |
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Affiliation: | (1) School of Chemical Engineering and Institute of Chemical Processes, Seoul National University, Kwanak-Ku, 151-742 Seoul, Korea |
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Abstract: | TS-1, Ti-beta and Ti-MCM-41 molecular sieves have been prepared by direct hydrothermal synthesis method and applied to the epoxidation of n-hexene and cyclohexene with H2O2 under mild conditions. Ti-beta with extremely low Al content was synthesized by using a seed method to suppress the formation of diol produced by Brønsted acid sites present in Ti-beta. It was also found that a large amount of by-products (1-ol and 1-one) formed over hydrophilic Ti-MCM-41. We further modified Ti-MCM-41 by silylation with bis(trimethylsilyl) trifluoroacetamide (BSTFA). Among these catalysts, the Ti-beta with low content of Al enhanced the yield of epoxide and suppressed the formation of diol markedly. The silylated Ti-MCM-41 reduced the formation of by-products and promoted the yields of epoxide significantly. Based on experimental results, a reaction mechanism with two parallel and competitive reactions was proposed. |
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Keywords: | TS-1 Ti-beta Ti-MCM-41 Epoxidation Silylation Br?nsted Acid Hydrophobic |
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