Epoxidation of crotyl alcohol using Ti-containing heterogeneous catalysts: Comments on the loss of Ti by leaching

Davies, L. J., McMorn, P., Bethell, D., Bulman Page, P. C. B., King, F., Hancock, F. E. and Hutchings, G. J. (2001) Epoxidation of crotyl alcohol using Ti-containing heterogeneous catalysts: Comments on the loss of Ti by leaching. Journal of Catalysis, 198 (2). pp. 319-327. ISSN 0021-9517

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Abstract

The leaching of Ti from the redox molecular sieve TS-1 is compared and contrasted with Ti leaching from Ti-Al beta, Ti-MCM-41, and a Ti-xerogel under both batch and continuous flow reaction conditions for the oxidation of crotyl alcohol with hydrogen peroxide. The product distributions for the catalysts are similar, with epoxide being formed initially and, subsequently, the secondary reaction products of the trial and ether dials. Ti leaching is more pronounced under continuous flow conditions and the order of stability is TS-1 > Ti-Al beta > Ti-MCM-41 > Ti-xerogel, for both continuous flow and batch reaction conditions. TS-1 leaching is shown to be caused by the reaction of trial with TS-1 in the presence of hydrogen peroxide. A possible mechanism in which the triol byproduct chelates the Ti and breaks the Ti-O-Si framework bonds, leading in turn to the formation of a Ti species in solution, is proposed. The soluble Ti species is found to be an active homogeneous catalyst giving triol as the major product from crotyl alcohol. Under batch reaction conditions, it is possible that an equilibrium is established between the solution Ti species and Ti on the catalyst surface. This equilibrium is perturbed when continuous flow conditions are used, and this leads to increased Ti leaching. (C) 2001 academic Press.

Item Type: Article
Uncontrolled Keywords: containing,heterogeneous epoxidation,heterogeneous epoxidation using ti-xerogel,silica mixed oxides,framework,hydrothermal stability,using ti-mcm-41,hydrogen-peroxide,heterogeneous epoxidation using ti-beta,mcm-41,heterogeneous epoxidation using ts-1,ti-leaching,epoxidation of allylic alcohols,molecular-sieves,liquid-phase oxidations,metal-ions,titanium silicalite,zeolite-beta
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 21 Jun 2011 12:28
Last Modified: 07 Nov 2018 15:32
URI: https://ueaeprints.uea.ac.uk/id/eprint/32822
DOI: 10.1006/jcat.2000.3139

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