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Enhancing ethylene epoxidation of MWW-type titanosilicate/H2O2 catalytic system by fluorine implanting

Abstract

Fluorine-implanted titanosilicate Ti-MWW, with a greatly enhanced catalytic performance in the liquid-phase epoxidation of ethylene with aqueous hydrogen peroxide, has been post-synthesized by fluorinating conventional Ti-MWW with NH4F. The effects of fluorination conditions, such as solvent, NH4F addition amount and temperature, on the zeolite structure and the catalytic performance of the resultant fluorine-implanted Ti-MWW were investigated in detail. Methanol proved to be a better solvent for fluorination than water in terms of preserving the crystalline structure and improving the selective epoxidation activity. Fluorine-implanting generated the SiO3/2F species in the framework to increase the electropositivity of the tetrahedral Ti active sites. A stronger hydrogen-bonding was thus formed between the Hend in Ti-Oα-Oβ-Hend intermediates and the adjacent Si-F species, which were helpful to significantly increase the catalytic activity in the epoxidation of ethylene with H2O2. In addition, the fluorination also generated the secondary mesopores useful to improve the accessibility of the active sites, making the fluorine-implanted Ti-MWW catalyst possess better reusability than the parent one.

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Publication details

The article was received on 06 Mar 2017, accepted on 15 May 2017 and first published on 16 May 2017


Article type: Paper
DOI: 10.1039/C7CY00428A
Citation: Catal. Sci. Technol., 2017, Accepted Manuscript
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    Enhancing ethylene epoxidation of MWW-type titanosilicate/H2O2 catalytic system by fluorine implanting

    X. Q. lu, W. Zhou, Y. J. Guan, A. Liebens and P. WU, Catal. Sci. Technol., 2017, Accepted Manuscript , DOI: 10.1039/C7CY00428A

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