MFI molecular sieve and preparation method and application thereof

Abstract

The invention discloses an MFI molecular sieve and a preparation method and application thereof, two kinds of metal heteroatoms of titanium and vanadium are doped into an MFI skeleton at the same time, a structure regulator is added, and a coupled and coordinated catalytic active site structure is formed between adjacent skeleton titanium and skeleton vanadium active centers through guiding, and the titanium and vanadium doped MFI molecular sieve containing the coupled coordination structure is obtained. The prepared MFI molecular sieve is mixed with cyclohexene, acetonitrile and hydrogen peroxide, the coupling coordination active site between framework titanium and framework vanadium in the MFI molecular sieve can efficiently catalyze hydrogen peroxide molecules to form an active matter, the active matter attacks a cyclohexene C = C bond, electrophilic addition is carried out, oxygen atoms are transferred, and cyclohexene oxide is generated. In the preparation of cyclohexene oxide, the prepared MFI molecular sieve is used as a catalyst so that the conversion rate of cyclohexene and the selectivity of cyclohexene oxide can be improved, and the reaction time is shortened.

Description

technical field [0001] The invention relates to the field of catalytic materials, in particular to an MFI molecular sieve and its preparation method and application. Background technique [0002] Zeolite molecular sieves are a class of solid acid catalysts with regular microporous structures, and up to 248 crystal structures have been reported, among which the MFI (Mobil Five Instructure) topology has attracted extensive attention. The topological structure of MFI is a three-dimensional skeleton structure formed by the intersection of straight ten-membered ring channels and "Z"-shaped ten-membered ring channels. The synthesis of molecular sieves with MFI topological structure can be roughly summarized into the following three methods: hydrothermal synthesis method, solid phase conversion method, and dry gel conversion method. The heteroatoms successfully doped by the current preparation method of MFI molecular sieve include aluminum, titanium, iron, manganese, tin, vanadium...

AI Technical Summary

Problems solved by technology

Due to the pore size of the double ten-membered ring micropores of TS-1 molecular sieve is only 0.55nm, there is serious internal diffusion resistance, resulting in insufficient catalytic activity of TS-1 molecular sieve in the epoxidation reaction of macromolecular cycloolefins

Although the diffusion resistance in the nanosheet TS-1 molecular sieve has been greatly eliminated, only 24.0% cyclohexene can be catalytically converted within 2 hours of reaction time, indicating that the single active center skeleton titanium in the TS-1 molecular sieve has insufficient catalytic activity.

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