A kind of MFI type molecular sieve catalyst with skeleton tungsten atom and preparation method and catalytic application

Abstract

An MFI molecular sieve catalyst with skeleton tungsten atoms and its preparation method and catalytic application, adding silicon source dropwise to the structure directing agent aqueous solution to form a clear solution A; adding the tungsten source aqueous solution or tungsten source to the A solution dropwise, Then hydrothermally crystallize at 110° C. to 150° C. for 48 hours to 120 hours to obtain an MFI type molecular sieve catalyst with skeleton tungsten atoms. The invention adopts a hydrothermal synthesis method to prepare almond-shaped MFI molecular sieve nanoparticles containing skeleton tungsten atoms in one step, and the preparation process is simple and the conditions are mild. Its smaller particle size shortens the material diffusion path and is more conducive to mass transfer, which largely solves the problem that the long diffusion path of conventional MFI-type molecular sieves is not conducive to the diffusion of reactants and product molecules in its pores. And other issues. Due to the introduction of tungsten heteroatoms in the framework, this type of molecular sieve has the catalytic oxidation effect of tungsten, and can be used in the epoxidation reaction of catalyzed cycloolefins.

Description

technical field [0001] The invention relates to a preparation method of a catalyst, in particular to an MFI type molecular sieve catalyst with skeleton tungsten atoms, a preparation method and a catalytic application. Background technique [0002] ZSM-5 is a molecular sieve with MFI-type pore structure, and its skeleton structure contains two intersecting ten-membered ring pore systems. One is an S-shaped curved 10-membered ring channel with a corner of about 150° and a pore size of 0.55nm×0.51nm, and the other is a linear 10-membered ring channel with a pore size of 0.53nm×0.56nm. Because of its unique shape selectivity and acidity, ZSM-5 molecular sieve is one of the most important molecular sieve catalytic materials at present, and is widely used in catalytic fields such as petroleum processing, coal chemical industry and fine chemical industry. [0003] Literature (Robson H.Verified Syntheses of Zeolitic Materials.2 nd Ed.Amsterdam: Elsevier, 2001: 199.) with NaOH, TPA...

AI Technical Summary

Problems solved by technology

In the prior art, the impregnation method is used to load tungsten on the Al-ZSM-5 molecular sieve, which is only a modification of the molecular sieve. The tungsten species does not enter the molecular sieve skeleton, but is coated on the surface of the ZSM-5 molecular sieve, and is calcined at high temperature. It is easy to cause tungsten sublimation loss in the process

[0010] At present, there is no literature report on the use of W-containing molecular sieves in the epoxidation of macromolecular cycloolefins.

Images