MFI type molecular sieve catalyst with framework tungsten atoms and preparation method and catalytic application thereof

Abstract

The invention relates to an MFI type molecular sieve catalyst with framework tungsten atomsand a preparation method and a catalytic application thereof. The preparation method comprises the followingsteps: dropwise adding a silicon source into a structural guiding agent aqueous solution to form a clear solution A; and dropwise adding a tungsten source aqueous solution or a tungsten source into the solution A and carrying out hydrothermal crystallization at 110-150 DEG C for 48-120 h to obtain the MFI type molecular sieve catalyst with framework atomic atoms. The amygdaloidal MFI type molecular sieve nanoparticles containing framework tungsten atomsare prepared by means of a hydrothermal synthetic method in one step and the preparation process is simple and the condition is mild. The MFI type molecular sieve catalyst has relatively small particle size, so that the material diffusing path is shortened, mass transfer is facilitated, and problems that reactants and product molecules are not favorably diffused in the ducts as a result of the relatively long diffusing path of the conventional MFI type molecular sieve are solved. By introducing the framework atomic atoms, the molecular sieve has a catalytic oxidizing action to tungsten, and can be applied to catalyzing epoxidation reaction of cycloolefin.

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.

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