A kind of beta/mcm‑56 composite molecular sieve with core-shell structure and preparation method thereof

Abstract

The invention discloses a Beta / MCM-56 composite molecular sieve with a core-shell structure and a preparation method thereof. The molecular sieve uses Beta molecular sieve as the core phase, MCM-56 molecular sieve as the shell layer, and the size of the core phase is 0.3-3.0 μm, preferably 0.7 -2.0 μm, the thickness of the shell is 0.1-6.0 μm, preferably 0.3-5.0 μm, based on the weight of the composite molecular sieve, the shell content is 35%-90%, preferably 50%-80%. The preparation method is as follows: first, the surface of Beta molecular sieve is modified by plasma, and then Beta / MCM-56 core-shell composite molecular sieve is prepared by using it as the crystal nucleus. It has a good application prospect in the alkylation reaction.

Description

technical field [0001] The invention belongs to the field of preparation of inorganic materials, and in particular relates to a Beta / MCM-56 composite molecular sieve with a core-shell structure and a preparation method thereof. Background technique [0002] The topological type of MCM-56 molecular sieve is MWW, which belongs to the same type of molecular sieve material as MCM-22 and MCM-49. They have good application prospects in the alkylation reaction of olefins and benzene. Beta molecular sieves are also widely used in the production of cumene by alkylation of propylene and benzene. If MCM-56 and Beta molecular sieves with unique properties are organically compounded, and the compound crystal is endowed with reasonable acid distribution and good shape selectivity, and learn from each other, it can make full use of the shape selectivity and stability of MCM-56 molecular sieve And the advantages of high activity of Beta molecular sieve may have a special synergistic cataly...

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Problems solved by technology

The degree of compounding of the composite molecular sieve obtained by this method is not easy to control, and a large amount of Beta and Y type molecular sieves do not form a core-shell structure

[0006] The preparation of the above-mentioned composite molecular sieves is basically the improvement of the two-step crystallization method for synthesizing composite molecular sieves with a core-shell structure by means of chemical treatment, and there are still various deficiencies.

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