Preparation method of isomorphous-phase core-shell structured beta-molecular sieve

Abstract

The invention relates to a preparation method of an isomorphous-phase core-shell structured beta-molecular sieve, which is implemented by taking white carbon black, tetraethylortho silicate, sodium metaaluminate, tetraethylammonium hydroxide, and ammonium fluoride as raw materials and taking a tetraethylammonium hydroxide aqueous solution as a treating agent through the steps of synthesizing a nuclear-phase beta-molecular sieve firstly; carrying out mixed liquid preparation, and crystallizing the obtained object in a reaction kettle; and sequentially carrying out constant-temperature heating, quenching, cleaning and dispersing, centrifugal separation, vacuum drying, and high-temperature vacuum calcination on the obtained product, so that the isomorphous-phase core-shell structured beta-molecular sieve is obtained. The preparation method is advanced in process and detailed and accurate in data, the crystal diameter of the prepared isomorphous-phase core-shell structured molecular sieve is 15-20 mu m, the outside of each crystal is tightly wrapped with a nanocrystal, the wrapping degree of product reaches 97%, and the product purity reaches 99.9%, so that the molecular sieve can be matched with various chemical substances and then the obtained objects are used as catalysts, therefore, the method disclosed by the invention is an extremely ideal preparation method of an isomorphous-phase core-shell structured beta-molecular sieve.

Description

technical field [0001] The invention relates to a preparation method of a beta molecular sieve with an isomorphic core-shell structure, and belongs to the technical field of preparation and application of zeolite composite catalytic materials. Background technique [0002] β molecular sieve has a unique topological structure. It is a high-silicon molecular sieve with a three-dimensional twelve-membered ring channel structure. It has good thermal stability, hydrophobicity, acid resistance, and coking resistance. It is widely used in hydrocracking, hydrocarbons, etc. Isomerization, alkylation of aromatic hydrocarbons, catalytic process of automobile exhaust purification. [0003] In the catalytic process, the carbon on the surface area of ​​β molecular sieves is a main reason for its catalytic inactivation. At present, with the in-depth research on nanotechnology, nano-scale β molecular sieves have larger specific surface area, shorter pore structure and more It has a lot of ...

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Problems solved by technology

[0003] In the catalytic process, the carbon on the surface area of ​​β molecular sieves is a main reason for its catalytic inactivation. At present, with the in-depth research on nanotechnology, nano-scale β molecular sieves have larger specific surface area, shorter pore structure and more It has a lot of surface activity, so that it can well reduce or even eliminate the problem of carbon deposition, but there are still many shortcomings in the process of preparing nano-sized β molecular sieves, such as easy oxidation and moisture absorption, easy agglomeration, and poor stability; micron-sized large-grain β molecular sieves It can provide a longer diffusion path and regulate the catalytic reaction; the existing single-structure β molecular sieve has many disadvantages, which restricts its industrial application

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