Synthesis method of SAPO-34 molecular sieve with large specific surface area

Abstract

The invention discloses a synthesis method of an SAPO-34 molecular sieve with a large specific surface area. The synthesis method comprises the steps as follows: (1) an aluminum source and water are mixed and pulped, tetraethylammonium hydroxide is added, the mixture is stirred, and a solution A is formed; (2) phosphoric acid, acidic silica sol and water are mixed to form a solution B; (3) the solution A and the solution B are subjected to parallel mixing, a mixed solution formed through parallel mixing is stirred in real time, the pH of the system is adjusted to 5.5-7.5, stirring is performed, and gel is obtained; (4) the gel is dewatered and dried, and a precursor is obtained; (5) the precursor is ground, the ground precursor is placed at the upper part of a reaction kettle, water is putin the lower part of the reaction kettle, and crystallization is performed; and (6) filtration is performed, filter residues are dried and calcined, and the SAPO-34 molecular sieve is synthesized. The prepared SAPO-34 molecular sieve is formed by polymerization of crystal grains of 50-200 nm, has the larger specific surface area and higher mesoporous capacity, contributes to quick access of reaction substances into pores and can improve the catalytic activity.

Description

technical field [0001] The invention belongs to the technical field of molecular sieves, in particular to a method for synthesizing SAPO-34 molecular sieves with high specific surface area. Background technique [0002] The unique structure of SAPO-34 molecular sieve makes it exhibit excellent catalytic performance in the reaction of methanol to light olefins and nitrogen oxides. However, the SAPO-34 molecular sieve has small pores, and the product is not easy to diffuse out, and it is easy to cause secondary reactions and carbon deposition, resulting in rapid deactivation of the catalyst. [0003] The pore structure and specific surface area of ​​the catalyst are important factors affecting the catalytic activity and service life of the catalyst. Increase the connectivity of molecular sieve channels and increase the specific surface area of ​​molecular sieves, especially the specific surface area of ​​mesopores, which can effectively reduce the residence time of reaction m...

AI Technical Summary

Problems solved by technology

However, these preparation methods often have problems such as cumbersome preparation methods, high cost, easy collapse of pores, and limited increase in specific surface area and pore volume.

Images