Preparation method of silicoaluminophosphate molecular sieve with hierarchical pore structure

Abstract

The invention provides a preparation method of a silicoaluminophosphate molecular sieve with a hierarchical pore structure. The method comprises the steps: firstly, by adopting tetraethyl orthosilicate or silica sol as a silicon source, pseudo-boehmite or aluminum isopropoxide as an aluminum source, orthophosphoric acid as a phosphorus source, and triethylamine, tetraethylammonium bromide or tetraethylammonium hydroxide as a template agent, uniformly stirring the silicon source, the aluminum source, the phosphorus source, the template agent and deionized water, performing hydrothermal crystallization treatment, and then centrifuging to obtain supernatant liquor; secondly, uniformly stirring the silicon source, the aluminum source, the phosphorus source, the template agent and the supernatant liquor, performing hydrothermal crystallization treatment, and filtering to obtain a filter cake and filtrate; thirdly, sequentially washing, drying and roasting the filter cake, and naturally cooling to obtain the silicoaluminophosphate molecular sieve with the hierarchical pore structure. The prepared silicoaluminophosphate molecular sieve provided by the invention has an obvious hierarchical pore structure, greatly shortens the diffusion path, improves the acid site accessibility, significantly prolongs the service life, and has very important practical values in reaction of preparing olefin from methanol.

Description

technical field [0001] The invention belongs to the technical field of molecular sieve synthesis, and in particular relates to a preparation method of a silicoaluminophosphate molecular sieve with a hierarchical pore structure. Background technique [0002] United Carbide Corporation (UCC) invented the silicoaluminophosphate molecular sieve (SAPO molecular sieve) with a pore size of about 0.4nm in 1984. SAPO molecular sieves have AlO linked by oxygen atoms 4 , SiO 4 and PO 4 Tetrahedral network, the pores in the crystal are due to Si 4+ replace P 5+ or Al 3+ The acidity produced or replaced by metals makes the molecular sieve play an important role in the catalysis of methanol to light olefins (MTO). Silicoaluminophosphate molecular sieve is another kind of molecular sieve catalytic material besides silica-alumina molecular sieve, which has been widely used in petrochemical and petroleum processing. The crystal of the SAPO-34 molecular sieve is similar to chabazite, w...

AI Technical Summary

Problems solved by technology

However, the preparation of mesoporous molecular sieve materials by post-treatment will reduce the acidity of the catalyst, and at the same time, it is easy to form mesoporous channels that cannot penetrate the entire catalyst.

However, the use of hard templates or soft templates to synthesize hierarchical porous molecular sieves is difficult to achieve industrialization due to the high cost of templates.

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