Synthesis method of SAPO-34 molecular sieve

Abstract

The invention discloses a synthesis method of an SAPO-34 molecular sieve. The method includes the following steps of: (1) uniformly mixing a template agent, aluminum source, silicon source and water to obtain mixed liquid; (2) adding the solid-state seed crystal of raw powder of the SAPO-34 molecular sieve not less than 0.1 time of the mass of SiO2 in the silicon source to the mixed liquid obtained in the step (1) and mixing uniformly to obtain mixed liquid; (3) adding phosphorus source to the mixed liquid obtained in step (2) and mixing uniformly to obtain mixed liquid; (4) filling the mixed solution obtained in step (3) in a crystallization kettle and crystallizing at crystallization temperature; and (5) conducting centrifugal separation and filtration of the crystallized mixed solution and finally obtaining SAPO-34 raw powder after drying solid samples. The method mainly solves the problems of high cost of catalyst preparation and serious pollution caused by large amount of the template agent used for synthesizing the SAPO-34 molecular sieve in the prior art.

Description

technical field [0001] The invention relates to a preparation method of a SAPO molecular sieve, in particular to a method for synthesizing a SAPO-34 molecular sieve by using a seed crystal method to reduce the dosage of a template agent. Background technique [0002] SAPO-34 molecular sieve is a member of the SAPO-n series molecular sieve first synthesized by United Carbide Corporation (UCC) in 1982 (US4440871). Due to its suitable proton acidity, suitable pore structure, large specific surface area, good adsorption performance, good thermal stability and hydrothermal stability, etc., it is relatively suitable as a catalyst for the reaction of methanol to olefins. Good catalytic activity and selectivity. Usually SAPO-34 molecular sieves are prepared by hydrothermal crystallization with an appropriate amount of template agent, silicon source, aluminum source, phosphorus source, etc. As a structure-directing agent, the template agent is beneficial to guide the formation of t...

AI Technical Summary

Problems solved by technology

For SAPO molecular sieves, Liu Hongxing et al. provided in the patent CN101284673 a method of adding small crystal seeds with an average crystal size of less than 1 micron to the crystallization solution, which solved the problems of slow crystallization speed and low production capacity, but in No exploration has been made to reduce the amount of template agent. Although this method effectively shortens the crystallization time, it does not solve the problem of the amount of template agent used.

However, in the field of SAPO molecular sieve synthesis, the introduction of seed crystals to participate in the synthesis to reduce the amount of template used has not yet been reported.

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