Method for synthesizing SAPO (silicoaluminophosphate)-34 molecular sieve by pre-processing silicon source through phosphoric acid

Abstract

The invention provides a method for synthesizing a SAPO (silicoaluminophosphate)-34 molecular sieve by pre-processing a silicon source through phosphoric acid. The method adopts the phosphoric acid as the phosphorus source, adopts the pseudo-boehmite as the aluminum source, adopts the silica sol as the silicon source, and adopts the triethylamine as the template; and the method comprises the following steps: pre-heating the silicon source by phosphoric acid at 200 DEG C for 3-4 hours; preparing the synthetic gel from the mixture of the aluminum source, the phosphorus source and the silicon source, the organic template and water, wherein the molar ratio of Al2O3 to H3PO4 to SiO2 to R to H2O is 1.0:2.0(0.05-2.0):3.0(50-200); hydrothermally crystallizing the synthetic gel at 200 DEG C under the self-generated pressure for 1-2 days; and then cooling, washing with water, separating and drying at room temperature to obtain the product. The SAPO-34 molecular sieve product of which silicon is more uniformly distributed can be obtained by using the method disclosed by the invention.

Description

technical field [0001] The invention relates to the synthesis of silicoaluminophosphate molecular sieve SAPO-34. Specifically, the silicon source is first heat-treated with phosphoric acid, and then triethylamine is used as a template to synthesize the SAPO-34 molecular sieve with uniform silicon distribution. Background technique [0002] Silicoaluminophosphate molecular sieve SAPO-34 made of PO 4 , AlO 4 and SiO 4 The tetrahedron constitutes a three-dimensional framework structure, and the SAPO-34 molecular sieve has a medium-strength acid center and an eight-membered ring microporous structure, which shows excellent catalytic performance in the reaction of methanol to light olefins. [0003] However, in the SAPO-34 molecular sieve synthesis system, the solubility of the silicon source is relatively poor, especially when the silicon content is high, the silicon component is easy to enter the SAPO-34 molecular sieve structure in the form of "silicon islands" of different ...

AI Technical Summary

Problems solved by technology

[0003] However, in the SAPO-34 molecular sieve synthesis system, the solubility of the silicon source is relatively poor, especially when the silicon content is high, the silicon component is easy to enter the SAPO-34 molecular sieve structure in the form of "silicon islands" of different sizes, making It is difficult to control the content and shape of the silicon component entering the SAPO-34 molecular sieve, resulting in uneven distribution of the silicon component, resulting in unstable catalytic performance of the SAPO-34 molecular sieve

Images