Method for synthesizing SAPO-34 molecular sieve by using industrial phosphate fertilizer byproduct fluosilicic acid and application of SAPO-34 molecular sieve

Abstract

The invention provides a method for synthesizing an SAPO-34 molecular sieve by using an industrial phosphate fertilizer byproduct fluosilicic acid and application of the SAPO-34 molecular sieve, and belongs to the technical field of comprehensive utilization of resources. The method comprises the steps of 1) adding a phosphorus source and an aluminum source into water, stirring, and adding triethylamine to obtain a solution I; (2) mixing industrial fluosilicic acid and triethylamine to obtain a solution II, and adding the solution II into the solution I to obtain a precursor solution, wherein the molar ratio of Al2O3 to SiO2 to P2O5 to H2O to TEA in the precursor solution is 1: (0.3-0.6): (1-1.1): (70-90): (3.2-9.5); 3) performing hydrothermal crystallization on the precursor solution to obtain an SAPO-34 molecular sieve precursor; and (4) roasting the SAPO-34 molecular sieve precursor so as to obtain the microporous SAPO-34 molecular sieve. According to the application of the SAPO-34 molecular sieve, the SAPO-34 molecular sieve is loaded into a chromatographic column, crude phosphoric acid is added, reduced pressure suction filtration is carried out, and defluorination is conducted on the crude phosphoric acid. The prepared SAPO-34 molecular sieve is large in crystal grain, high in crystallinity, good in purity and less in impurity phase, the defluorination rate of crude phosphoric acid containing 6 g / L of fluorine can be 65% or above, and the fluorine adsorption capacity of the molecular sieve can reach 350 mg / g.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of resources, and in particular relates to a method for synthesizing SAPO-34 molecular sieves by utilizing fluosilicic acid, a by-product of industrial phosphate fertilizers, and an application thereof. Background technique [0002] During the production process of wet-process phosphoric acid and phosphate fertilizer, a large amount of fluorine-containing gas will be produced, which will form industrial fluosilicic acid after being absorbed by water. As a by-product of the development of the phosphate fertilizer industry, the output of fluosilicic acid in my country is huge, but it is usually only processed into products with small demand such as fluorine salts, and the abundant resources such as silicon, aluminum, and phosphorus have not been fully utilized. [0003] The published Chinese patent with publication number CN105271244A provides a method for synthesizing mesoporous m...

AI Technical Summary

Problems solved by technology

CN108675317A prolongs the single-pass life of SAPO-34 molecular sieve through post-treatment process, making the industrial cost of methanol synthesis olefin (MTO) reduced, but the silicon source used in its synthetic molecular sieve is organosilicon source, although it is more organic template agent triethylamine Easy to disperse in synthetic systems, but more expensive

Therefore, the cost of SAPO-34 synthesized from organosilicon sources is relatively high. Although it can be used as a catalyst for the synthesis of olefins from methanol, it limits its wide application in industrial wastewater treatment and other industrial fields with less economic added value.

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