SAPO-34 molecular sieve aggregate, preparation method thereof and method for preparing olefin from methanol

Abstract

The invention relates to the field of SAPO-34 molecular sieves, and discloses an SAPO-34 molecular sieve aggregate, a preparation method thereof and a method for preparing olefin from methanol. The preparation method comprises the following steps of: (1) carrying out hydrothermal crystallization on a solution obtained by mixing an aluminum source, a phosphorus source, a silicon source, triethylamine, triethylamine hydrochloride and water; wherein in the solution, when Al2O3 is taken as the aluminum source, P2O5 as the phosphorus source, and SiO2 as the silicon source, the molar ratio of the aluminum source to the phosphorus source to the silicon source to triethylamine to triethylamine hydrochloride to water is 1: (0.9-1.1) : (0.1-0.5) : (1.5-3) : (0.1-0.5) : (15-50) ; (2) carrying out solid-liquid separation on the product obtained by hydrothermal crystallization in step (1), and washing, drying and roasting the obtained solid to obtain the SAPO-34 molecular sieve aggregate. The aggregate can be used as a catalyst in a reaction to prepare olefin by using methanol to improve the selectivity of the low-carbon olefin, inhibit the generation of carbon deposit and prolong the service life of the catalyst.

Description

technical field [0001] The invention relates to the field of SAPO-34 molecular sieves, in particular to a preparation method of SAPO-34 molecular sieve aggregates, the SAPO-34 molecular sieve aggregates prepared by the method and a method for producing methanol to olefins using the SAPO-34 molecular sieve aggregates. Background technique [0002] The silicoaluminophosphate (SAPO) series molecular sieves are new molecular sieves developed by Union Carbide Corporation (UCC) in 1984, and SAPO-34 is one of them. Its crystal structure is chabazite type (CHA), and the pore size is 0.43nm. It has special water absorption performance and proton acidity, and can be used as adsorbent, catalyst and catalyst carrier. Due to the unique small pore structure and suitable medium-strength acidity of SAPO-34, it exhibits high activity and selectivity in the reaction of methanol / dimethyl ether to low-carbon olefins (MTO), and the products are low-carbon olefins The selectivity is higher than ...

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Problems solved by technology

[0008] The purpose of the present invention is to provide SAPO-34 molecular sieve aggregates and a preparation method thereof and a method for methanol to olefins in order to overcome the low selectivity and easy generation of carbon deposits in conventional SAPO-34 molecular sieves for methanol-to-olefins products. -34 molecular sieve aggregates are micron cubes formed by closely stacking and stacking multiple nanosheet SAPO-34 molecular sieve grains, which can not only retain the advantages of nanocrystals in reducing internal diffusion, but also take advantage of the aggregated micron-scale structural scale The biggest advantages make molecular sieve products easy to separate and effectively reduce the production cost of molecular sieves

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