A kind of preparation method of lamellar sapo-34 molecular sieve

Abstract

The invention discloses a preparation method of a laminar SAPO-34 molecular sieve. The method comprises the following steps: gel a is obtained by uniformly mixing a phosphorus source, an aluminum source, a template agent, a silicon source and a solvent, and an accelerant solution is obtained by stirring and crystallizing the gel a; gel b is obtained by uniformly mixing the phosphorus source, the aluminum source, the silicon source, the template agent and water; the accelerant solution is added to the gel b, an obtained mixture is subjected to hydrothermal crystallization, centrifugal separation, washing, drying and roasting, and the laminar SAPO-34 molecular sieve is obtained. The SAPO-34 molecular sieve prepared with the method has laminar morphology and high degree of crystallinity, has shorter diffusion path on a section when applied to a reaction for preparing alkene from methanol, has excellent diffusion performance, and can prolong the service life of a catalyst and increase the yield of ethylene and propylene. The preparation method has the advantages that on one hand, the use amount of the template agent is reduced and the production cost is reduced accordingly, on the other hand, the crystallization time is shortened, and energy consumption is reduced.

Description

technical field [0001] The invention relates to a preparation method of SAPO molecular sieves, in particular to a preparation method of lamellar SAPO-34 molecular sieves. Background technique [0002] SAPO-34 molecular sieve has suitable acidity, small pore size and excellent hydrothermal stability, and exhibits excellent low-carbon olefin selectivity and methanol conversion rate in the reaction of methanol to olefins, so it is regarded as an excellent choice in the MTO process. The best catalyst, but the current SAPO-34 molecular sieve tends to produce serious carbon deposition and block the pores during the MTO reaction, resulting in catalyst deactivation. Studies have shown that the SAPO-34 molecular sieve with a particle size of less than 0.4 microns has the longest particle size in the MTO reaction. Long life and high diene selectivity, and almost no induction period, but the synthesis process of the current SAPO-34 molecular sieve with a particle size of less than 0.4 ...

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Problems solved by technology

[0002] SAPO-34 molecular sieve has suitable acidity, small pore size and excellent hydrothermal stability, and exhibits excellent low-carbon olefin selectivity and methanol conversion rate in the reaction of methanol to olefins, so it is regarded as an excellent choice in the MTO process. The best catalyst, but the current SAPO-34 molecular sieve tends to produce serious carbon deposition and block the pores during the MTO reaction, resulting in catalyst deactivation. Studies have shown that the SAPO-34 molecular sieve with a particle size of less than 0.4 microns has the longest particle size in the MTO reaction. Long life and high diene selectivity, and almost no induction period, but the synthesis process of the current SAPO-34 molecular sieve with a particle size of less than 0.4 microns is complicated, the cost is high, the separation is difficult, and the requirements for equipment are high, which is not conducive to Industrial production

[0003] The lamellar SAPO-34 molecular sieve has a short cross-sectional diffusion path, and the generated low-carbon hydrocarbons can quickly diffuse out to alleviate the formation of carbon deposits, so it has a longer catalytic life and higher diene selectivity; at the same time, other The two diffusion paths are long, have the characteristics of large crystal grains, are easy to separate, and are suitable for large-scale production, but the synthesis method of the lamellar SAPO-34 molecular sieve is expensive template agent, long production cycle, and easy to produce environmental pollution. Therefore, There is an urgent need to develop a simple, efficient, economical, and suitable for industrial production of lamellar SAPO-34 molecular sieves

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