Low-silicon SAPO-34 molecular sieve as well as preparation method and application thereof

Abstract

The invention provides a low-silicon SAPO-34 molecular sieve as well as a preparation method and an application thereof. The preparation method of the low-silicon SAPO-34 molecular sieve comprises steps as follows: (1), guiding lyogel is prepared from a silicon source, an aluminum source, a phosphorus source, a seed crystal, a template agent and water through stirring and mixing at the temperature of 0-20 DEG C, and a seed crystal guiding liquid is prepared after the guiding lyogel is subjected to hydrothermal crystallization; (2), initial gel of the SAPO-34 molecular sieve is prepared from the silicon source, the aluminum source, the phosphorus source, the seed crystal guiding liquid, the template agent and water through stirring and mixing at the temperature of 0-20 DEG C; the initial gel of the SAPO-34 molecular sieve is subjected to low-temperature hydrothermal crystallization and high-temperature hydrothermal crystallization sequentially and then is subjected to aftertreatment, and the low-silicon SAPO-34 molecular sieve is prepared. According to the method, an inexpensive template agent can be used less or even cannot be used, and a product meeting requirements for crystallinity and purity is obtained without prolonging of crystallization time, and the preparation method of the low-silicon SAPO-34 molecular sieve is suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of oil refining, and in particular relates to a low-silicon SAPO-34 molecular sieve and its preparation method and application. Background technique [0002] SAPO-34 molecular sieve has a three-dimensional octanary pore structure of chabazite (CHA), the effective diameter of the pore is 0.43-0.50nm, suitable for medium-strength acidity, unique small pore structure, and has excellent catalytic performance in MTO, methanol The conversion rate is basically 100%, with good ethylene and propylene selectivity. Ethylene and propylene are important basic organic chemical raw materials in the chemical industry, and SAPO-34 molecular sieve has broad application prospects. [0003] Low-silicon SAPO-34 molecular sieve has high selectivity of low-carbon olefins in MTO catalytic reaction, especially the selectivity of ethylene, which is obviously better than ZSM-5, which promotes the industrialization of low-silicon SAPO...

AI Technical Summary

Problems solved by technology

For example CN102464338A discloses a kind of preparation method that adopts directing agent method to prepare small grain SAPO-34 molecular sieve, but this method is unsatisfactory in preparing low silicon SAPO-34 molecular sieve, and it must add when preparing crystallization directing agent Toxic and highly corrosive HF, so it is not suitable for large-scale industrial production

[0006] It can be seen that although some methods for preparing low-silicon SAPO-34 molecular sieves have been developed in the prior art, most of these methods have problems of poor economy and environmental pollution

Moreover, for low-silicon SAPO-34 molecular sieves, due to the influence of low silicon ratio, it is still difficult to obtain low-silicon SAPO-34 molecular sieve products with high crystallinity and small crystal grains

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