Nanometer needle-shaped SAPO-34 molecular sieve, as well as preparation and application thereof

Abstract

The invention relates to a nanometer needle-shaped SAPO-34 molecular sieve, as well as preparation and application thereof. A gel decondensation hydrothermal synthesis method is adopted and particularly comprises the following steps: (1) mixing an aluminum source, a phosphorus source, a silicon source, deionized water and a template agent, heating and stirring to obtain gel A; (2) adding excessive HF solution into the gel A, wherein the gel is decondensed into a solution at this moment; (3) performing hydrothermal crystallization: transferring the solution obtained in the step (2) into a polytetrafluoroethylene reaction kettle, performing high-temperature crystallization, rapidly cooling after the crystallization is completed, filtering and washing the obtained solid, drying and roasting to obtain the nanometer needle-shaped SAPO-34 molecular sieve. The preparation process is simple and easy to operate, and the molecular sieve has important application in methanol to olefin reaction; meanwhile, due to the special shape, the molecular sieve can serve as a carrier of catalyst active components and has potential industrial application prospect.

Description

technical field [0001] The invention belongs to the technical field of zeolite molecular sieve synthesis, and in particular relates to a method for synthesizing nano needle-like SAPO-34 molecular sieves. Background technique [0002] The silicoaluminophosphate molecular sieve SAPO-34 with CHA topology was designed and synthesized by Union Carbide Corporation in 1984. SAPO-34 molecular sieve belongs to the trigonal crystal system, R-3m space group, has an 8-membered ring channel structure, high specific surface area, suitable acidity and good hydrothermal stability, and has excellent performance in the catalytic reaction of methanol to olefins (MTO). It has excellent catalytic performance and high selectivity to low-carbon olefins, so it has attracted extensive attention from researchers. [0003] At present, there are many reports on SAPO-34 molecular sieves. Studies have shown that the preparation of SAPO-34 molecular sieves with smaller grain size can not only increase th...

AI Technical Summary

Problems solved by technology

The structure-directing agent introduced is a long-chain alkyltrimethylammonium halide. Since the structure-directing agent contains halogen and ammonia, it is easy to pollute the environment during sample processing.

[0005] Patent CN102616810A introduces a SAPO-34 molecular sieve with a crystal size of 20~300nm and a cubic or sheet shape. This patent uses a microwave-assisted synthesis method, but this synthesis method limits large-scale production and is difficult to apply in industrial production.

[0006] At present, the morphology of synthesized SAPO-34 molecular sieves is mostly cubic, and there are also reports of special shapes such as flakes, but there are no reports of nano needle-shaped SAPO-34 molecular sieves.

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