Method for low-cost synthesis of ZSM-5 molecular sieve

Abstract

The invention belongs to the technical fields of molecular sieve and preparation method thereof, and specifically relates to a process for synthesis of a ZSM-5 molecular sieve by using a hydrothermal method and taking natural minerals diatomite and kaolin as raw materials for providing all aluminum sources and silicon sources required for synthesis of the ZSM-5, and particularly, relates to a method for low-cost synthesis of the ZSM-5-5 molecular sieve. The natural minerals diatomite and kaolin as the raw materials provide all the silicon sources and aluminum sources required for synthesis of the ZSM-5 molecular sieve, the use of any chemical silicon or aluminum products are not required, the ways of diatomite low temperature liquid alkali dissolving and kaolin low temperature solid alkali melting are provided for achieving low temperature high-efficiency activation of natural mineral silicon and aluminum 'nutrients', at the same time, inert impurities in the raw materials are removed, and crystallinity and purity of a crystallized product are improved. The method has obvious advantages in aspects of expanding the range of molecular sieve synthetic raw materials, increasing the added value of the natural mineral products, reducing the production cost of molecular sieve, reducing the environmental pollution and the like.

Description

technical field [0001] The invention belongs to the technical field of molecular sieves and preparation methods thereof, and specifically relates to a process for synthesizing ZSM-5 molecular sieves by using natural mineral diatomite and kaolin as raw materials to provide all the aluminum sources and silicon sources required for the synthesis of ZSM-5, and hydrothermally synthesizing ZSM-5 molecular sieves , specifically a low-cost method for synthesizing ZSM-5 molecular sieves. Background technique [0002] ZSM-5 zeolite molecular sieve is an inorganic crystalline material developed by Mobil Corporation. It is widely used as an FCC catalyst promoter because of its regular pore structure, strong acidity, good hydrothermal stability and excellent selectivity. , methanol to olefins catalysts and other fields. At present, the technology of synthesizing ZSM-5 zeolite molecular sieves with chemical products such as sodium silicate and sodium aluminate as raw materials is quite m...

AI Technical Summary

Problems solved by technology

[0004] Existing at present is the public report of synthesizing molecular sieve with natural mineral as raw material, and CN103043679A and CN103848439A openly reported respectively through the method for synthesizing Y-type molecular sieve and ZSM-5 molecular sieve with the natural mineral such as activated kaolin and diatomite through high-temperature roasting, although realize All the natural mineralization of the raw materials for the synthesis of silicon and aluminum by molecular sieves and the high value-added utilization of waste resources, but there are problems such as large energy consumption and low efficiency in the activation process of diatomite and kaolin

For the patent document of CN103848439A, after the natural mineral kaolin is mixed with sodium hydroxide solid, it still needs to be activated by high-temperature roasting at 600-1000°C, and diatomite is also thermally activated at 600-1000°C, which greatly increases the molecular sieve energy consumption of the synthesis process

In addition, the invention cannot avoid the use of organic templates in the synthesis process of ZSM-5 molecular sieves, which will not only cause great pollution to the environment, but also further increase the production cost of molecular sieves

[0005] CN101332995A and CN103387241A disclose a method for in-situ crystallization of natural mineral kaolin as raw material to synthesize ZSM-5 molecular sieve, but because the raw material of kaolin itself has a low silicon-aluminum ratio and cannot meet the requirements of ZSM-5 molecular sieve silicon-aluminum ratio, silicon has to be added Chemical products such as sodium bicarbonate or water glass are used as supplementary silicon sources

[0006] Through the above public reports, it is found that the raw materials for the synthesis of molecular sieves are mostly natural minerals such as kaolin and fly ash, and there are few research reports on the synthesis of ZSM-5 molecular sieves using diatomite as the main raw material.

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