A kind of preparation method of small grain nay molecular sieve

Abstract

The invention discloses a preparation method of a small-crystal-particle NaY molecular sieve. Hexamethylenetetramine is used as an additive, and the small-crystal-particle NaY molecular sieve is prepared in a segmental crystallization method. The method comprises the following steps: mixing a silicon source and an aluminum source, standing and aging for 2 to 72 hours at 5 to 60 DEG C to obtain a guide agent; then mixing the silicon source, the guide agent, the aluminum source and the hexamethylenetetramine to form cement, wherein in the reaction mixture gel, the molar ratio of Na2O, Al2O3, SiO2, H2O and C6H12N4 is (0.5-1):1:(5-40):(80-800):(0.5-10); static crystallizing in two segments under different temperatures, wherein the first-segment crystallization temperature is 60 to 85 DEG C, crystallizing for 12 to 48 hours, the second-segment crystallization temperature is 90 to 120 DEG C, and crystallizing for 12 to 72 hours; and finally filtering, washing and drying to obtain the small crystal-particle NaY molecular sieve. The relative crystallinity of the prepared composite molecular sieve is greater than 85 percent, and the size of a crystal size is 400nm to 600nm. The preparation method is easy for obtaining raw materials, low in preparation cost and good in industrial application prospect.

Description

technical field [0001] The invention belongs to the field of molecular sieve materials and preparation thereof, and in particular relates to a method for preparing small-grain NaY molecular sieves through segmental crystallization by using hexamethylenetetramine as a dispersant. technical background [0002] Y-type molecular sieve is the main active component of various petrochemical catalysts, and its pore structure, acidity and stability are important factors affecting catalytic performance and product distribution. In recent years, the oil refining industry has generally faced the problem of heavy feedstock oil, so it is particularly important to improve the accessibility of the active centers of oil refining catalysts and improve their ability to crack macromolecules. With the continuous development of new synthetic processes for molecular sieve materials, molecular sieves with small grains or nanoscale have become the focus of research and development of new petrochemic...

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Problems solved by technology

[0005] At present, the research on the preparation of small-grain NaY molecular sieves is limited to the two directions of feeding ratio and preparation process, and there is a lack of systematic research on the material phase and dispersion of the molecular sieve gelation process; at the same time, the preparation of dispersants added in the synthesis Complex process and high production cost lead to low synthesis efficiency and high production cost of small crystal molecular sieves

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