A Y-type molecular sieve with ultra-high mesoporous content and preparation method thereof

Abstract

The invention provides a Y-type molecular sieve with an ultra-high mesoporous content and a preparation method of the Y-type molecular sieve. The method comprises the following steps: pre-treating Y-type zeolites for 1-5 hours at 300-600 DEG C; cooling to 200-600 DEG C; in an anhydrous drying environment, introducing dry gas saturated by a dealuminating silicon-reinforcing agent into the pre-treated Y-type zeolites and carrying out reaction for 0.5-7 hours to obtain a coarse product; or in the anhydrous dry environment, raising the temperature at a constant speed to 250-700 DEG C, introducing dry gas saturated by the dealuminating silicon-reinforcing agent into the pre-treated Y-type zeolites simultaneously and carrying out reaction for 0.5-7 hours to obtain a coarse product, wherein the introducing speed of the dry gas saturated by the dealuminating silicon-reinforcing agent is 50mL / minute; carrying out acid treatment on the coarse product; and carrying out alkaline treatment on the coarse product after acid treatment to obtain the Y-type molecular sieve. The invention further provides the Y-type molecular sieve with the ultra-high mesoporous content by virtue of the method. The sieve is the Y-type molecular sieve which is high in silica-alumina ratio, wide in range and high in mesoporous content; and the preparation method is simple to operate and low in raw material cost.

Description

Technical field [0001] The invention relates to a molecular sieve and a preparation method thereof, in particular to a Y-type molecular sieve with ultra-high mesopore content and a preparation method thereof, and belongs to the technical field of molecular sieve preparation. Background technique [0002] Because Y-type molecular sieve has suitable acidity, extremely high specific surface area and good thermal stability, it is widely used in catalytic cracking reactions. However, as a microporous molecular sieve, Y-type molecular sieve has disadvantages such as poor accessibility to acid sites and slow intracrystalline diffusion. [0003] In order to solve such problems, in the past 20 years, a large number of studies have aimed to form mesopores and macropores in microporous molecular sieves to form a hierarchical pore state and reduce the limitation of diffusion. The experimental methods include the hydrothermal synthesis of soft and hard template agents. Great progress has been ...

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Problems solved by technology

However, the article published by Krijn P.de Jong et al. in 2001 (Angew.Chem.Int.Ed.2001, 40, No.6) made an in-depth study of the Y-type prepared by hydrothermal dealumination by 3D-TEM technology. The mesoporous properties of molecular sieves found that the mesoporous structure mostly exists in the form of cavities inside the molecular sieve crystal, and the mesopores are only connected by micropores, lacking effective communication.

[0007] The alkali treatment method newly developed in recent years is also an effective means to create mesopores, but it has always been used in the desiliconization of high-silicon molecular sieves (such as ZSM-5, with an atomic silicon-aluminum ratio of not less than 15) to create mesoporous pores. There are not many applications of Y-type molecular sieves with aluminum ratio

[0008] Acid treatment dealumination to create mesoporous pores is mostly used in molecular sieves with low silicon-aluminum ratio. However, for Y-type molecular sieves, the synthetic NaY molecular sieve has a low silicon-aluminum ratio and high aluminum content in the framework. The acid treatment should consider the degree of dealumination, which is slightly different. Caution will cause the skeleton to completely collapse

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