Method for synthesizing Y type molecular sieve

Abstract

The invention discloses a method for synthesizing a Y type molecular sieve, and belongs to the technical field of preparation of catalysts. The method comprises the following steps of: mixing sodium metaaluminate and a silicon source in a reaction kettle, and performing rotary ageing to obtain a directing agent; adding the sodium metaaluminate and the directing agent into the silicon source in sequence, stirring, adding acidic aluminum salt, and continuously stirring to obtain silicon-aluminum gel; and crystallizing the silicon-aluminum gel in two steps, centrifuging, and drying to obtain the NaY type molecular sieve. The silicon-aluminum ratio of the synthesized NaY type molecular sieve is more than 5.0, and the average particle size of the sieve is not more than 100nm. The NaY type molecular sieve synthesized by the method is high in specific surface area, has higher performance in the aspects of converting macromolecules, reducing the secondary cracking of a product and the coking of a catalyst, and the like compared with the conventional Y type molecular sieve, is high in thermal stability and hydrothermal stability, is prepared from low-cost industrial raw materials, is environment-friendly, and has an industrial application prospect, and a framework of the sieve is high in silicon-aluminum ratio.

Description

technical field [0001] The invention belongs to the technical field of catalyst preparation, in particular to a method for synthesizing a Y-type molecular sieve. Background technique [0002] Y-type molecular sieves are widely used as catalysts or catalyst carriers in the petrochemical industry, especially in the field of catalytic cracking. With the heavy and inferior quality of catalytic cracking raw materials, the requirements for catalysts are becoming more and more stringent. The conventional Y-type molecular sieve has a small pore size, and it is difficult for heavy oil macromolecules to enter the pores. At the same time, it also limits the rapid diffusion of molecules, which is unfavorable for reducing secondary cracking and coking rate. Nano Y-type molecular sieve has a large proportion of surface atoms, a large number of catalytic active centers, and a high intracrystalline diffusion rate. It is superior to conventional Y-type molecular sieves in terms of convertin...

AI Technical Summary

Problems solved by technology

However, the quaternary ammonium base used in this method is commercially available chemicals, therefore, the cost of preparing molecular sieves by this method is relatively high, and it is difficult to realize industrial production

[0004] At present, many synthetic methods of small-grain NaY molecular sieves have been reported, and they can be summed up mainly as follows: the method introduced by USP3755538 is to add B, V, P in the guide agent , Mo, Ge and other metal elements, the crystal grain size of the synthetic NaY molecular sieve is 200-600nm, but the skeleton silicon aluminum of the product synthesized by this method is relatively low; in EP0435625A2, a Y-type molecular sieve smaller than 100nm was synthesized by the method of improving the system alkalinity, But the silicon-aluminum ratio of the molecular sieve synthesized by this method is also relatively low; the method introduced by CN10033593C is to add sodium silicate solution in the conventional directing agent with light transmittance75% improvement Directing agent solution, the crystal grain size of the synthesized NaY molecular sieve is 100-300nm, but this method is easy to cause pipeline blockage; USP3516786 adopts adding dispersion medium, such as methanol, ethanol, acetone, dimethyl sulfone, N, N-dimethyl Formamide, tetrahydrofuran, etc., the molecular sieves synthesized have a grain size of 10-100nm, but the production cost of this method is high, and it pollutes the environment

Images