Modified Y-type molecular sieve and preparation method thereof

Abstract

The disclosure relates to a modified Y-type molecular sieve and a preparation method thereof. Based on the dry basis weight of the modified Y-type molecular sieve, the content of rare earth elements in the modified Y-type molecular sieve is 4-11% by weight in terms of oxides, and the content of P 2 o 5 The content of phosphorus is 0.05-10 wt%, the content of sodium oxide is 0.1-0.7 wt%, the content of active element oxide is 0.1-5 wt%, and the active element is gallium and / or boron; the modified Y-type molecular sieve The total pore volume is 0.33-0.39mL / g, and the pore volume of secondary pores with a pore diameter of 2-100nm accounts for 15-30% of the total pore volume; the unit cell constant of the modified Y-type molecular sieve is 2.440-2.455nm, The lattice collapse temperature is not lower than 1050°C; the non-skeletal aluminum content of the modified Y-type molecular sieve accounts for no more than 20% of the total aluminum content, and the ratio of the B acid content to the L acid content in the strong acid content of the modified Y-type molecular sieve Not less than 3.5. The molecular sieve has high crystallinity, thermal and hydrothermal stability, and has a secondary pore structure. When used for processing hydrogenated LCO, the LCO conversion efficiency is high, the coke selectivity is low, and the gasoline yield is higher and rich in aromatics.

Description

technical field [0001] The disclosure relates to a modified Y-type molecular sieve and a preparation method thereof. Background technique [0002] Light aromatics such as benzene, toluene and xylene (BTX) are important basic organic chemical raw materials, widely used in the production of polyester, chemical fiber, etc., and demand has been strong in recent years. Light aromatics such as benzene, toluene and xylene (BTX) mainly come from catalytic reforming and steam cracking processes using naphtha as raw material. Due to the shortage of naphtha raw materials, there is a large market gap for light aromatics. [0003] Catalytic cracking light cycle oil (LCO) is an important by-product of catalytic cracking, which is rich in aromatic hydrocarbons, especially polycyclic aromatic hydrocarbons, and belongs to the low-quality diesel fraction. With the development and change of market demand and environmental protection requirements, LCO is greatly restricted as a diesel blendin...

AI Technical Summary

Problems solved by technology

Rare earth-containing high-silicon Y-type zeolite can be prepared by performing multiple rare-earth ion exchanges and multiple high-temperature roasting on NaY zeolite. The disadvantages of zeolite are: because too harsh hydrothermal treatment conditions will destroy the structure of zeolite, Y-type zeolite with high silicon-alumina ratio cannot be obtained; although the production of aluminum outside the framework is very important for improving the stability of zeolite and forming new acid centers Beneficial, but too much aluminum outside the framework reduces the selectivity of zeolite; in addition, many dealuminated holes in zeolite cannot be filled by silicon migrated from the framework in time, often resulting in lattice defects of zeolite, and the crystallization of zeolite remains Therefore, the thermal and hydrothermal stability of the rare earth-containing high-silicon Y-type zeolite prepared by the hydrothermal method is relatively poor, which is manifested in the low lattice collapse temperature, the crystallinity retention rate and the ratio of crystallinity after hydrothermal aging. low surface area retention

The cracking activity of the catalyst made of the zeolite as the active component is not high, and the conversion rate of heavy oil is low

[0019] However, the existing ultra-stable Y-type molecular sieves containing phosphorus and rare earths have low heavy oil cracking activity and poor coke selectivity.

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