A kind of highly stable modified Y-type molecular sieve producing more isomeric hydrocarbons and its preparation method

Abstract

The invention relates to a high-stability modified Y-type molecular sieve for high production of isohydrocarbons and a preparation method thereof. The MgO content of the modified Y-type molecular sieve is 0.5-4.5 wt%; the content of Na2O is 0.1 to 0.5 wt%; the total pore volume is 0.33 mL / g to 0.39 mL / g; the pore volume of secondary pores of 2-100nm accounts for 10-25% of the total pore volume; the lattice constant is 2.440-2.455 nm, the non-framework aluminum content accounts for not higher than 20% of the total aluminum content, the lattice collapse temperature is not lower than 1040 DEG C,and the ratio of the amount of acid B to the amount of acid L measured by a pyridine adsorption infrared method at 200 DEG C is not lower than 2.30; the molecular sieve has no absorption peak at the wavelength of 285-295 nm in an ultraviolet-visible absorption spectrum. The preparation method of the molecular sieve comprises the steps of ion exchange, modification treatment under certain temperature and water vapor conditions and reaction with silicon tetrachloride. The modified Y-type molecular sieve has higher heavy oil conversion activity, lower coke selectivity, higher gasoline yield and liquefied gas yield, and higher isohydrocarbon content in gasoline.

Description

technical field [0001] The invention relates to a high-stability modified Y-type molecular sieve capable of producing more isomeric hydrocarbons and a preparation method thereof. Background technique [0002] At present, the industrial production of high-silicon Y-type zeolite mainly adopts the hydrothermal method, and the NaY zeolite is subjected to multiple rare earth ion exchange and high-temperature roasting, and high-silicon Y-type zeolite containing rare earths can be prepared, which is also the preparation of high-silicon Y-type zeolite. The most conventional method for Y-type zeolite, but the disadvantage of preparing rare earth high-silicon Y-type zeolite by hydrothermal method is that the structure of zeolite will be destroyed due to too harsh hydrothermal treatment conditions, and Y-type zeolite with high silicon-aluminum ratio cannot be obtained; Although the production of external aluminum is beneficial to improve the stability of zeolite and form new acid cente...

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Problems solved by technology

[0002] At present, the industrial production of high-silicon Y-type zeolite mainly adopts the hydrothermal method, and the NaY zeolite is subjected to multiple rare earth ion exchange and high-temperature roasting, and high-silicon Y-type zeolite containing rare earths can be prepared, which is also the preparation of high-silicon Y-type zeolite. The most conventional method for Y-type zeolite, but the disadvantage of preparing rare earth high-silicon Y-type zeolite by hydrothermal method is that the structure of zeolite will be destroyed due to too harsh hydrothermal treatment conditions, and Y-type zeolite with high silicon-aluminum ratio cannot be obtained; Although the production of external aluminum is beneficial to improve the stability of zeolite and form new acid centers, too much aluminum outside the framework reduces the selectivity of zeolite. In addition, many dealuminated holes in zeolite cannot be migrated out of the framework in time. The addition of silicon often causes lattice defects of zeolite, and the crystallization retention of zeolite is low

However, the Y molecular sieve prepared by this method has poor thermal and hydrothermal stability, unsatisfactory reactivity and selectivity, and can only increase the content of isobutane, but cannot effectively increase the content of isomeric hydrocarbons in gasoline.

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