A kind of highly stable modified Y-type molecular sieve with high yield isomerism C4 and preparation method thereof

Abstract

The invention discloses a high-stability modified Y-type molecular sieve for high production of isomerized C4 and a preparation method of the high-stability modified Y-type molecular sieve. The CaO content of the modified Y-type molecular sieve is 0.3-4 wt%, the RE2O3 content is 2 to 7 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 the secondary pores of 2-100nm accounts for 10-25% of the total pore volume; the lattice constant is 2.440-2.455 nm, the content of non-framework aluminum accounts for not more than 20% of the total aluminum content, the lattice collapse temperature is not lower than 1050 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 preparation method 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 isomeric C4 yield, and higher isomeric hydrocarbon content in gasoline.

Description

technical field [0001] The invention relates to a highly stable modified Y-type molecular sieve capable of producing more isomeric C4 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. In this method, 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. Silica Y-type zeolite is the most conventional method, 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 generation of extra-framework aluminum is beneficial to improving the stability of zeolite and forming new acid centers, too much extra-framework alum...

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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. In this method, 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. Silica Y-type zeolite is the most conventional method, 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 generation of extra-framework aluminum is beneficial to improving the stability of zeolite and forming new acid centers, too much extra-framework aluminum reduces the selectivity of zeolite. Migrated silicon fills up, often causing 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, and usually can only increase the content of isobutane, but cannot effectively increase the content of isomeric hydrocarbons in gasoline

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