A rare earth-containing modified Y-type molecular sieve rich in secondary pores and its preparation method

Abstract

A rare earth-containing modified Y-type molecular sieve rich in secondary pores and a preparation method thereof. The Y-type molecular sieve has a rare earth content of 5 to 12% by weight, a sodium content of no more than 0.5% by weight, and a total pore volume of 0.36 to 0.48 mL. / g, the secondary pore volume accounts for 20~38% of the total pore volume, the unit cell constant is 2.440~2.455nm, the non-framework aluminum content accounts for less than 10% of the total aluminum content, the lattice collapse temperature is higher than 1060°C, B acid The ratio of the amount to the amount of L acid is not less than 3.50. The preparation method includes: preparing a Y-type molecular sieve with a conventional unit cell size containing rare earths, roasting it for 4.5 to 7 hours in an atmosphere of 350 to 520°C and 30 to 95 volume % water vapor, contacting with silicon tetrachloride gas and treating with acid. A step of. The modified Y-type molecular sieve has higher heavy oil conversion activity and lower coke selectivity, and has higher gasoline yield, liquefied gas yield, light oil yield and total liquid recovery.

Description

technical field [0001] The invention relates to a high-stability modified Y-type molecular sieve and a preparation method thereof, and further relates to a high-stability Y-type molecular sieve for heavy oil catalytic cracking and a preparation method thereof. Background technique [0002] Y-type molecular sieves have been the main active component of catalytic cracking (FCC) catalysts since they were first used in the 1960s. However, with the intensification of heavy crude oil, the content of polycyclic compounds in FCC raw materials increased significantly, but their diffusion capacity in zeolite channels decreased significantly. The pore size of Y-type molecular sieve as the main active component is only 0.74nm, and it is directly used to process heavy fractions such as residual oil. The accessibility of the active center of the catalyst will become the main obstacle to the cracking of polycyclic compounds contained therein. [0003] Molecular sieve pore structure is clo...

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Problems solved by technology

The ultra-stable molecular sieve prepared by this method has a high silicon-alumina ratio, a small unit cell constant, and contains a certain amount of rare earth, but it does not involve the preparation of a molecular sieve with secondary pores. The high-stable molecular sieve has poor accessibility to the active center , the activity is not high

[0014] The inventors of the present invention found that it is difficult for the ultra-stable Y-type molecular sieve prepared by the prior art to have high heavy oil catalytic cracking activity and good coke selectivity at the same time

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