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

Abstract

The invention provides a secondary-pore-rich modified Y type molecular sieve containing rare earth, and a preparation method thereof. In the modified Y type molecular sieve, the content of rare earthis 5 to 12 wt%; the content of sodium is no more than 0.5 wt%; a total pore volume is 0.36 to 0.48 mL / g; the pore volume of secondary pores accounts for 20 to 38% of the total pore volume; a lattice constant is 2.440 nm to 2.455 nm; the content of non-framework aluminum is no more than 10% of total aluminum content; lattice collapse temperature is higher than 1060 DEG C; and a ratio of the amountof acid B to the amount of acid L is no less than 3.50. A preparation method for the modified Y type molecular sieve comprises the following steps: preparing a rare earth-containing Y type molecular sieve with a conventional cell size; carrying out roasting in a water vapor atmosphere with a temperature of 350 to 520 DEG C and a volume percentage of 30 to 95% for 4.5 to 7 h; carrying out a contactreaction with silicon tetrachloride; and carrying out acid treatment. The modified Y type molecular sieve has higher heavy oil conversion activity, low coke selectivity, and higher diesel oil yield,light oil yield and total liquid yield.

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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