Modification method for Y-type molecular sieve

Abstract

A modification method for a Y-type molecular sieve includes the steps of: a) adding water to NaY molecular sieve to pulp the molecular sieve, and adding polyhydroxy alcohol to the molecular sieve according to the alcohol-to-sieve ratio of 1-20:1, and treating the mixture at 80-200 DEG C to prepare slurry A; b) mixing the slurry A with organic alkali to prepare slurry B according to the alkali-to-sieve ratio of 0.1-1:1, and successively adding an aluminum source and a silicon source and aging the mixture to obtain slurry C, wherein the mass ratio of the aluminum source, on the basis of Al2O3, to the NaY molecular sieve is 0.1-1:1, the mass ratio of the silicon source, on the basis of SiO2, to the aluminum source, on the basis of Al2O3, is 0.1-0.5:1, and the silicon source is added after the aluminum source is fully and uniformly mixed with the slurry B; and c) performing hydrothermal crystallization to the slurry C in a sealed reaction kettle and collecting a product. The method can increase the silicon-aluminum ratio of framework of the molecular sieve and improve distribution of acidity, and meanwhile, ensures that the molecular sieve has better hydrothermal structural stability and excellent heavy oil conversion performance.

Description

technical field [0001] The invention relates to a method for modifying a Y-type molecular sieve. Background technique [0002] Since the Y-type molecular sieve was synthesized in the 1960s, it has been widely used in modern industry because of its uniform pore structure, excellent thermal and hydrothermal stability, strong acidity and high catalytic activity. As an important class of microporous catalytic materials, Y-type molecular sieves are also widely used in petroleum refining and processing, such as catalytic cracking, hydrocracking and other reaction processes, Y-type molecular sieves are the most important cracking active group in catalysts Yuan. [0003] The directly synthesized NaY molecular sieve has a high content of sodium oxide. Under high temperature hydrothermal conditions, Na ions will interact with the skeleton aluminum to destroy the molecular sieve structure. Therefore, the synthesized NaY molecular sieve cannot be directly used in refining processes suc...

AI Technical Summary

Problems solved by technology

Since Al-O bonds with longer bond lengths are replaced by Si-O bonds with shorter bond lengths, the unit cell of the molecular sieve decreases, and the silicon-aluminum ratio of the skeleton increases to a certain extent, but at the same time, the acid centers of the molecular sieve will be affected, and the acid content will decrease. , has a certain influence on cracking activity and selectivity

In addition, except for the hydrothermal method, other methods are mostly at the cost of loss of molecular sieve yield. Even with the addition of active silicon source, the overall molecular sieve yield is reduced, so it causes waste of aluminum source and may cause Pollution to the environment; while the hydrothermal method has no yield loss, the presence of non-framework aluminum and the loss of crystallinity are also unfavorable factors

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