Preparation method of skeleton silicon-rich Y-shaped molecular sieve

Abstract

The invention discloses a preparation method of a skeleton silicon-rich Y-shaped molecular sieve, comprising the following steps of: firstly, carrying out desiliconizing pretreatment on a NaY molecular sieve with alkali lye and secondly carrying out ammonium exchange and dealumination and silicon reinsertion on the molecular sieve treated with alkali. The alkali treatment condition is to pulp and evenly mix the NaY molecular sieve and an alkali liquor in the mass ratio of NaY (dry basis): alkali: H2O being (0.1-2): (0.05-2): (4-15) and carry out alkali treatment at 0-120 DEG C for 0.1-24h. Compared with a product obtained by carrying out ammonium exchange and silicon-rich treatment on the NaY molecular sieve, the skeleton silicon-rich Y-shaped molecular sieve subject to the desiliconizing pretreatment has higher infrared acid quantity, B acid quantity and secondary pore content. A catalyst prepared from an active component which is the skeleton silicon-rich Y-shaped molecular sieve prepared by the method has stronger heavy oil transformation capability and higher light oil recovery rate when being used for a heavy oil cracking reaction.

Description

technical field [0001] The invention relates to a method for preparing a Y-type molecular sieve with a silicon-rich skeleton, and belongs to the technical field of molecular sieves. Background technique [0002] In the 1980s, the U.S. Union Carbon Company invented a method for preparing a skeleton silicon-rich Y-type molecular sieve (USP 4503023). In this method, the NaY molecular sieve was first subjected to ammonium ion exchange several times, and then the NH 4 A buffer solution such as ammonium oxalate is added to the NaY molecular sieve slurry to control the pH of the solution, and finally a certain concentration of ammonium fluorosilicate solution is slowly added, and the dealumination and silicon supplementation reaction is carried out at 70-90°C. During the reaction, the aluminum atoms in the molecular sieve framework structure are removed from the lattice under the action of ammonium fluorosilicate and dissolved into the solution, while the silicon source from ammoni...

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Problems solved by technology

However, this material also has serious shortcomings: in the process of modifying and preparing molecular sieve materials, in order to maintain the crystallinity of the product, people deliberately choose moderate dealumination and silicon supplementation conditions, so that dealumination and silicon supplementation on Y molecular sieve The speed is roughly the same, and the position where the dealumination of the framework occurs can be quickly filled by silicon atoms introduced from the outside, which not only improves the silicon-aluminum ratio of the framework, but also ensures that the framework is intact

Therefore, so far, there has been no relevant report on the direct use of strong alkali solution to treat NaY molecular sieves with low skeleton silicon-aluminum ratio.

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