Method for increasing the silicon-aluminum ratio of y-type molecular sieve framework

Abstract

The present invention disclosed a method to improve the Silicon aluminum ratio of the Y -type molecular sieve. This method first sieve Y -type molecular sieve in the container, and then put the container into the inner lining of the reaction kettle equipped with organic carboxylic acid;The height of the carboxylic acid liquid level is lower than the height of the container; after the reactor is sealed, heated it, and the Y -type molecular sieve is treated under the pressure of the self -lifting pressure to generate the aluminum carboxylic acid aluminum / Y molecular sieve complex;If it is less than 0.2WT%, it is directly used as a solid acid catalytic material.When increasing the skeleton silicon aluminum ratio, the present invention can also release NA+ions with a balanced skeleton charged; on the one hand, the use of different switching agents can avoid roasting and reduce energy consumption; on the other handDuring the exchange process, unnecessary inorganic salt by -products were generated to reduce nitrogen -containing wastewater discharge.

Description

technical field [0001] The invention relates to the technical field of Y-type molecular preparation and improvement, in particular to a method for increasing the silicon-aluminum ratio of a Y-type molecular sieve skeleton. Background technique [0002] Y-type molecular sieve is a microporous silica-alumina material with crystal structure. Due to its large specific surface, excellent adsorption, ion exchange, and regular micropore channels, especially the large cavity (supercage, 1.3nm), it is widely used in industrial catalytic processes. Y-type molecular sieve is a kind of faujasite with FAU topology, and the basic unit in the molecular sieve framework is TO 4 structure, where T is a silicon or aluminum atom. The top angles are connected by T-O-T chemical bonds. Directly industrially synthesized Y-type molecular sieve framework silicon-aluminum ratio (SiO 2 / Al 2 o 3 ) at about 3-6, the high content of aluminum in the molecular sieve framework will reduce the acid str...

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Problems solved by technology

In addition, excessive inorganic ammonium salts are easily introduced during multiple ammonium exchanges, and the discharge of a large amount of nitrogen-containing wastewater will have adverse effects on the environment (US3402996, US4459271), and multiple roasting will increase energy consumption (CN1911513A); Organic and inorganic acids are used as proton sources to perform ion exchange on molecular sieves (CN102079531, CN102557070B), and because the molecular sieve framework has a low silicon-aluminum ratio and weak acid resistance, the molecular sieve framework collapses during the exchange process and the structure is incomplete (Catal.Rev .Sci.Eng.,17,1978,pp273-336)

However, when NH4Y or HY is hydrothermally treated, although the silicon-aluminum ratio of the molecular sieve framework can be increased, the molecular sieve framework structure is greatly damaged and the energy consumption is high; if SiCl4 or H2SiF6 / (NH4)2SiF6 sub>The method of dealuminating and supplementing silicon on molecular sieves has not been widely used because of the complicated operation process and difficult control of reaction conditions.

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