Method for synthesizing MWW mole cular sieve

Abstract

The invention supplies a method to compound MWW molecular sieve. It adopts two-stage hydrothermal crystallization method that the room temperature at -119.9 degree centigrade is the first stage and 120-180 degree centigrade is the second stage. The alkali resource is one or two or three of hydroxide of Na, K and Ba. The silicon resource could be solid silica gel or liquid silica gel. And template agent could be HMI or the mixture of HMI and organic amine, quaternary ammonium salt, alcohols, and polyether. The invention has the advantages of compound method and condition is easy to control and low cost. The acid of the product could be altered by changing alkali resources.

Description

technical field [0001] The invention relates to a method for synthesizing molecular sieves, in particular to a method for synthesizing molecular sieves with MWW structure. Background technique [0002] Zeolite molecular sieve is an inorganic microporous material composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron as the basic structural unit. It has been widely used in the fields of catalysis, adsorption and ion exchange; as an excellent solid acid catalyst, it has been successfully It is used in more than 70 acid-catalyzed organic chemical processes. Since the pore size of the molecular sieve catalyst is equivalent to the size of the organic molecules participating in the reaction, it generally has a high selectivity, which is called the shape selectivity of the molecular sieve. When the kinetic radius of the reactant or product is larger than the pore size of the molecular sieve, it cannot pass through the pore size of the molecular sieve. Therefore, w...

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Problems solved by technology

[0008] At present, the aluminum sources used in the synthesis of MWW molecular sieves all use sodium aluminate, which is easy to introduce impurities in sodium aluminate into the synthesized molecular sieves. At the same time, the composition of sodium aluminate from different manufacturers or different batches varies greatly. It is difficult to control the composition of raw materials; the alkalinity adjustment of the synthesis system all uses sodium hydroxide, and the synthesized molecular sieves are all sodium-type molecular sieves. If molecular sieves containing other ions are to be obtained, they must be exchanged, which greatly increases the synthesis cost of molecular sieves. In addition, the synthesis of MWW molecular sieves all adopts hexamethyleneimine (HMI) or adds adamantane quaternary ammonium base therein as template, and these templates are expensive, resulting in higher production costs of MWW molecular sieves

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