Method for synthesizing NU-88 molecular sieves

Abstract

The invention relates to a method for synthesizing NU-88 molecular sieves. The method comprises the following steps of (1) mixing 1,3-dibromopropane, 1-methyl-4-piperidone and a solvent, and carryingout a pre-reaction at 15-60 DEG C for 0.5-96 h to obtain a pre-reaction product, wherein a molar ratio of the 1,3-dibromopropane to the 1-methyl-4-piperidone to the solvent is 1 to (1.8 to 3) to (1 to20); and (2) mixing the pre-reaction product obtained in the step (1), an organic alkali, an inorganic alkali, an aluminium source, a silicon source and water to obtain a to-be-crystallized mixture,conducting hydrothermal crystallization treatment on the to-be-crystallized mixture, and recovering a solid product. According to the disclosed method, necessary tedious processes, including high-costseparation and purification, of conventional synthesis of a NU-88 molecular sieve template are omitted, large time consumption, energy consumption and material consumption are avoided, and the cost reduction effect is obvious.

Description

technical field [0001] The present disclosure relates to a method of synthesizing NU-88 molecular sieves. Background technique [0002] NU-88 molecular sieve is a new type of molecular sieve first disclosed by patent USP60277707. The method uses bis(N-methylpyrrolidine) alkylene bromide as a template, wherein the alkylene group has 4 to 6 carbons, and dynamic crystallization is required for 9 to 22 days at a reaction temperature of 160°C. Obtain NU-88 molecular sieve. The molecular sieve structure of NU-88 has not been fully analyzed. According to the existing characterization and reaction evaluation results, it is speculated that it may belong to the BET family and has a three-dimensional twelve-membered ring channel structure. [0003] Lee S B reported a method for synthesizing NU-88 molecular sieve in Journal of catalysis, 2003, 215: 151-170. The template used in this method is 1,6-bis(N-methylpyrrolidine) hexane bromide, and NU-88 molecular sieve can only be used in n...

AI Technical Summary

Problems solved by technology

[0005] At present, the method of synthesizing NU-88 molecular sieve is costly, which restricts its wide application

The high cost of the double quaternary ammonium salt template for the synthesis of NU-88 molecular sieve is one of the main reasons for the high cost of NU-88 molecular sieve

[0006] Synthetic double quaternary ammonium template agent 1, the method for 6-bis(N-methylpyrrolidine) hexane bromide (1,6-MPH) generally needs two kinds of raw materials 1-methylpyrrolidine (1-MP) and 1,6-dibromohexane (1,6-DBH) reacts in a certain proportion in an appropriate solvent, and crystallization and multiple recrystallization methods are required to obtain relatively pure 1,6-MPH. In the process of multiple recrystallizations, tedious operations such as freezing, filtering, washing with organic reagents, drying, adding appropriate organic solvents to dissolve, adding appropriate organic solvents to precipitate, filtering, washing, and drying, etc., consume a lot of time and Generate a lot of energy and material consumption

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