Synthetic method of MgSAPO-31 molecular sieve

Abstract

The invention discloses a synthetic method of a MgSAPO-31 molecular sieve, relating to a synthetic method of a molecular sieve, and aiming to solve the problems that only a molecular sieve with an acid site can be synthesized at present by adopting the conventional silicon source and aluminum source and mixed crystals are easily formed in a crystallized product. The synthetic method comprises the steps of 1, dispersing a NaX molecular sieve into a magnesium nitrate solution or magnesium acetate solution to perform ion exchange, and controlling the exchange frequency and exchange time to obtain a Mg / NaX molecular sieve; 2, mixing phosphoric acid, pseudo-boehmite, the Mg / NaX molecular sieve, di-n-butylamine and deionized water, and stirring to obtain an initial gel; 3, putting the initial gel into a crystallization kettle, performing crystallization at 170-190 DEG C, performing centrifugal separation, washing and drying on a crystallization product, and then roasting to obtain a molecular sieve. According to the synthetic method disclosed by the invention, a molecular sieve framework contains two acid sites of Si and Mg with different strengths at the same time, the preparation purity is high, and the molecular sieve can be used as a catalyst applied to the fields of petrochemical industry and the like.

Description

technical field

[0001] The invention relates to a synthesis method of molecular sieves, in particular to a method for simultaneously replacing aluminum phosphate molecular sieves AlPO with Mg and Si 4 The preparation method of the MgSAPO-31 molecular sieve of -31. Background technique

[0002] In 1984, Lok et al. successfully introduced Si into AlPO 4 Among the series of molecular sieves, a series of silicoaluminophosphate molecular sieves (SAPO-n) with negatively charged skeletons, exchangeable cations and proton acidity were synthesized. Among them, the mesoporous SAPO-31 molecular sieve has suitable pore size and temperature acidity, As a catalyst for alkylation, amination and isomerization reactions, it has broad application prospects in petroleum refining, petrochemical and other fields. U.S. Patent USP4,1984,440:871 and the synthesis of the SAPO-31 molecular sieve of follow-up work report usually adopt dipropylamine to make template agent, take aluminum isopropoxide ...

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