Hollow AFI type molecular sieve and preparation method thereof

Abstract

The invention discloses a hollow AFI type molecular sieve and a preparation method thereof. The molecular sieve is a hollow crystallization product which is prepared by mixing ionic liquid, an aluminum source, a phosphorus source, a fluorine source, water and a template agent, then performing reaction to prepare a molecular sieve synthetic gel, and then performing crystallization on the molecular sieve synthetic gel, wherein the mole ratio of the ionic liquid to the aluminum source (calculated in Al2O3) to the phosphorus source (calculated in P2O5) to the fluorine source (calculated in F) to the water to the template agent is (5-50):1:(1.8-4):(0-0.5):(0-10):(0.5-4). According to the hollow AFI type molecular sieve disclosed by the invention, the use amount of each raw material can be reasonably adjusted by introducing the ionic liquid into an aluminum phosphate molecular sieve synthetic system, the morphology of an aluminum phosphate molecular sieve is effectively changed, and an obvious hollow structure is synthesized; and the hollow AFI type molecular sieve is used as a catalyst carrier and is beneficial for diffusion of reactants and products, thereby significantly improving the conversion rate of catalytic reaction.

Description

technical field [0001] The invention belongs to the technical field of aluminum phosphate molecular sieves, in particular to a hollow AFI molecular sieve, and also to a preparation method of the hollow AFI molecular sieve. Background technique [0002] Molecular sieve refers to a class of substances with uniform micropores and whose pore size is equivalent to the size of ordinary molecules. Molecular sieves are widely used and can be used as high-efficiency desiccants, selective adsorbents, catalysts, ion exchangers, etc., but the cost of using chemical raw materials to synthesize molecular sieves is very high. Commonly used molecular sieves are crystalline silicates or aluminosilicates, which are connected by silicon-oxygen tetrahedrons or aluminum-oxygen tetrahedrons through oxygen bridges to form a molecular size (usually 0.3-2nm) channel and cavity system. Due to the different sizes and shapes of adsorbed molecules, it has the ability to screen fluid molecules of differ...

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Problems solved by technology

In 2013, Khoo et al. synthesized hexagonal flakes of AlPO by crystallizing for 90 hours in ionic liquid without template. 4 -5 molecular sieve, but the crystallization time is longer

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