A kind of preparation method of high crystallinity sapo-11 molecular sieve

Abstract

The invention discloses a method for preparing an SAPO-11 molecular sieve with high crystallinity. The method comprises the following steps: mixing nano lamelliform silicon-containing pseudo-boehmite with large specific surface area and large pore volume, phosphoric acid, an organic template agent and water so as to obtain a mixture, transferring the mixture into a polytetrafluoroethylene reaction kettle, implementing hydrothermal reaction, filtering, washing, drying and roasting, and obtaining the SAPO-11 molecular sieve with large specific surface area and high crystallinity. According to the method, the nano lamelliform silicon-containing pseudo-boehmite with the large specific surface area and the large pore volume is taken as an aluminum source, the lamella thickness is only 8, and relatively rich aluminum hydroxyl is accumulated on the surface, so that relatively rich active sites can be generated to promote generation of Al-O-P, and the reaction can be implemented under relatively gentle conditions; as silicon is introduced into the aluminum source to form framework silicon, the problem that the crystallinity of the molecular sieve is affected by amorphous phase of free silicon which is hard to enter framework can be solved.

Description

technical field [0001] The invention belongs to the technical field of molecular sieve synthesis, in particular to a method for synthesizing SAPO-11 molecular sieves. Background technique [0002] SAPO-11 molecular sieve is a mesoporous silicoaluminophosphate molecular sieve with AEL topological structure. It has one-dimensional straight channels and ten-membered ring elliptical channels. The channel size is 0.39nm×0.64nm. It belongs to the orthorhombic crystal system. The unit cell parameters A = 1.34nm, b = 1.87nm, c = 0.84nm, SAPO-11 molecular sieve is suitable for catalytic hydrocracking, isomerization, alkylation and light olefins due to its suitable pore structure and size and relatively mild acidity. It has broad application prospects in various oil refining and chemical industries such as polymerization. [0003] Since SAPO-11 is an aluminum-rich molecular sieve, the type of aluminum source has an important influence on the synthesis of the molecular sieve. The ear...

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Problems solved by technology

[0004] In the current literature reports, almost all industrially produced boehmite with large particles and high crystallinity is used as the aluminum source, and very few use nano-flaky boehmite as the aluminum source.

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