Molecular sieve film and preparation method thereof

Abstract

The invention relates to a molecular sieve film and a preparation method thereof, in particular to an aligned nano laminar AFI or CHA type molecular sieve film and an in-situ preparation method thereof based on layer-by-layer film coating and vapor-phase transfer. The molecular sieve film is composed of nano laminar AFI or CHA type molecular sieve crystals in aligned arrangement. The method comprises the following steps: successively coating two film-coating liquids on a glass sheet support, and then carrying out in-situ crystallization by vapor-phase transfer. The layer-by-layer film-coating preparation method does not need the introduction of crystal seeds or the aging of a synthesis liquid, has the advantages of convenient operation and high film-forming repeatability and can realize the industrial expanded production easily. By simultaneously combining vapor-phase transfer to carry out crystallization, the invention greatly reduces the preparation cost of the molecular sieve film and is beneficial to the cyclic utilization of the template agent.

Description

technical field [0001] The invention relates to a molecular sieve membrane and a preparation method thereof, in particular to an oriented nanosheet AFI or CHA type molecular sieve membrane and its in-situ preparation method of a layer-by-layer coating film gas phase transfer method. Background technique [0002] Molecular sieve is a kind of aluminosilicate crystal with rich and uniform microporous structure. Its particle size can be adjusted from nanometer to micrometer. It has large specific surface area, high hydrothermal stability, and unique surface and ion exchange properties. It has been widely used in Catalysis, adsorption, separation and other fields. Molecular sieves are prepared as a continuous film layer with fewer defects formed by the intergrowth of molecular sieve crystals, that is, molecular sieve membranes. Molecular sieve membranes can be divided into three categories: filled membranes (embedded membranes), self-supporting membranes, and supported membranes....

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Problems solved by technology

At the same time, each preparation method also has shortcomings: due to the lack of understanding of the nucleation phenomenon and growth of molecular sieves in hydrothermal systems, especially the lack of understanding of the control of particle shape and crystal nucleation density on any carrier, the use of in situ synthesis The oriented molecular sieve membrane obtained by the method is limited to several kinds of molecular sieves; however, it is inevitable to prepare nano-scale molecular sieve crystals in advance as seed crystals in the secondary growth method, and the coating process is heavy and the cost is increased; the microwave synthesis method involved The equipment is expensive and it is not easy to scale up continuous production; although the gas phase transfer method is more environmentally friendly and easy to continue production, it is a derivative technology based on the first two methods after all, which cannot avoid the long-term aging of the synthetic solution, the process of seed crystal preparation and the Difficulties such as very uniform coating liquid requirements

[0005] From the above preparation methods of molecular sieve membranes and the successful cases of directional synthesis of molecular sieve membranes, it can be seen that no matter from the perspective of the operability of the preparation method or the sustainability of the preparation technology, it is necessary to quickly, easily and environmentally friendly prepare nano-scale Crystal oriented molecular sieve membranes are still very difficult, and the report of preparing nanoscale oriented molecular sieve membranes by gas phase transfer method has not been seen so far.

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