Method of exhausting and in-situ hydrothermally synthesizing type-A molecular sieve film

Abstract

The method of exhausting and in-situ hydrothermally synthesizing type-A molecular sieve film includes: pumping with water pump or compressing with compressor to make the crystal kernel formed in the synthetic liquid migrate fast to the surface of the base film to speed the synthesis of type-A molecular sieve film, with the pumping or compressing pressure being 0.0005-0.0500 MPa and the pumping or compressing time being 10-500 min; and hydrothermally synthesizing type-A molecular sieve film in the solution comprising Na2O in 20-100 portions, Al2O3 in 0.5-5 portions, SiO2 in 5 portions and H2O in 500-4000 portions at 323-373 K for 1-60 hr. The present invention has obviously reduced molecular sieve film synthesizing time and raised material utilization, and the synthesized molecular sieve film is homogeneous, compact and continuous.

Description

technical field [0001] The invention relates to a method for synthesizing molecular sieve membranes, and in particular provides a method for quickly synthesizing high-performance molecular sieve membranes by means of water pump evacuation or compressor compression. Background technique [0002] Molecular sieve is a microporous inorganic crystal material formed with silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron as the basic skeleton. Molecular sieves have the following advantages as inorganic membrane materials: [0003] 1) Molecular sieves have well-regulated pores with a single pore size distribution; and the pore size of molecular sieves is similar to the molecular size of many important industrial raw materials, and molecules can be separated by molecular sieving or type-selective diffusion. [0004] 2) Molecular sieves have good chemical stability and thermal stability. [0005] 3) The diversity of molecular sieve structures leads to the diversity of its p...

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Problems solved by technology

In this way, on the one hand, in a relatively short period of time, the surface of the basement membrane cannot form a dense and continuous molecular sieve film due to the lack of sufficient molecular sieve grains, but prolonging the time of hydrothermal synthesis will inevitably lead to the occurrence of crystal transformation; on the other hand Most of the molecular sieve grains are deposited to the bottom of the reactor due to gravity, causing great waste (research shows that the utilization rate of molecular sieve grains is only 20-30%), especially as the synthesis time increases, the crystal nucleus or molecular sieve The longer the grain grows, the greater the negative effect of gravity

In addition, gravity makes the crystal nuclei or molecular sieve crystals migrate and adsorb to the surface of the basement membrane in different directions, and the thickness of the molecular sieve membrane formed at the upper and lower ends is very different. Therefore, it is difficult to form a uniform and continuous molecular sieve membrane on the surface of the basement membrane.

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