Method for synthesizing molecular sieve membrane by dip coating-rubbing crystal-coating method

Abstract

The invention discloses a method for synthesizing a molecular sieve membrane by a dip coating-rubbing crystal-coating method. The method comprises the following steps: (1) introducing a layer of molecular sieve crystal seeds onto a carrier by using a dip coating method, and rubbing the carrier coated with the crystal seeds on soft cloth to obtain a crystal seed coated carrier; (2) preparing molecular sieve membrane reaction solution; and (3) synthesizing the molecular sieve membrane by adopting a hydrothermal synthesis method, namely placing the crystal seed coated carrier into synthetic solution, taking out a membrane tube after the molecular sieve membrane is synthesized, and washing and drying the molecular sieve membrane, wherein in the (1), the dipping and drawing speed of a drawing machine is 0.1 to 5 centimeters per second, the dip coating time is 1 to 50 seconds, the concentration of dip coating solution is 5 to 50 grams per liter, and the size of the crystals is 0.20 to 10 meters; in the (2), the motor ratio of components Na2O, Al2O3, SiO2 to H2O is 1-20: 1: 1-200: 50-5,000; and in (3) the crystallization temperature is between 60 and 200 DEG C, and the crystallization time is 1 to 100 hours. The synthesized molecular sieve membrane has good separating property, and the method is simple and has good repeatability.

Description

technical field [0001] The invention relates to a method for synthesizing molecular sieve membranes, in particular to a method for synthesizing molecular sieve membranes by a dip coating-rolling wiping crystal method. 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: 1) Molecular sieves have regular and orderly channels 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 obtained by molecular sieving or shape-selective diffusion. separate. 2) Molecular sieves have good chemical stability and thermal stability. 3) The diversity of molecular sieve structures leads to the diversity of its properties, such as different pore sizes and different hyd...

AI Technical Summary

Problems solved by technology

The dipping crystal coating method is the most commonly used crystal coating method at present, but in the process of dipping crystal coating, the molecular sieve seed liquid is difficult to be closely combined with the carrier surface and is easy to flow, so it is difficult to form a uniform and continuous seed layer

The wiping and coating crystal method is the easiest to operate, but it is actually difficult to introduce a uniform and continuous layer of seed crystals on the surface of the carrier.

Although the spray coating method can introduce a uniform and continuous seed crystal film on the surface of the flat carrier, it is difficult to form a uniform and continuous seed crystal layer on the surface of the tubular or hollow fiber carrier, so it is not suitable for industrial scale-up and has no industrial application. value

Although the laser pulse deposition coating method can introduce a uniform and continuous seed crystal film on the surface of the carrier, it requires expensive lasers, so it has no industrial application value

However, by adjusting the Zeta potential of the alumina carrier and the seed crystal or introducing the seed layer on the surface of the carrier through electrostatic interaction, the operation is complicated, difficult to control, and not suitable for industrial scale-up.

These reasons restrict the synthesis of molecular sieve membranes to a certain extent, thus also restricting the industrial application of molecular sieve membranes.

Images