Preparation method for concentrating pure silicon molecular sieve film with ethanol as fuel

Abstract

The invention provides a preparation method for concentrating a pure silicon molecular sieve film with ethanol as a fuel o and relates to a preparation method of a molecular sieve film. The preparation method comprises the following steps of: polishing and leveling a porous silicon dioxide ceramic tube carrier with sand paper, then washing in distilled water with ultrasonic waves, and weighing NaOH, tetrapropylammonium bromide (TPABr) and silica sol to prepare a synthetic solution; fixing the filled porous silicon dioxide ceramic tube with a polytetrafluoroethylene bracket, adding the synthetic solution, aging the synthetic solution in a baking box, crystallizing the synthetic solution at 180 DEG C, taking out, naturally cooling to room temperature, and washing to reach neutrality with the distilled water; and activating the dried molecular sieve film at the temperature of 400-600 DEG C so as to remove a template agent in a molecular sieve pore channel. According to the method, the performance of the synthesized silicalite-1 molecular sieve film and the preparation repeatability can be remarkably improved, the utilization rate of raw materials is enhanced; and the method is beneficial to reduction of the cost and is suitable for industrial magnification.

Description

technical field [0001] The invention relates to a preparation method of a molecular sieve membrane, in particular to a preparation method of a pure silicon molecular sieve membrane used for fuel ethanol concentration. Background technique [0002] Molecular sieve is a kind of aluminosilicate crystal material with regular pore structure, and its pore size is generally between 0.3 and 1.0 nm, which is similar to the size of ordinary molecules. The pore size of some molecular sieves (such as MFI molecular sieves) is similar to the molecular size of many important industrial raw materials, and the appropriate molecular sieve can be selected according to the different raw materials to be separated, and separated by molecular sieving or type-selective diffusion. Due to the single pore size distribution of molecular sieves and good thermal stability, chemical stability, mechanical stability and biological stability, it is widely used in catalysis, adsorption, gas separation, steam ...

AI Technical Summary

Problems solved by technology

[0004] According to the reports in the literature, there are two reasons why the high-performance, high-repeatability pure silicon silicalite-1 molecular sieve membrane is not easy to prepare: one is that the molecular sieve crystals are easy to deposit in the pores of the porous carrier and on the inner surface of the ceramic tube during the hydrothermal synthesis process. Formation, and thus reduce the separation performance of the membrane

Second, cracks are easily formed during the activation process of the pure silicon silicalite-1 molecular sieve membrane, resulting in a decrease in the separation performance of the membrane

In order to effectively reduce the adverse effects caused by the infiltration of synthetic liquid into the carrier, the organic polymer filling and TEOS and furfural mixture filling methods reported in the literature have certain limitations, the pretreatment method is relatively complicated, and is not suitable for tubular carriers. The use of tubular carriers is an inevitable choice to realize the industrialization of pure silicon molecular sieve membranes.

In addition, due to the difference in thermal expansion coefficient between the widely used alumina and stainless steel supports and the silicalite-1 molecular sieve, it is easy to cause cracks in the silicalite-1 molecular sieve membrane during the activation process, which eventually leads to a decline in the separation performance of the silicalite-1 molecular sieve membrane. In order to effectively improve the reproducibility and separation performance of pure silicon silicalite-1 molecular sieve membrane preparation, the selection of a suitable carrier and an effective activation method

At present, one of the main factors that prevents the large-scale preparation of pure silicon silicalite-1 molecular sieve membranes is the low repeatability of the preparation of the molecular sieve membranes, which leads to high membrane preparation costs and delays the industrialization process of the molecular sieve membranes.