Method for recovering hydrogen from tail gas containing chlorsilane

Abstract

The invention discloses a method for recovering hydrogen from tail gas containing chlorsilane. The method comprises the following steps of: by a pressure-swing absorption method, performing pressure-swing absorption process for absorption and desorption on raw gas respectively through each absorption tower in a pressure-swing absorption system consisting of at least three absorption towers to obtain purified hydrogen, and performing circulatory operation in each absorption tower respectively according to the conventional pressure-swing absorption process. Absorption agents filled in the absorption towers comprise alumina, silica gel, active carbon and molecular sieves. The method can effectively separate and recover pure hydrogen from gases containing hydrogen, chlorine hydride, chlorsilane and the like, the recovery yield of hydrogen is high, the content of impurities of chlorine hydride, chlorsilane and the like remained in the product is low, the hydrogen purity is high, and simultaneously the components of chlorine hydride, chlorsilane and the like in the product can be separated and recovered. The equipment cost is low, the process is simple, and the energy consumption is low.

Description

technical field [0001] The invention belongs to the technical field of gas separation, in particular to a method for recovering hydrogen from tail gas containing chlorosilanes such as polysilicon or trichlorosilane. Background technique [0002] Under the background of vigorously developing new energy to replace traditional energy in today's society, the polysilicon and trichlorosilane industries are gradually recognized by the public and society, and quickly become a hot spot of attention. However, in the production process, process tail gas mainly containing hydrogen, hydrogen chloride, trichlorosilane and other components will be produced. Its tail gas composition is as shown in following table 1: [0003] Table 1 polysilicon, trichlorosilane tail gas components [0004] components H 2 HCl SiHCl 3 、SiCl 4 、SiH 2 Cl 2 N 2 Composition (V%) 79～96 3～17.84 1～2.97 0～0.19 [0005] Because it contains chlor...

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Problems solved by technology

[0011] The main purpose of the present invention is to address the above-mentioned deficiencies in the prior art, especially for the ordinary pressure swing adsorption method that cannot meet the requirements of removing impurities such as hydrogen chloride and chlorosilane, resulting in low product hydrogen purity, high impurity content, and low hydrogen recovery rate. low, but the use of temperature swing adsorption + rectification refrigeration separation has the disadvantages of high cost, complicated process, and high energy consumption. It provides a new method of pressure swing adsorption from polysilicon or trichlorosilane and other chlorosilanes. Method for separating and recovering hydrogen from tail gas

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