Preparation method of high-purity arsenic trichloride

Abstract

The invention provides a preparation method of high-purity arsenic trichloride. The preparation method comprises the following steps: (1) mixing and stirring arsenic powder and sulfuric acid in a reactor; (2) introducing chlorine into the reactor, reacting until no solid exists, stopping introducing chlorine, and continuously stirring for 2-3 hours to obtain a crude arsenic trichloride solution and an arsenic-containing sulfuric acid solution; and (3) distilling the crude arsenic trichloride liquid, and collecting fractions at 130-140 DEG C to obtain high-purity arsenic trichloride. According to the preparation method, the sulfuric acid solution and the arsenic raw material are mixed in advance in the reactor, chlorine is introduced into the reactor to react with arsenic, the sulfuric acid solution covers the surface of arsenic, the reaction rate can be well controlled, and sulfuric acid can absorb generated impurities of arsenic trichloride, so that the impurity removal effect is achieved. Moreover, the method does not need to sublimate the arsenic powder and then react with chlorine, so that the energy consumption can be reduced, and the obtained arsenic trichloride is good in purity and high in yield.

Description

technical field [0001] The invention relates to the technical field of inorganic chemical industry, in particular to a preparation method of high-purity arsenic trichloride. Background technique [0002] Arsenic trichloride is an inorganic compound in the form of a colorless or light yellow fuming oily liquid. It is mainly used in the preparation of ceramics and the synthesis of arsenic and chlorine derivatives. High-purity arsenic trichloride is mainly used in epitaxy in the semiconductor manufacturing process. , diffusion process, and the preparation of high-purity arsenic. [0003] At present, the methods for producing arsenic trichloride mainly include hydrochloric acid method and gas phase chlorination method. The main steps of preparing arsenic trichloride by hydrochloric acid method are: adding diarsenic trioxide into the reactor, then adding concentrated hydrochloric acid, and slowly adding concentrated sulfuric acid dropwise under stirring. Due to the dropwise addi...

AI Technical Summary

Problems solved by technology

This method needs to sublimate the crude arsenic first, and the remaining residue in the sublimation furnace is easy to agglomerate, resulting in inconvenient operation

Moreover, when arsenic reacts with chlorine gas initially, the reaction is more violent, and it is difficult to control the reaction rate.

The absorption of arsenic-containing tail gas is usually sprayed with sodium hydroxide lye, and the arsenic-containing lye is directly treated as waste liquid. Many reagents are used in the treatment process, resulting in a large amount of arsenic-containing hazardous waste and high treatment costs.