A hydrogen gas recovery system according to the present ingestion is configured by a condensation and separation apparatus (A) that condenses and separates chlorosilanes from a hydrogen-containing reaction exhaust gas exhausted from a polycrystalline silicon production step, a compression apparatus (B) that compresses the hydrogen-containing reaction exhaust gas, an absorption apparatus (C) that absorbs and separates hydrogen chloride by contacting the hydrogen-containing reaction exhaust gas with an absorption liquid, a first adsorption apparatus (D) comprising an adsorption column filled with activated carbon for adsorbing and removing methane, hydrogen chloride, and part of the chlorosilanes each contained in the hydrogen-containing reaction exhaust gas, a second adsorption apparatus (E) comprising an adsorption column filled with synthetic zeolite that adsorbs and removes methane contained in the hydrogen-containing reaction exhaust gas, and a gas line (F) that recovers a purified hydrogen gas having a reduced concentration of methane.

Disclosed is a process for treating a gas stream containing hydrochloric acid, hydrofluoric acid, a fluorinated compound and halogenated organic compounds, wherein the gas stream is subjected to: (a) a step of washing with an acid solution to obtain a washed gas stream; (b) a step of adiabatic absorption in an aqueous solution of the hydrochloric acid contained in said washed gas stream, to collect a solution of hydrochloric acid; (c) a step of adsorption on activated carbon of the impurities present in said hydrochloric acid solution, to obtain a purified hydrochloric acid solution and a gas stream containing said fluorinated compound; and (d) a step of bringing said purified hydrochloric acid solution into contact with a silica gel. Also disclosed is a plant for the implementation of this process, and also a process for preparing a fluorinated compound comprising the catalytic pyrolysis of an organofluorine compound.

Disclosed is a process for treating a gas stream containing hydrochloric acid, hydrofluoric acid, a fluorinated compound and halogenated organic compounds, wherein the gas stream is subjected to: (a) a step of washing with an acid solution to obtain a washed gas stream; (b) a step of adiabatic absorption in an aqueous solution of the hydrochloric acid contained in said washed gas stream, to collect a solution of hydrochloric acid; (c) a step of adsorption on activated carbon of the impurities present in said hydrochloric acid solution, to obtain a purified hydrochloric acid solution and a gas stream containing said fluorinated compound; and (d) a step of bringing said purified hydrochloric acid solution into contact with a silica gel. Also disclosed is a plant for the implementation of this process, and also a process for preparing a fluorinated compound comprising the catalytic pyrolysis of an organofluorine compound.

Impure gaseous hydrogen chloride from organochlorosilane hydrolysis is freed of impurities by first scrubbing with an organochlorosilane, which may be the same or different from the organochlorosilane(s) hydrolyzed, and then further scrubbing with chloromethane. The purified gaseous hydrogen chloride is preferably used in chlorosilane synthesis.

A hydrogen gas recovery system according to the present ingestion is configured by a condensation and separation apparatus (A) that condenses and separates chlorosilanes from a hydrogen-containing reaction exhaust gas exhausted from a polycrystalline silicon production step, a compression apparatus (B) that compresses the hydrogen-containing reaction exhaust gas, an absorption apparatus (C) that absorbs and separates hydrogen chloride by contacting the hydrogen-containing reaction exhaust gas with an absorption liquid, a first adsorption apparatus (D) comprising an adsorption column filled with activated carbon for adsorbing and removing methane, hydrogen chloride, and part of the chlorosilanes each contained in the hydrogen-containing reaction exhaust gas, a second adsorption apparatus (E) comprising an adsorption column filled with synthetic zeolite that adsorbs and removes methane contained in the hydrogen-containing reaction exhaust gas, and a gas line (F) that recovers a purified hydrogen gas having a reduced concentration of methane.

Impure gaseous hydrogen chloride from organochlorosilane hydrolysis is freed of impurities by first scrubbing with an organochlorosilane, which may be the same or different from the organochlorosilane(s) hydrolyzed, and then further scrubbing with chloromethane. The purified gaseous hydrogen chloride is preferably used in chlorosilane synthesis.

The invention relates to a process for the treatment of a gas stream comprising hydrochloric acid, hydrofluoric acid and fluorinated/oxygenated compounds, in which the gas stream is successively subjected to: a stage of catalytic hydrolysis; a stage of washing with an acid solution; a stage of adsorption of impurities by active charcoal; a stage of adiabatic or isothermal absorption of the hydrochloric acid in an aqueous solution, making it possible to collect hydrochloric acid solution.

The invention relates to a process for the treatment of a gas stream comprising hydrochloric acid, hydrofluoric acid and fluorinated/oxygenated compounds, in which the gas stream is successively subjected to: a stage of catalytic hydrolysis; a stage of washing with an acid solution; a stage of adsorption of impurities by active charcoal; a stage of adiabatic or isothermal absorption of the hydrochloric acid in an aqueous solution, making it possible to collect hydrochloric acid solution.

The disclosure relates to a novel plant process for purifying hydrogen halide solutions. The process includes halogenating the organic compounds, particularly phenolic compounds, in the hydrogen halide solution to precipitate the halogenated compounds. The halogenated compounds can be filter, the hydrogen halide solution further purified on an adsorbent bed, and the clean hydrogen halide solution can be recycled or used in other processes.