The invention relates to a method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor. In a first aspect, the method makes use of an absorption step, wherein an anode outlet stream mass flow of the electrochemical cell reactor is exposed to an organic solvent being essentially immiscible with water for achieving an exergy-efficient separation of chlorine and hydrogen chloride. In a further aspect, the method makes use of absorption step, wherein the anode outlet stream mass flow is exposed to an ionic liquid, wherein the hydrogen chloride is dissolved in said ionic liquid, thereby forming a gas flow containing essentially chlorine and a solution mass flow comprising the ionic liquid and the hydrogen chloride. The hydrogen chloride is desorbed from the solution mass flow in a desorption step. In another aspect, the method makes use of a distillation step, wherein the anode outlet stream mass flow is separated at a static pressure of at least 2 bar for an exergy-efficient separation.

The invention relates to a method for separating chlorine from a gaseous anode outlet stream mass flow of an electrochemical cell reactor. In a first aspect, the method makes use of an absorption step, wherein an anode outlet stream mass flow of the electrochemical cell reactor is exposed to an organic solvent being essentially immiscible with water for achieving an exergy-efficient separation of chlorine and hydrogen chloride. In a further aspect, the method makes use of absorption step, wherein the anode outlet stream mass flow is exposed to an ionic liquid, wherein the hydrogen chloride is dissolved in said ionic liquid, thereby forming a gas flow containing essentially chlorine and a solution mass flow comprising the ionic liquid and the hydrogen chloride. The hydrogen chloride is desorbed from the solution mass flow in a desorption step. In another aspect, the method makes use of a distillation step, wherein the anode outlet stream mass flow is separated at a static pressure of at least 2 bar for an exergy-efficient separation.

A method for concentrating an aqueous hydrogen halide starting solution, in particular hydrochloric acid, includes the steps of extractive distillation of the aqueous hydrogen halide starting solution in the presence of an extraction agent in a distillation device, removing hydrogen halide vapor and/or hydrogen halide gas from the upper portion of the distillation device, removing an extraction-agent-containing solution from the lower portion of the distillation device, concentrating the extraction-agent-containing solution which is removed from the lower portion of the distillation device in an evaporation device, and returning the extraction-agent-containing solution which is concentrated in the evaporation device to the distillation device, wherein the extraction-agent-containing solution removed from the lower portion of the distillation device is concentrated in the evaporation device by evaporation at a pressure which is greater than atmospheric pressure.

The invention relates to a method of separating a phosgene- and hydrogen chloride-comprising stream (5), wherein said method comprises conveying the hydrogen chloride- and phosgene-comprising stream (5) into a distillation column (1), withdrawing at the bottom of the distillation column (1) a phosgene-comprising stream (7) and withdrawing at the top of the column an essentially hydrogen chloride-comprising stream (9). At least a portion of the stream (9) withdrawn at the top is compressed and at least partially condensed and at least a portion of the liquid and compressed essentially hydrogen chloride-comprising stream is decompressed and recycled into the top of distillation column (1) as reflux.

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 process of separating phosgene and hydrogen chloride, comprises: conveying a mixed stream containing hydrogen chloride and phosgene into a distillation column; withdrawing from the distillation column a bottom stream containing phosgene; withdrawing a top stream containing hydrogen chloride; compressing at least a portion of the top stream and at least partially condensing the compressed top stream to form a liquid stream, decompressing at least a portion of the liquid stream to form a cooled liquid stream and a cooled gas stream; and recycling the cooled liquid stream to the top of the distillation column as a reflux; the process additionally comprising temporarily introducing an absorbing solvent into the distillation column, in particular during starting-up and/or shutting-down of the process. The process allows for safe operation even when hydrogen chloride production only gradually begins or decreases, without the necessity of storing hydrogen chloride.

The invention relates to a method of separating a phosgene- and hydrogen chloride-comprising stream (5), wherein said method comprises conveying the hydrogen chloride- and phosgene-comprising stream (5) into a distillation column (1), withdrawing at the bottom of the distillation column (1) a phosgene-comprising stream (7) and withdrawing at the top of the column an essentially hydrogen chloride-comprising stream (9). At least a portion of the stream (9) withdrawn at the top is compressed and at least partially condensed and at least a portion of the liquid and compressed essentially hydrogen chloride-comprising stream is decompressed and recycled into the top of distillation column (1) as reflux.

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.