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.

A purified hydrochloric acid composition is prepared from a stream of a contaminated hydrochloric acid composition by a process comprising a distillation treatment, wherein at least a first distillation column is operated at a first pressure and a second distillation column is operated at a second pressure, which second pressure is lower than the first pressure; wherein the contaminated hydrochloric acid composition comprises water, contaminants and hydrochloric acid in a first hydrochloric acid concentration of above the azeotropic composition of hydrochloric acid and water at the first pressure; wherein a part of the stream of the contaminated hydrochloric acid composition is fed into the first distillation column to yield a first bottom product comprising water and hydrochloric acid with a hydrochloric acid concentration below the first hydrochloric acid concentration and a first top product comprising hydrochloric acid in a concentration above the azeotropic hydrochloric acid composition at the first pressure; wherein at least a portion of the first bottom product is passed to the second distillation column; wherein another part of the stream of the contaminated hydrochloric acid composition is fed into the second distillation column to yield a second top product comprising contaminants and water, and a second bottom product comprising water and hydrochloric acid; wherein at least a part of the second bottom product is recycled into the first distillation column; and wherein the first top product is recovered as purified hydrochloric acid composition.

A process of producing chlorine gas by catalytic oxidation of hydrogen chloride including: incorporating an oxidizing agent such as ozone, hydrogen peroxide solution etc. into a gas stream of hydrogen chloride containing impurities, conducting oxidation pretreatment of the gas stream under the action of ultrasonic wave, such that the impurities contained in the gas stream are oxidized; where the gas stream obtained after the oxidation pretreatment is allowed to pass through a separating device, the oxidized impurities in the form of liquid and/or the oxidized impurities in the form of solid are removed from the gas stream so as to obtain a purified gas stream of hydrogen chloride, and thereafter the purified gas stream of hydrogen chloride is well mixed with a gas stream containing molecular oxygen, the resultant gas mixture is preheated to a reaction temperature, and then catalytically oxidized to produce chlorine gas.

The present invention relates to a method and a system for separating and treating impurities from a hydrogen chloride liquid mixture, and particularly relates to a method and a system for separating and treating impurities from a hydrogen chloride liquid mixture produced from the process for preparing isocyanate with phosgenation. Said method comprising the steps of: sending said hydrogen chloride liquid mixture into a gas-liquid separation column for separation to yield a liquid phase flow comprising impurities at the bottom of said gas-liquid separation column, and the impurities comprising ammonium chloride; making the liquid phase flow comprising impurities flow into a neutralization tank through a liquid phase flow pipeline from the bottom of the gas-liquid separation column, neutralizing the liquid phase flow comprising impurities with an alkaline liquid in the neutralization tank to yield a neutralized solution, and sending the neutralized solution into a waste liquid treatment device from said neutralization tank for treatment. The method and system provided by the invent ion solve the problem of the blocking of the liquid flow pipeline, the valve and the gas-liquid separation column due to impurity deposit ion, and reduce the shutdown frequency for maintenance.

A method for processing hydrogen chloride from isocyanate preparation comprises the steps: a) providing hydrogen chloride; b) purifying the hydrogen chloride provided; and furthermore step c) or step d): c) bringing the purified hydrogen chloride into contact with water and/or with hydrochloric acid which is not saturated with respect to uptake of hydrogen chloride, d) further processing the purified hydrogen chloride to chlorine by partial oxidation. The hydrogen chloride provided in step a) contains organic and/or nitrogen-containing impurities and in step b) the purification is carried out by bringing hydrogen chloride into contact with hydrochloric acid which is saturated to the extent of 90% with respect to uptake of hydrogen chloride at least in a first gas scrubber (10) and circulating this hydrochloric acid at least partially through the first gas scrubber (10).

The present invention relates to a continuous process for preparing chlorine and a production unit for carrying out said process. The present invention further relates to a use of said production unit for the continuous production of chlorine.

A process has been disclosed for preparation of hydrobromic acid from bromine, sulfur dioxide and water, which involves in situ generation of bromine from bittern for the production of hydrobromic acid and separation thereof from co-products, viz., sulfuric and hydrochloric acids. The invented process obviates the need for double distillation or precipitation step for removal of sulfate impurities. The concentration of the product obtained by the disclosed process is about 48% and it contains <15 ppm sulfate and chloride impurities.

A process for removing halogen compounds, particularly chlorine compounds, from a process fluid, includes the steps of (i) passing a process fluid containing hydrogen halide over a first sorbent to remove hydrogen halide and generate a hydrogen halide depleted process fluid and then, (ii) passing the hydrogen halide depleted process fluid over a second different sorbent to remove organic halide compounds therefrom. A purification system suitable for removing hydrogen halide and organic halide compounds from process fluids is also described.

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.

Solid saccharides are produced from an aqueous saccharide solution in a process, where the aqueous saccharide solution is admixed with a carrier liquid in which the saccharides are insoluble and that has a boiling point higher than that of water to obtain an aqueous admixture, and where the aqueous admixture is subjected to an evaporation step. The heat for the evaporation is at least partially supplied by a heated surface area to yield a vapor fraction including water and a residue fraction including solid saccharides and carrier liquid.