The invention relates to an improved process for making available the coproduct hydrogen chloride obtained in the preparation of an isocyanate by phosgenation of the corresponding amine for a desired subsequent use (i.e. a chemical reaction), in which part of the total hydrogen chloride obtained is isolated in gaseous form at a pressure which is higher than the pressure desired for the subsequent use of the hydrogen chloride by lowering the pressure of the crude product from the phosgenation and the remaining part of the total hydrogen chloride obtained is separated off at a pressure lower than that desired for the subsequent use from the liquid crude product from the phosgenation remaining after lowering of the pressure and is subsequently compressed to a pressure which is higher than that desired for the subsequent use, and in which the two hydrogen chloride streams obtained in this way are, preferably together after having been combined, purified so as to give a purified hydrogen chloride at a pressure which is higher than the pressure desired for the subsequent use.

A method for separating a mixture of materials A and B by extractive distillation, using an extraction medium having a higher affinity to B than to A, collecting a liquid fraction on a collecting tray and heated and partially evaporated in a first indirect heat exchanger, collecting the resultant vapor is released into the column and a non-evaporated proportion of the liquid fraction in the sump of the column, and a series of heating, separation and cooling where partially cooled extraction medium fraction is used as heating medium for a heat exchanger.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler. Some embodiments of a biogas cleaning method can also include precooling the biogas waste stream, adsorbing siloxanes from the biogas waste stream and adsorbing hydrogen chloride from the biogas stream.

A process is provided for producing potassium sulfate from potassium chloride and sulfuric acid. The process entails mixing potassium chloride with the water to form a potassium chloride slurry which is mixed with recycled sulfuric acid to form a K.sup.+, Ct, SO.sub.4.sup.2 acid mixture. This mixture is subjected to a crystallization process that produces potassium sulfate crystals and a hydrochloric acid-water vapor. The hydrochloric acid is separated from the hydrochloric acid-water vapor to form a hydrochloric acid solution.

The invention pertains to a method for recovering HCl from a HCl containing gas stream wherein a HCl containing gas stream with a temperature of 20 to 25 C. is provided to an adiabatic absorption unit where it is contacted with water as an absorbent, resulting in the formation of a top gas stream and a aqueous HCl product solution, wherein the temperature of the top gas stream is at least 70 C. and wherein the aqueous HCl product solution has a HCl concentration in the range of 5-20 wt. %. It is preferred for the HCl-containing gas stream to be derived from a hydrogenation step wherein a feed comprising monochloroacetic acid (MCA) and dichloroacetic acid (DCA) is reacted with hydrogen to form a HCl-containing gas stream and a product stream comprising MCA and a reduced amount of DCA. The HCl product solution is preferably diluted to a concentration of 1-8 wt. %, and the diluted solution is used as absorbent in a second absorption step, wherein HCl is absorbed from a further HCl-containing gas stream to form a second aqueous HCl solution. The further HCl-containing gas stream is preferably derived from a chlorination step wherein acetic acid is reacted with chlorine, resulting in the formation of the further HCl-containing gas stream and a feed comprising monochloroacetic acid (MCA) and dichloroacetic acid (DCA).

The present invention relates to a method of purifying waste hydrochloric acid, and more particularly, to a method of purifying waste hydrochloric acid which includes preparing an extraction solution by dissolving an extractant in an organic solvent (S1), extracting metallic components with the organic solvent by adding the extraction solution to the waste hydrochloric acid (S2), separating a waste hydrochloric acid layer and the organic solvent containing the metallic components (S3), and obtaining purified hydrochloric acid by recovering the separated (fractionated) waste hydrochloric acid layer (S4), wherein the extractant is used in an amount of 40 moles or more based on 1 mole of iron (Fe) included in the waste hydrochloric acid, and the waste hydrochloric acid and the extraction solution are mixed in a volume ratio of 1:0.1 to 1:1.

A sugar mixture comprising: monosaccharides; oligosaccharides in a ratio0.06 to total saccharides; disaccharides in a ratio to total saccharides0.05; pentose in a ratio to total saccharides0.05; at least one alpha-bonded di-glucose; and at least one beta-bonded di-glucose. Also disclosed are methods to make and/or use such mixtures.

A process is described for removing halogen compounds, particularly chlorine compounds, from a process fluid, comprising 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.

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.