Abstract: This invention relates to a process for preparing chlorine from HCl and a method of using liquid HCl to cool and optionally liquefy chlorine in the process. The process involves introducing at least one HCl-containing stream and an oxygen-containing stream into an oxidation zone and catalytically oxidizing the HCl to chlorine, contacting the chlorine with aqueous HCl with partial separation of water and HCl to yield a gas stream, drying the gas stream to yield an essentially water-free gas stream, which is compressed and cooled to give an at least partially liquefied stream, and separating the liquefied stream into a gas stream and a liquid stream which is separated into a chlorine stream, such that cooling and partial liquefaction of the gas stream is effected by indirect heat exchange with a liquid HCl stream, resulting in some of the liquid HCl stream vaporizing to form a gaseous HCl stream.

Abstract: The invention relates to a process for separating chlorine from a gas stream I comprising oxygen and chlorine, in which the gas stream I is fed into a lower part of a column K1 and a separately provided liquid, hydrogen chloride stream II is fed into an upper part of the same column and the ascending gaseous stream I is brought into contact with the descending liquid stream II, with chlorine condensing out from the stream I and hydrogen chloride vaporizing from the stream II to give an essentially chlorine-free gas stream III comprising hydrogen chloride and oxygen and a liquid stream IV comprising chlorine.

Abstract: An arrangement for carrying out chemical reactions comprises at least one distillation column and/or at least one container and at least one circulation evaporator, which are connected to one another via connecting elements, liquid being taken off completely or partly from a tray or from a stacked packing bed or from a dumped packing bed or from a liquid collector of the distillation column or being fed as an external feed stream below the lower tube sheet of the circulation evaporator to said evaporator.

Abstract: The invention provides a process for the simultaneous preparation of 4,4?-diphenylmethanediamine and also diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanates, which comprises the steps a) preparation of a mixture of diphenylmethanediamine and polyphenylenepolymethylenepolyamines by acid condensation of aniline and formaldehyde and sub-sequent work-up of the mixture, b) splitting-off of part of the mixture prepared in step a), c) distillation of the mixture separated off in step b) in a column, d) recirculation of the bottom product from step c) to the end product from step a) and condensation of the overhead product from step c), e) distillation of the overhead product from step c) in a column, f) recirculation of the overhead product from step e) to the end product from step a), g) isolation of the 4,4?-diphenylmethanediamine obtained as bottom product in step e), h) reaction of the mixture from step a) with phosgene and subsequent work-up of the reaction product.

Abstract: The invention relates to a process for separating hydrogen chloride and phosgene, which comprises bringing a mixture of hydrogen chloride and phosgene into contact with an ionic liquid in which at least part of the hydrogen chloride is dissolved in a step a) and then separating off the hydrogen chloride dissolved in the ionic liquid in a step b).

Abstract: A process for the preparation of isocyanates by reacting amines with phosgene, the phosgene-containing stream of starting materials (i) being substantially free of isocyanates and (ii) having a mass content of hydrogen chloride (referred to below as HCl) of less than 0.4% by mass, and a production plant for carrying out the process according to the invention.

Abstract: Isocyanates are prepared by a process in which a product stream from the isocyanate synthesis is purified.

Abstract: Isocyanates are prepared by a process in which a product stream from the isocyanate synthesis is purified.

Abstract: The invention relates to a process for the partial or complete separation of a mixture comprising hydrogen chloride and phosgene, possibly solvents and possibly low boilers and inerts as are typically obtained in the preparation of isocyanates by reaction of amines with phosgene, which comprises firstly carrying out a partial or complete condensation of phosgene, then a distillation or stripping step in a column to remove the hydrogen chloride from the bottom product phosgene and subsequently a scrub of the top product hydrogen chloride by means of the process solvent to absorb the phosgene in the process solvent. An after-purification by means of adsorption on activated carbon or by another suitable method can subsequently be carried out to remove solvent residues.

Abstract: The invention provides a process for preparing isocyanates by reacting amines with phosgene, wherein the phosgene-containing feed stream has a hydrogen chloride content of more than 0.8% by mass.

Abstract: The present invention relates to a process for preparing isocyanates by reaction of amines with phosgene in a reactor and subsequent separation of the isocyanate from the reaction mixture leaving the reactor and purification of the isocyanate, wherein the separation and purification of the isocyanate is carried out in a column having a pressure at the top of 1-950 mbar, preferably 5-50 mbar, particularly preferably 10-20 mbar, and a temperature at the bottom of 90-250° C., preferably 120-170° C., particularly preferably 130-150° C., and the pure isocyanate stream is preferably taken off in liquid or gaseous form at a side offtake of the column.

Abstract: Isocyanates are prepared by reacting primary amines with phosgene in a reactor by a process in which a reaction discharge is present in the form of a suspension which contains the isocyanate to be prepared, as a liquid, and carbamyl chlorides as a solid, and the suspension is worked up in a film evaporator, and this process is carried out in a production plant.

Abstract: The invention relates to a process for preparing isocyanates by reaction of amines with phosgene in the presence of inert organic solvents in a reactor and subsequent work-up of the reaction mixture leaving the reactor, wherein the solvent is separated off in a two-stage or multistage, preferably two-stage, distillation process in which the solvent is separated off at a pressure of 0.1-15 bar in a first apparatus and at 1-900 mbar in a second apparatus or further apparatuses, with the heat of condensation of the solvent vapor from the first apparatus being used for partial or complete vaporization of solvent in the second apparatus.

Abstract: An arrangement for carrying out chemical reactions comprises at least one distillation column and/or at least one container and at least one circulation evaporator, which are connected to one another via connecting elements, liquid being taken off completely or partly from a tray or from a stacked packing bed or from a dumped packing bed or from a liquid collector of the distillation column or being fed as an external feed stream below the lower tube sheet of the circulation evaporator to said evaporator.