Abstract: 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.

Abstract: The present invention relates to a continuous process for preparing phosgene as well as a production unit for carrying out said process.

Abstract: Chemical reactor comprising an educt space with inlet means for feeding at least one educt stream into said space: a product space with outlet means for removing at least one product stream from said space: a plurality of parallel tubes extending from the educt space to the product space in an axial direction, forming a tube bundle, wherein the tubes comprise at least one heterogeneous catalyst: a cooling liquid space surrounding at least a section of the tube bundle, wherein said space has an inlet and an outlet spaced from the inlet at least in the axial direction, and wherein the cooling liquid space defines a cooling liquid flow path between inlet and outlet: n cooling liquid temperature measuring devices MD(i), i=1 . . . n, n>2, inside the cooling liquid space, wherein MD(i+1), is located upstream of MD(i) in the cooling liquid flow path.

Abstract: The invention relates to a process for the production of phosgene comprising a gas phase reaction of carbon monoxide and chlorine in the presence of a carbon catalyst in a multi-tubular reactor, wherein the carbon catalyst comprises an amount of mesopores having a pore diameter in the range of from 2 to 50 nm of at least 0.45 ml/g of the total pore volume and the use of a carbon catalyst comprising an amount of mesopores having a pore diameter in the range of from 2 to 50 nm of at least 0.45 ml/g of the total pore volume, for the production of phosgene and a reaction mixture for preparing phosgene, the mixture comprising a catalyst for preparing phosgene comprising a porous material comprising carbon, micropores and mesopores, wherein said micropores have a pore diameter of less than 2 nm and wherein said mesopores have a pore diameter in the range of from 2 to 50 nm, wherein the volume of the mesopores of the porous material is of at least 0.

Abstract: The invention relates to a process for producing phosgene by gas phase reaction of carbon monoxide and chlorine in the presence of a catalyst in a reactor that comprises a plurality of contact tubes arranged parallel to one another, which contact tubes are filled with the catalyst and around which at least one fluid heat transfer medium flows, a feed stream of a mixture of a chlorine input stream and a carbon monoxide input stream being conducted into the contact tubes and reacted to form a phosgene-containing product gas mixture, characterised in that the product gas mixture is discharged from the contact tubes at an outlet end of the contact tubes.

Abstract: The invention relates to a process for producing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a catalyst in a reactor which comprises a plurality of parallel catalyst tubes which are filled with the catalyst and around which at least one fluid heat transfer medium flows, where a feed stream of a mixture of a chlorine input stream and a carbon monoxide input stream is fed into the catalyst tubes and is allowed to react to give a phosgene-comprising product gas mixture, wherein the reaction is carried out at an area load of more than 2.75 kg of phosgene/m2s. The invention also provides a reactor for carrying out the process.

Abstract: The present invention relates to a process for preparing phosgene by reacting chlorine with carbon monoxide over an activated carbon catalyst, wherein the content of chlorine oxides in the chlorine feed stream is low, to an apparatus for preparation of phosgene and to the use of the phosgene prepared by the process of the invention.

Abstract: The invention relates to a process for the catalytic oxidation of hydrogen chloride by means of oxygen to form chlorine in a fluidized-bed process in the presence of a catalyst comprising ruthenium on a particulate support composed of alpha-aluminum oxide having an average particle size of from 10 to 200 ?m, wherein the catalyst support has a low surface roughness and can be obtained from a used catalyst which has been used in a fluidized-bed process for at least 500 hours of operation.

Abstract: The invention relates to a process for preparing methylenediphenyldiamine (MDA) by reacting formaldehyde and aniline in the presence of an acidic catalyst, wherein the oxygen content in the process for preparing MDA is <10 000 ppm, based on all compounds present in the process. The invention further relates to the phosgenation of MDA to methylenediphenyl diisocyanate (MDI).

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: The invention relates to a process for the catalytic oxidation of hydrogen chloride by means of oxygen to form chlorine in a fluidized-bed process in the presence of a catalyst comprising ruthenium on a particulate support composed of alpha-aluminum oxide having an average particle size of from 10 to 200 ?m, wherein the catalyst support has a low surface roughness and can be obtained from a used catalyst which has been used in a fluidized-bed process for at least 500 hours of operation.

Abstract: The invention relates to a process for preparing methylenediphenyldiamine (MDA) by reacting formaldehyde and aniline in the presence of an acidic catalyst, wherein the oxygen content in the process for preparing MDA is <10 000 ppm, based on all compounds present in the process. The invention further relates to the phosgenation of MDA to methylenediphenyl diisocyanate (MDI).

Abstract: Process for preparing chlorine from hydrogen chloride, which comprises the steps: a) feeding of a stream a1 comprising hydrogen chloride and of a stream a2 comprising oxygen into an oxidation zone and catalytic oxidation of hydrogen chloride to chlorine, giving a product gas stream a3 comprising chlorine, water, oxygen, carbon dioxide and inert gases; b) contacting of the product gas stream a3 with aqueous hydrochloric acid I in a phase contact apparatus and partial separation of water and of hydrogen chloride from the stream a3, leaving a gas stream b comprising hydrogen chloride, chlorine, water, oxygen, carbon dioxide and possibly inert gases, with at least 5% of the hydrogen chloride comprised in the stream a3 remaining in the gas stream b; c) drying of the gas stream b) to leave a gas stream c which is substantially free of water and comprises hydrogen chloride, chlorine, oxygen, carbon dioxide and possibly inert gases; d) partial liquefaction of the gas stream c by compression and cooling, giving an at

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 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: 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: A process is provided for preparing light-colored isocyanates which can be used for preparing urethane compounds, in particular polyurethanes, for example polyurethane foams.

Abstract: In a process for preparing mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a reduced content of chlorinated by-products and a reduced iodine color number by two-stage reaction of the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylenepolyamines with phosgene in the presence of at least one inert organic solvent at elevated temperature, separation of the excess phosgene and solvent after the phosgenation is complete and thermal treatment of the reaction product, the mass ratios of phosgene to hydrogen chloride in the residence time apparatus of the second stage of the phosgenation are at the same time 10-30:1 in the liquid phase and 1-10:1 in the gas phase.