Abstract: The present invention concerns a process for the preparation of isocyanates and/or polyisocyanates by reacting the corresponding amines with phosgene in a reactor, where isocyanates are obtained from a mixture of amines in gaseous or liquid form and phosgene in gaseous form, wherein no liquid solvents are used in the feeding, mixing, reacting, cooling, separating and purifying steps of the process.

Abstract: The invention relates to a process for producing isocyanates by reacting the corresponding amines with phosgene in the liquid phase, comprising: (a) mixing an amine comprising feed stream, a phosgene comprising feed stream and optionally an inert solvent; (b) reacting the amine with phosgene in a first reaction section to obtain an intermediate reaction mixture comprising isocyanate, carbamoyl chlorides, amine hydrochlorides and unreacted phosgene; (c) cleaving the carbamoyl chlorides and remove phosgene from the intermediate reaction mixture in a second reaction section to obtain an isocyanate comprising crude product, (d) optionally working-up the crude product; wherein reacting (b) is carried out such that the intermediate reaction mixture comprises 1.7 to 5 mol-% solid amine hydrochlorides based on the molar amount of amine fed into the process.

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: A process for preparing an aromatic polyamine mixture including 4,4?-methylenedi(phenylamine) and higher homologues of MDA is provided. The process includes steps of (i) reaction of aniline with formaldehyde by means of an acid catalyst to form a crude product mixture (I), (ii) neutralization of the crude product mixture (I) and removal of the salts formed; (iii) isolation of aniline; (iv) distillation of the resulting crude product mixture so as to separate off (iv-1) a mixture (II) of MDA isomers (II-1) containing from 8 to 20% by weight of 4,4?-methylenedi(phenylamine) and not more than 0.3% by weight of secondary components (II-2) and (iv-2) a low boiler mixture of at least 55% by weight of secondary components (II-2) and MDA isomers (II-1); and (v) recirculation of the mixture (II).

Abstract: The present invention relates to a process for hydrogenating a mixture (G1) in the presence of a catalyst, where the mixture (G1) comprises at least one colorless amine and at least one color-imparting component. As a result of the hydrogenation step, the at least one color-imparting component is firstly partially, preferably fully, hydrogenated, while the colorless amine, in particular aniline, is not hydrogenated or hydrogenated to only a very small extent. The color-imparting components which cause the discoloration of the amine which is itself in principle colorless are thus removed by hydrogenation, as a result of which purification of the colorless amine or the mixture (G1) is achieved.

Abstract: The invention relates to a process for preparing isocyanates by reacting primary amines with phosgene in a solvent, where the solvent comprises a dialkyl carbonate.

Abstract: The present invention relates to a process for hydrogenating a mixture (G1) in the presence of a catalyst, where the mixture (G1) comprises at least one colorless amine and at least one color-imparting component. As a result of the hydrogenation step, the at least one color-imparting component is firstly partially, preferably fully, hydrogenated, while the colorless amine, in particular aniline, is not hydrogenated or hydrogenated to only a very small extent. The color-imparting components which cause the discoloration of the amine which is itself in principle colorless are thus removed by hydrogenation, as a result of which purification of the colorless amine or the mixture (G1) is achieved.

Abstract: 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.

Abstract: The invention relates to a process for preparing isocyanates by reacting primary amines with phosgene in a solvent, where the solvent comprises a dialkyl carbonate.

Abstract: The invention relates to a process for preparing isocyanates by reacting primary amines with phosgene in a solvent, where the solvent comprises a dialkyl carbonate.

Abstract: 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.

Abstract: The invention relates to a process for preparing isocyanates by reacting primary amines with phosgene in a solvent, where the solvent comprises a dialkyl carbonate.

Abstract: The invention relates to a method for purifying mixtures comprising 4,4?-methylenediphenyl diisocyanate, which comprises purifying by distillation a mixture I comprising 4,4?-methylenediphenyl diisocyanate having a hydrolyzable chlorine content as specified in ASTM D4663-10 of greater than 100 ppm by means of a column K1, wherein the gaseous stream comprising the mixture I is brought into contact in the column K1 with at least one liquid compound A which has the same or higher boiling point than 4,4?-methylenediphenyl diisocyanate and which has a hydrolyzable chlorine content as specified in ASTM D4663-10 of a maximum of 100 ppm, and wherein the gaseous stream O obtained at the top of the column comprises 4,4?-methylenediphenyl diisocyanate has a hydrolyzable chlorine content as specified in ASTM D4663-10 of a maximum of 100 ppm.

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: A method of regulating the viscosity of a mixture containing at least two components having different viscosities, which includes the steps of: (a) determination of the viscosity of the mixture via ultrasound measurements, (b) standardization of the viscosity determined to standard conditions, (c) comparison of the standardized viscosity with a prescribed intended value, and (d) adjustment of the viscosity of the mixture by increasing or decreasing the proportion of at least one component of the mixture, where the ultrasound measurements in step (a) are carried out at or in a line conveying the mixture or in a vessel.

Abstract: A process for preparing phosgene by reaction of a feed stream (1) obtained by combining and mixing a chlorine feed stream (2) and a carbon monoxide feed stream (3), with the carbon monoxide being introduced in a stoichiometric excess over chlorine, in catalyst tubes filled with beds of activated carbon in a reactor R having a bundle of catalyst tubes, to give a product gas mixture (4) which is separated into a liquid, phosgene-comprising product stream (5) and an offgas stream (6) comprising carbon monoxide which is discharged via a pressure-regulating valve, where the reaction of the feed stream (1) in the reactor R and the separation of the product gas mixture (4) are carried out under a pressure in the range from 2.0 to 6.

Abstract: The invention relates to a process for preparing methylenedi(phenyl isocyanate), which comprises (a) the phosgenation of two-ring and/or multiring methylenedi(phenylamine), (b) the fractionation of the crude methylenedi(phenyl isocyanate) obtained to give two-ring and multiring isomers, (c) the purification and/or fractionation of the resulting mixture of two-ring isomers of methylenedi(phenyl isocyanate) and (d) the storage of the mixtures obtained in step (c) or in step (b), wherein part of the stored mixtures is reused by means of recirculation in at least one of steps (b) or (c).