Abstract: The invention relates to a method for producing isocyanates by reacting primary amines with phosgene in a stoichiometric excess in the gas phase, wherein the excess phosgene is subsequently recovered and recirculated back into the reaction. The present invention relates in particular to a method for the feedback-controlled recirculation of the recovered phosgene, particularly when the phosgene stream that should be recovered is distributed between multiple gas-phase reactors operated in parallel.

Abstract: The present invention relates to a process for purifying raw-material gases by fractionation. In particular, the present invention relates to a process for cleansing chlorine gas of bromine.

Abstract: The present invention relates to a process for purifying raw-material gases by fractionation. In particular, the present invention relates to a process for cleansing chlorine gas of bromine.

Abstract: The present invention relates to a process for purifying raw-material gases by fractionation. In particular, the present invention relates to a process for cleansing chlorine gas of bromine.

Abstract: The present invention relates to a process for separating an isocyanate prepared by reaction of a primary amine with an excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, wherein (i) the gaseous crude product is partially liquefied by contacting with a quenching liquid, (ii) the gas phase obtained in step (i) is partially condensed, (iii) the condensate obtained in step (ii) is used as the quenching liquid in step (i), (iv) the portions of the gas phase that were not condensed in step (ii) are at least partially liquefied, (v) the liquid phase obtained in step (iv) is likewise used as the quenching liquid in step (i), and (vi) the liquid phase obtained in step (i) is worked up to the pure isocyanate without previously being used as quenching liquid.

Abstract: This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is shut down by first stopping the amine stream and still maintaining the phosgene stream. After a period of time which corresponds to at least 10 times the residence time of phosgene (1) in the main parts of the gas phase phosgenation plant (100) in regular operation, calculated from the time at which the amine inflow has been completely stopped, the feed of phosgene is also stopped. An inert gas stream (3) is maintained through the amine and phosgene feeding devices and through all the other essential parts of the gas phase phosgenation plant (100) during the shutdown.

Abstract: This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is started up by first charging the plant with phosgene. At the same time as, or after the first charge of phosgene, the amine supply devices are rendered inert using a hot inert gas stream (30). Then, amine is admixed for the first time. In this way and by maintaining a pressure drop in the amine and phosgene devices to the mixing zone, the back mixing of phosgene into the amine-containing reactant stream during start-up is prevented.

Abstract: The present invention relates to a process for obtaining organic isocyanate from a phosgenation product comprising the isocyanate, comprising the following steps: a) workup to the phosgenation product, the workup comprising at least one distillation step in which a first portion of the organic isocyanate is removed as distillate and a distillation residue comprising a second portion of the organic isocyanate is obtained, b) workup of the distillation residue obtained in a), the workup comprising at least one distillation step which is conducted at a temperature of up to 110° C. at a pressure of not more than 1 mbar, wherein at least 50% by weight of the second portion of the organic isocyanate is removed from the distillation residue.

Abstract: This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is started up by first charging the plant with phosgene. At the same time as, or after the first charge of phosgene, the amine supply devices are rendered inert using a hot inert gas stream (30). Then, amine is admixed for the first time. In this way and by maintaining a pressure drop in the amine and phosgene devices to the mixing zone, the back mixing of phosgene into the amine-containing reactant stream during start-up is prevented.

Abstract: This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is shut down by first stopping the amine stream and still maintaining the phosgene stream. After a period of time which corresponds to at least 10 times the residence time of phosgene (1) in the main parts of the gas phase phosgenation plant (100) in regular operation, calculated from the time at which the amine inflow has been completely stopped, the feed of phosgene is also stopped. An inert gas stream (3) is maintained through the amine and phosgene feeding devices and through all the other essential parts of the gas phase phosgenation plant (100) during the shutdown.

Abstract: The invention relates to a device (R) for producing phosgene by reacting chlorine and carbon monoxide in the presence of a fixed-bed catalyst, comprising a) a tube bundle, which is arranged inside a reactor jacket (4) and which has a plurality of reaction tubes (3), which are arranged substantially parallel to each other and which extend from a lower tube sheet (2) to an upper tube sheet (2), and b) a coolant space for a cooling fluid, which coolant space surrounds the reaction tubes (3) and is defined by the lower tube sheet (1), the upper tube sheet (2), and the reactor jacket (4), wherein the device is characterized in that the tube bundle is enclosed by an annular-space sheet (7), which defines an inner annular space (12) for the passage of the cooling fluid and which is arranged at a distance from both the lower tube sheet (1) and the upper tube sheet (2), wherein an outer annular space (13) for feeding liquid cooling fluid through is formed between the annular-space sheet (7) and the reactor jacket (4),

Abstract: The invention relates to a method for producing an isocyanate by reacting the corresponding primary amine with phosgene in a reactor (100) which comprises at least one reaction zone (110) and a quenching zone (120) arranged below said reaction zone, having the following steps: (i) introducing a gaseous amine flow (1) and a gaseous phosgene flow (2) into the reactor (100) and reacting the flows in the reaction zone (110) into a product gas flow (3) comprising isocyanate and hydrogen chloride and optionally excess phosegene; (ii) introducing the product gas flow (3) into the quenching zone (120), in which the product gas flow is cooled by injecting a quenching liquid (4) via at least one quenching nozzle (200) such that a liquid flow (5) comprising the quenching liquid (4) and isocyanate and a gaseous flow (6) comprising hydrogen chloride and optionally phosgene are obtained; and (iii) separating the isocyanate from the liquid flow (5) obtained in step (ii); wherein the temperature Tw*, of the wall of the react

Abstract: Meta-toluene-diisocyanate is produced by reacting meta-toluenediamine with phosgene in the gas phase. The meta-toluenediamine to be vaporized for use in this phosgenation process must contain less than 0.5 wt. % of toluenediamine residue, a total of less than 0.2 wt. % of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals. At least 0.1 wt. % of the liquid meta-toluenediamine being to be vaporized must not be vaporized. This non-vaporized content of the meta-toluenediamine must not be fed to the phosgenation reactor.

Abstract: The present invention relates to a process for obtaining organic isocyanate from a phosgenation product comprising the isocyanate, comprising the following steps: a) workup to the phosgenation product, the workup comprising at least one distillation step in which a first portion of the organic isocyanate is removed as distillate and a distillation residue comprising a second portion of the organic isocyanate is obtained, b) workup of the distillation residue obtained in a), the workup comprising at least one distillation step which is conducted at a temperature of up to 110° C. at a pressure of not more than 1 mbar, wherein at least 50% by weight of the second portion of the organic isocyanate is removed from the distillation residue.

Abstract: The invention relates to a method for producing an isocyanate by reacting the corresponding primary amine with phosgene in a reactor (100) which comprises at least one reaction zone (110) and a quenching zone (120) arranged below said reaction zone, having the following steps: (i) introducing a gaseous amine flow (1) and a gaseous phosgene flow (2) into the reactor (100) and reacting the flows in the reaction zone (110) into a product gas flow (3) comprising isocyanate and hydrogen chloride and optionally excess phosgene; (ii) introducing the product gas flow (3) into the quenching zone (120), in which the product gas flow is cooled by injecting a quenching liquid (4) via at least one quenching nozzle (200) such that a liquid flow (5) comprising the quenching liquid (4) and isocyanate and a gaseous flow (6) comprising hydrogen chloride and optionally phosgene are obtained; and (iii) separating the isocyanate from the liquid flow (5) obtained in step (ii); wherein the temperature Tw*, of the wall of the reacti

Abstract: The present invention relates to a process for purifying raw-material gases by fractionation. In particular, the present invention relates to a process for cleansing chlorine gas of bromine.

Abstract: The invention relates to a novel method for producing polyisocyanurates comprising isocyanate groups, based on 2,4- and 2,6-toluylene diisocyanate (TDI) and to the use thereof in coating compositions.

Abstract: The invention relates to polyisocyanates comprising urethane groups, based on toluylene diisocyanate, to a method for their production, and to their use as the polyisocyanate component in one- and two-component polyurethane coatings.

Abstract: The present invention relates to a process for separating an isocyanate prepared by reaction of a primary amine with an excess of phosgene in the gas phase from the gaseous crude product obtained in the reaction, wherein (i) the gaseous crude product is partially liquefied by contacting with a quenching liquid, (ii) the gas phase obtained in step (i) is partially condensed, (iii) the condensate obtained in step (ii) is used as the quenching liquid in step (i), (iv) the portions of the gas phase that were not condensed in step (ii) are at least partially liquefied, (v) the liquid phase obtained in step (iv) is likewise used as the quenching liquid in step (i), and (vi) the liquid phase obtained in step (i) is worked up to the pure isocyanate without previously being used as quenching liquid.

Abstract: The invention relates to a device (R) for producing phosgene by reacting chlorine and carbon monoxide in the presence of a fixed-bed catalyst, comprising a) a tube bundle, which is arranged inside a reactor jacket (4) and which has a plurality of reaction tubes (3), which are arranged substantially parallel to each other and which extend from a lower tube sheet (2) to an upper tube sheet (2), and b) a coolant space for a cooling fluid, which coolant space surrounds the reaction tubes (3) and is defined by the lower tube sheet (1), the upper tube sheet (2), and the reactor jacket (4), wherein the device is characterized in that the tube bundle is enclosed by an annular-space sheet (7), which defines an inner annular space (12) for the passage of the cooling fluid and which is arranged at a distance from both the lower tube sheet (1) and the upper tube sheet (2), wherein an outer annular space (13) for feeding liquid cooling fluid through is formed between the annular-space sheet (7) and the reactor jacket (4),