Abstract: A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid-state catalyst, which is provided in a plurality of catalyst tubes (2) which are arranged parallel to one another in the longitudinal direction of the reactor (1) and are welded at each of their two ends into a tube plate (3), with introduction of the starting materials at the upper end of the catalyst tubes (2) and discharge of the gaseous reaction mixture at the lower end of the catalyst tubes (2), in each case via a cap, and also with introduction and discharge facilities for a liquid heat transfer medium (7) in the space (4) between the catalyst tubes (2) within the shell, where the flow of the heat transfer medium (7) in the space (4) between the catalyst tubes (2) within the shell is meandering as a result of deflection plates (5), each alternative deflection plate (5) leaves two openings (6) having the shape of a segment of a circle free on opposite sides at the interior wall of the rea

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 present invention accordingly provides a process for preparing light-colored polyphenylene-polymethylene polyisocyanates comprising the steps (a) providing an amount of chlorine, (b) separating the chlorine provided in the step (a) to obtain a first chlorine fraction having a content of free and bound bromine and iodine of <50 ppm and a second chlorine fraction having an increased content of free and bound bromine and iodine that depends on the original amount of bromine and iodine in the chlorine provided in step (a) and the separation split, (c) reacting carbon monoxide with at least a portion of the first chlorine fraction to form a first phosgene fraction, (d) reacting carbon monoxide with at least a part of the second chlorine fraction to form a second phosgene fraction, (e) reacting at least a portion of a first phosgene fraction with at least one amine of the diphenylmethane diamine series (MDA) to form the corresponding polyphenylene-polymethylene polyisocyanate (PMDI), and (f) reacting at leas

Abstract: The present invention relates to a process for preparing light-colored polyphenylene-polymethylene-polyisocyanate (PMDI), comprising the steps (a) providing carbon monoxide and chlorine, (b) reacting carbon monoxide with chlorine to form phosgene, (c) reacting the phosgene from step (b) with at least one primary amine with the exception of mono- and polyphenylene-polymethylene polyamines with an excess of phosgene to form an at least one isocyanate containing reaction solution, and hydrogen chloride, (d) separating excess phosgene from the isocyanate-containing reaction solution obtained in step (c), (e) providing at least one polyphenylene-polymethylene polyamine, and (f) reacting at least a portion of the phosgene separated in step (d) with the at least one polyphenylene-polymethylene polyamine to form the light-colored polyphenylene-polymethylene polyisocyanate.

Abstract: A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid-state catalyst, which is provided in the catalyst tubes (2) of a bundle of catalyst tubes (2) which are arranged parallel to one another in the longitudinal direction of the reactor (1) and are welded at each of their two ends into a tube plate (3), with introduction of the starting materials at the upper end of the catalyst tubes (2) and discharge of the gaseous reaction mixture at the lower end of the catalyst tubes (2), in each case via a cap, and also with introduction and discharge facilities for a liquid heat transfer medium (6) in the intermediate space (4) between the catalyst tubes (2) , where the flow of the heat transfer medium (6) in the space (4) between the catalyst tubes (2) is guided by deflection plates (5), which leave alternating openings (7) free on opposite sides at the interior wall of the reactor, in which openings the deflection plates (5) have cutouts having the shape

Abstract: The present invention relates to a process for preparing light-coloured polyphenylene-polymethylene-polyisocyanate (PMDI), comprising the steps (a) providing carbon monoxide and chlorine, (b) reacting carbon monoxide with chlorine to form phosgene, (c) reacting the phosgene from step (b) with at least one primary amine with the exception of mono- and polyphenylene-polymethylene polyamines with an excess of phosgene to form an at least one isocyanate containing reaction solution, and hydrogen chloride, (d) separating excess phosgene from the isocyanate-containing reaction solution obtained in step (c), (e) providing at least one polyphenylene-polymethylene polyamine, and (f) reacting at least a portion of the phosgene separated in step (d) with the at least one polyphenylene-polymethylene polyamine to form the light-coloured polyphenylene-polymethylene polyisocyanate.

Abstract: The present invention accordingly provides a process for preparing light-coloured polyphenylene-polymethylene polyisocyanates comprising the steps (a) providing an amount of chlorine, (b) separating the chlorine provided in the step (a) to obtain a first chlorine fraction having a content of free and bound bromine and iodine of <50 ppm and a second chlorine fraction having an increased content of free and bound bromine and iodine that depends on the original amount of bromine and iodine in the chlorine provided in step (a) and the separation split, (c) reacting carbon monoxide with at least a portion of the first chlorine fraction to form a first phosgene fraction, (d) reacting carbon monoxide with at least a part of the second chlorine fraction to form a second phosgene fraction, (e) reacting at least a portion of a first phosgene fraction with at least one amine of the diphenylmethane diamine series (MDA) to form the corresponding polyphenylene-polymethylene polyisocyanate (PMDI), and (f) reacting at lea

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: A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid-state catalyst, which is provided in a plurality of catalyst tubes (2) which are arranged parallel to one another in the longitudinal direction of the reactor (1) and are welded at each of their two ends into a tube plate (3), with introduction of the starting materials at the upper end of the catalyst tubes (2) and discharge of the gaseous reaction mixture at the lower end of the catalyst tubes (2), in each case via a cap, and also with introduction and discharge facilities for a liquid heat transfer medium (7) in the space (4) between the catalyst tubes (2) within the shell, where the flow of the heat transfer medium (7) in the space (4) between the catalyst tubes (2) within the shell is meandering as a result of deflection plates (5), each alternative deflection plate (5) leaves two openings (6) having the shape of a segment of a circle free on opposite sides at the interior wall of the rea

Abstract: A reactor (1) for preparing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a solid-state catalyst, which is provided in the catalyst tubes (2) of a bundle of catalyst tubes (2) which are arranged parallel to one another in the longitudinal direction of the reactor (1) and are welded at each of their two ends into a tube plate (3), with introduction of the starting materials at the upper end of the catalyst tubes (2) and discharge of the gaseous reaction mixture at the lower end of the catalyst tubes (2), in each case via a cap, and also with introduction and discharge facilities for a liquid heat transfer medium (6) in the intermediate space (4) between the catalyst tubes (2) , where the flow of the heat transfer medium (6) in the space (4) between the catalyst tubes (2) is guided by deflection plates (5), which leave alternating openings (7) free on opposite sides at the interior wall of the reactor, in which openings the deflection plates (5) have cutouts having the shape