Abstract: Disclosed herein is a method for aramid polymerization using carbon dioxide as a solvent, comprising reacting phenylenediamine with benzenedicarbonyl dichloride, wherein an acid-binding agent is added to the reaction system, and liquid carbon dioxide and/or a supercritical carbon dioxide fluid is used as a reaction solvent. The method of the present application is environmentally friendly, saves resources, has low cost, and is safe for production and suitable for industrial production. The polycondensate obtained in the present application has a controllable molecular weight, a good product quality, and an intrinsic viscosity ?inh of 8-9 dl/g. The yield in the aramid condensation stage can reach 98%, and the recovery rate of the aramid condensation solvent is higher than 90%.

Abstract: Disclosed herein is a method for aramid polymerization using carbon dioxide as a solvent, comprising reacting phenylenediamine with benzenedicarbonyl dichloride, wherein an acid-binding agent is added to the reaction system, and liquid carbon dioxide and/or a supercritical carbon dioxide fluid is used as a reaction solvent. The method of the present application is environmentally friendly, saves resources, has low cost, and is safe for production and suitable for industrial production. The polycondensate obtained in the present application has a controllable molecular weight, a good product quality, and an intrinsic viscosity ?inh of 8-9 dl/g. The yield in the aramid condensation stage can reach 98%, and the recovery rate of the aramid condensation solvent is higher than 90%.

Abstract: A method for preparing chlorine gas through catalytic oxidation of hydrogen chloride is carried out by one-time hydrogen chloride feeding and multi-stage oxygen feeding, one-time oxygen feeding and multi-stage hydrogen chloride feeding, or both, returning a product gas stream without separation thereof, and optionally carrying out heat insulation means. In the present invention, excessive reaction heat concentration is prevented, therefore, the method of the present invention is a chlorine gas recovery method implemented through the Deacon catalytic oxidation of hydrogen chloride that may be industrialized.

Abstract: Clean process for preparing a chloroformyl-substituted benzene by oxidation of a tail gas hydrogen chloride from a chlorination reaction and a chloroacylation reaction and recycling of the resulting oxidation product chlorine gas into the chlorination reaction. The present invention provides a clean process for preparing a polymer-grade chloroformyl-substituted benzene.

Abstract: Clean process for preparing a chloroformyl-substituted benzene by oxidation of a tail gas hydrogen chloride from a chlorination reaction and a chloroacylation reaction and recycling of the resulting oxidation product chlorine gas into the chlorination reaction. The present invention provides a clean process for preparing a polymer-grade chloroformyl-substituted benzene.

Abstract: A method for preparing chlorine gas through catalytic oxidation of hydrogen chloride is carried out by one-time hydrogen chloride feeding and multi-stage oxygen feeding, one-time oxygen feeding and multi-stage hydrogen chloride feeding, or both, returning a product gas stream without separation thereof, and optionally carrying out heat insulation means. In the present invention, excessive reaction heat concentration is prevented, therefore, the method of the present invention is a chlorine gas recovery method implemented through the Deacon catalytic oxidation of hydrogen chloride that may be industrialized.

Abstract: The present application relates to a method for photochlorination, and specifically to photochlorination by a photochemical reaction of an aromatic compound with gaseous chlorine so as to prepare a trichloromethyl-substituted benzene, and to a method using bis-(trichloromethyl)-benzene as the trichloromethyl-substituted benzene to prepare by further reaction bis-(chloroformyl)-benzene. Through the control of temperature, illuminance and consumption of gaseous chlorine, the method of this application can greatly improve the purity of trichloromethyl-substituted benzene and further prepare polymer-grade bis-(chloroformyl)-benzene with low cost. The present application also relates to a method for purifying trichloromethyl-substituted benzene, and specifically to a method for purifying trichloromethyl-substituted benzene via molecular distillation. The present application further relates to a photochlorination reactor for use in photochlorination reactions (such as those of the present application).

Abstract: The present application relates to a method for photochlorination, and specifically to photochlorination by a photochemical reaction of an aromatic compound with gaseous chlorine so as to prepare a trichloromethyl-substituted benzene, and to a method using bis-(trichloromethyl)-benzene as the trichloromethyl-substituted benzene to prepare by further reaction bis-(chloroformyl)-benzene. Through the control of temperature, illuminance and consumption of gaseous chlorine, the method of this application can greatly improve the purity of trichloromethyl-substituted benzene and further prepare polymer-grade bis-(chloroformyl)-benzene with low cost. The present application also relates to a method for purifying trichloromethyl-substituted benzene, and specifically to a method for purifying trichloromethyl-substituted benzene via molecular distillation. The present application further relates to a photochlorination reactor for use in photochlorination reactions (such as those of the present application).

Abstract: A process for preparing alkylated p-phenylenediamine having the steps of reacting aniline and nitrobenzene in presence of a complex base catalyst to obtain 4-aminodiphenylamine intermediates, hydrogenating the 4-aminodiphenylamine intermediates to 4-aminodiphenylamine in presence of a hydrogenation catalyst, and reductively alkylating the 4-aminodiphenylamine to alkylated p-phenylenediamine.

Abstract: A method for refining an organic composition containing 4-aminodiphenylamine, aniline, azobenzene, and phenazine, having the steps of feeding the organic composition to a first rectification column, producing a first effluent composition containing aniline, azobenzene, phenazine, and a small amount of 4-aminodiphenylamine at the top of the first rectification column and a second effluent composition containing crude 4-aminodiphenylamine at the bottom of the first rectification column, feeding the second effluent composition to a second rectification column, and producing a 4-aminodiphenylamine composition at the top of the second rectification column and a residual composition at the bottom of the second rectification column.

Abstract: A falling film evaporator having a shell pass, multiple tubes parallel to each other, a condensed steam outlet, an inlet for an aqueous solution on the top of the tube pass, an outlet for the aqueous solution at the bottom of the tube pass, a distributing assembly having a plurality of distributing trays arranged vertically from top to bottom in incremental diameters and each having multiple holes, and a plate for collecting the aqueous solution below the distributing assembly. The tubes are straight and installed vertically in the evaporator; inner wall of the tubes is smooth, and the top portion of the tubes is protruded above a horizontal plane of the plate. The evaporator is particularly useful for concentrating an aqueous solution containing thermosensitive materials.

Abstract: A process for preparing alkylated p-phenylenediamine having the steps of reacting aniline and nitrobenzene in presence of a complex base catalyst to obtain 4-aminodiphenylamine intermediates, hydrogenating the 4-aminodiphenylamine intermediates to 4-aminodiphenylamine in presence of a hydrogenation catalyst, and reductively alkylating the 4-aminodiphenylamine to alkylated p-phenylenediamine.

Abstract: The present invention provides spherical rubber chemicals and the method for preparing the same. The spherical rubber chemicals of the present invention include spherical antioxidants, spherical vulcanization agents, spherical processing aids, spherical reinforcing agents, or spherical adhesive agents. With the spherical rubber chemicals of the present invention, the shortcomings of powdery or semi-spherical rubber chemicals are overcome, including eliminating the dust pollution during granulation procedure and avoiding the raw material loss and the environmental pollution, while solving the quality problem of lower melting point of product caused by the presence of fine powder crystal. Furthermore, the resultant rubber chemicals has an improved smoothness of surface, which is helpful to improve the flowing and mixing behaviors of the rubber chemicals in mixing or open milling process with rubbers.

Abstract: A complex base catalyst comprising tetraalkyl ammonium hydroxide and tetraalkyl ammonium salt for the condensation reaction of aniline and nitrobenzene.

Abstract: The present invention relates to a magnetic separation apparatus for continuous separating and recovering magnetic solid particles from a solid-liquid mixture. The apparatus includes at least one magnetic separation unit and each unit includes: an outer cylindrical vessel having a material inlet, a first outlet, and a second outlet; an inner cylindrical vessel, at least part of which extends along the axis inside the first cylindrical vessel without contacting with the inner surface of the outer cylindrical vessel; and a magnet, rendering the bottom of the inner cylindrical vessel magnetism during the first period and making the part of the surface lose its magnetism during a second period. When the solid-liquid mixture flows through the magnetic surface of the inner cylindrical vessel in the passage, the magnetic solids are absorbed and separated from the mixture.

Abstract: The present invention provides spherical rubber chemicals and the method for preparing the same. The spherical rubber chemicals of the present invention include spherical antioxidants, spherical vulcanization agents, spherical processing aids, spherical reinforcing agents, or spherical adhesive agents. With the spherical rubber chemicals of the present invention, the shortcomings of powdery or semi-spherical rubber chemicals are overcome, including eliminating the dust pollution during granulation procedure and avoiding the raw material loss and the environmental pollution, while solving the quality problem of lower melting point of product caused by the presence of fine powder crystal. Furthermore, the resultant rubber chemicals has an improved smoothness of surface, which is helpful to improve the flowing and mixing behaviors of the rubber chemicals in mixing or open milling process with rubbers.

Abstract: A method for refining an organic composition containing 4-aminodiphenylamine, aniline, azobenzene, and phenazine, having the steps of feeding the organic composition to a first rectification column, producing a first effluent composition containing aniline, azobenzene, phenazine, and a small amount of 4-aminodiphenylamine at the top of the first rectification column and a second effluent composition containing crude 4-aminodiphenylamine at the bottom of the first rectification column, feeding the second effluent composition to a second rectification column, and producing a 4-aminodiphenylamine composition at the top of the second rectification column and a residual composition at the bottom of the second rectification column.

Abstract: The present invention provides spherical rubber chemicals and the method for preparing the same. The spherical rubber chemicals of the present invention include spherical antioxidants, spherical vulcanization agents, spherical processing aids, spherical reinforcing agents, or spherical adhesive agents. With the spherical rubber chemicals of the present invention, the shortcomings of powdery or semi-spherical rubber chemicals are overcome, including eliminating the dust pollution during granulation procedure and avoiding the raw material loss and the environmental pollution, while solving the quality problem of lower melting point of product caused by the presence of fine powder crystal. Furthermore, the resultant rubber chemicals has an improved smoothness of surface, which is helpful to improve the flowing and mixing behaviors of the rubber chemicals in mixing or open milling process with rubbers.

Abstract: A falling film evaporator having a shell pass, multiple tubes parallel to each other, a condensed steam outlet, an inlet for an aqueous solution on the top of the tube pass, an outlet for the aqueous solution at the bottom of the tube pass, a distributing assembly having a plurality of distributing trays arranged vertically from top to bottom in incremental diameters and each having multiple holes, and a plate for collecting the aqueous solution below the distributing assembly. The tubes are straight and installed vertically in the evaporator; inner wall of the tubes is smooth, and the top portion of the tubes is protruded above a horizontal plane of the plate. The evaporator is particularly useful for concentrating an aqueous solution containing thermosensitive materials.

Abstract: A process for preparing 4-aminodiphenylamine having the steps of reacting nitrobenzene and aniline in the presence of a complex base catalyst, hydrogenating the reaction mixture with hydrogen, a powdery composite catalyst, and a hydrogenation solvent; separating, recovering, and reusing the complex base catalyst and the powdery composite catalyst from the reaction mixture; separating, recovering, and reusing aniline, and optionally water, from the reaction mixture; refining the reaction mixture to obtain 4-aminodiphenylamine. The complex base catalyst comprises tetraalkyl ammonium hydroxide, and tetraalkyl ammonium salt.