Abstract: A nitration reactor (10) incorporating sections of downward flow for use in preparing nitrated organic compounds. It comprises a first vertically-oriented reactor section (12), a second vertically-oriented reactor section (14), a connecting section (16) between the two reactor sections, one or more inlets (20, 22) for introducing nitration reactants into the reactor, an outlet (24) for the removal of nitration reaction products, a vertically-downward flowpath (26) for the nitration reactants in one of the reactor sections or the connecting section, and operating conditions that produce a flow regime in the vertically-downward flowpath that is a dispersed flow regime or a bubbly flow regime. The invention overcomes the limitations of prior art nitration reactors of the type in which fluids flow largely in a vertically upward direction, with respect to hydrostatic demands and plant layout considerations.

Abstract: A method of safely vaporizing liquid chlorine containing high concentrations of nitrogen trichloride contaminant from a chloralkali plant. In a vertical plug-flow vaporizer having an upward flow direction, a stream of liquid chlorine containing nitrogen trichloride is received. A gas such as air, nitrogen or chlorine gas is introduced into the liquid stream upstream of the boiling zone of the vaporizer to induce a flow regime, for example annular flow or mist flow, that prevents a mass accumulation of nitrogen trichloride in the vaporizer. The liquid chlorine containing nitrogen trichloride is vaporized. The resulting gas stream may be processed to destroy the nitrogen trichloride and recycled to the chlorine production train.

Abstract: A process for removing impurities from crude nitrated aromatic products obtained during the nitration of aromatic compounds. The nitrated aromatic products are purified by treatment with ammonia washing followed by caustic washing. The nitrophenolic-containing wash waters are treated to recover dissolved organics and ammonia, and the stripped ammonia-wash effluent is incinerated. Carbon dioxide, which can accumulate in the process, is purged to the caustic washer.

Abstract: A method and apparatus for removing non-aromatic impurities from non-nitrated aromatic reactant in a nitration production process, in which process an aromatic reactant is nitrated (100) to produce a nitrated aromatic product using a molar excess of the aromatic reactant, and non-nitrated aromatic reactant is recovered (102) from the produced nitrated aromatic product and is recycled (104) for use in the nitration production process. A portion of the removed excess non-nitrated aromatic reactant is diverted (106) and subjected to nitration (108). The nitrated stream may be further processed by separating out the spent acids (110) and the non-aromatic impurities (116). These streams may be sent (114, 118) to a suitable location in the nitration production train.

Abstract: A method of removing alkalinity and salt from a nitroaromatic product downstream of water washing to remove mineral acids and alkaline washing to remove salts of organic acids, comprises washing the product stream with an acidic aqueous solution, prior to the step of removing excess organic reactant, by steam stripping or distillation. Acid removed from the stripper or column is recycled back for use in the acidic washing. The acidic washing is done instead of the neutral washing step of the prior art. It removes residual salt and decreases the level of entrained colloidal water in the nitroaromatic product.

Abstract: A method of removing alkalinity and salt from a nitroaromatic product downstream of water washing to remove mineral acids and alkaline washing to remove salts of organic acids, comprises washing the product stream with an acidic aqueous solution, prior to the step of removing excess organic reactant, by steam stripping or distillation. Acid removed from the stripper or column is recycled back for use in the acidic washing. The acidic washing is done instead of the neutral washing step of the prior art. It removes residual salt and decreases the level of entrained colloidal water in the nitroaromatic product.

Abstract: A process for continuous adiabatic nitration of toluene to mononitrotoluene (MNT). The process yields a product quality of MNT that is comparable to that obtained by isothermal production. The process uses excess toluene, with the reaction rate being controlled to maintain a residual of 0.003-0.102 wt % nitric acid in the spent acid and an orange to red color of the spent acid. Further process conditions include re-concentrated sulfuric acid at 83 to 99 degrees C. with a concentration of sulfuric acid from 66 to 70.5 wt %. This is mixed with nitric acid to generate a mixed acid with 1.0 to 3.8 wt % nitric acid and toluene is added at a rate of 1.1 to 1.71 moles toluene/mole nitric acid. The reactants are mixed in a reactor with an overall average mixing intensity of 5.8 to 19 W/kg of contained solution.

Abstract: A process for treating wastewater containing nitro-hydroxy-aromatic compounds using oxidative sub-critical conditions. The wastewater to be treated is adjusted to contain excess hydroxide equivalent to greater than three moles of free hydroxide per mole of total nitro-hydroxy-aromatic compounds, and a sub-stoichiometric amount of an oxidant is supplied to the wastewater. The nitro-hydroxy-aromatic compounds may include nitro-phenol salts or nitro-cresol salts.

Abstract: An adiabatic process for making mononitrobenzene by the nitration of benzene which minimizes the formation of nitrophenols and dinitrobenzene by-products. The process uses a mixed acid having less than 3 wt % nitric acid, 55 to 80 wt % sulfuric acid, and water. The initial temperature of the mixed acid is in the range of 60 to 96° C. The nitration reaction is complete in about 300 seconds and produces less than 1,200 ppm nitrophenols and less than about 80 ppm dinitrobenzene. The reaction can be carried out in a plug-flow or a stirred pot reactor, or a combination of such reactors.

Abstract: A method for making mononitrobenzene using a plug flow reactor train. Benzene, nitric acid and sulfuric acid are introduced into the reactor and produced mononitrobenzene is removed at an outlet end. All of the benzene and at least part of the sulfuric acid are introduced at the inlet end of the reactor. A first portion of the nitric acid is introduced by a first nitric acid feed into the inlet end and a second portion of the nitric acid is introduced at one or more additional feeds that are spaced between the inlet end and the outlet end. The method results in reduced formation of by-product dinitrobenzene, improving the reaction yield of mononitrobenzene while avoiding the need for a distillation step.

Abstract: A process for continuous adiabatic nitration of toluene to mononitrotoluene (MNT). The process yields a product quality of MNT that is comparable to that obtained by isothermal production. The process uses excess toluene, with the reaction rate being controlled to maintain a residual of 0.003-0.102 wt % nitric acid in the spent acid and an orange to red color of the spent acid. Further process conditions include re-concentrated sulfuric acid at 83 to 99 degrees C. with a concentration of sulfuric acid from 66 to 70.5 wt %. This is mixed with nitric acid to generate a mixed acid with 1.0 to 3.8 wt % nitric acid and toluene is added at a rate of 1.1 to 1.71 moles toluene/mole nitric acid. The reactants are mixed in a reactor with an overall average mixing intensity of 5.8 to 19 W/kg of contained solution.

Abstract: A method and apparatus for removing non-aromatic impurities from non-nitrated aromatic reactant in a nitration production process, in which process an aromatic reactant is nitrated (100) to produce a nitrated aromatic product using a molar excess of the aromatic reactant, and non-nitrated aromatic reactant is recovered (102) from the produced nitrated aromatic product and is recycled (104) for use in the nitration production process. A portion of the removed excess non-nitrated aromatic reactant is diverted (106) and subjected to nitration (108). The nitrated stream may be further processed by separating out the spent acids (110) and the non-aromatic impurities (116). These streams may be sent (114, 118) to a suitable location in the nitration production train.

Abstract: A method of removing alkalinity and salt from a nitroaromatic product downstream of water washing to remove mineral acids and alkaline washing to remove salts of organic acids, comprises washing the product stream with an acidic aqueous solution, prior to the step of removing excess organic reactant, by steam stripping or distillation. Acid removed from the stripper or column is recycled back for use in the acidic washing. The acidic washing is done instead of the neutral washing step of the prior art. It removes residual salt and decreases the level of entrained colloidal water in the nitroaromatic product.

Abstract: A process for treating wastewater containing nitro-hydroxy-aromatic compounds using oxidative sub-critical conditions. The wastewater to be treated is adjusted to contain excess hydroxide equivalent to greater than three moles of free hydroxide per mole of total nitro-hydroxy-aromatic compounds, and a sub-stoichiometric amount of an oxidant is supplied to the wastewater. The nitro-hydroxy-aromatic compounds may include nitro-phenol salts or nitro-cresol salts.

Abstract: A method of safely vaporizing liquid chlorine containing high concentrations of nitrogen trichloride contaminant from a chloralkali plant. In a vertical plug-flow vaporizer having an upward flow direction, a stream of liquid chlorine containing nitrogen trichloride is received. A gas such as air, nitrogen or chlorine gas is introduced into the liquid stream upstream of the boiling zone of the vaporizer to induce a flow regime, for example annular flow or mist flow, that prevents a mass accumulation of nitrogen trichloride in the vaporizer. The liquid chlorine containing nitrogen trichloride is vaporized. The resulting gas stream may be processed to destroy the nitrogen trichloride and recycled to the chlorine production train.

Abstract: A method of processing a stream of liquid chlorine containing nitrogen trichloride from a chloralkali plant. The liquid stream is received into a vaporizer in which it is evaporated 1O1 chlorine gas and nitrogen trichloride gas. The gas stream is processed by destroying the nitrogen trichloride gas, for example in a superheater or a catalytic bed. The processed gas stream is recycled to the chlorine production train of the chloralkali plant. The process avoids the use of organic solvents to decompose the nitrogen trichloride and the creation of a waste stream requiring further handling.

Abstract: An adiabatic process for making mononitrobenzene by the nitration of benzene which minimizes the formation of nitrophenols and dinitrobenzene by-products. The process uses a mixed acid having less than 3 wt % nitric acid, 55 to 80 wt % sulfuric acid, and water. The initial temperature of the mixed acid is in the range of 60 to 96° C. The nitration reaction is complete in about 300 seconds and produces less than 1,200 ppm nitrophenols and less than about 80 ppm dinitrobenzene. The reaction can be carried out in a plug-flow or a stirred pot reactor, or a combination of such reactors.

Abstract: A method for making mononitrobenzene using a plug flow reactor train. Benzene, nitric acid and sulfuric acid are introduced into the reactor and produced mononitrobenzene is removed at an outlet end. All of the benzene and at least part of the sulfuric acid are introduced at the inlet end of the reactor. A first portion of the nitric acid is introduced by a first nitric acid feed into the inlet end and a second portion of the nitric acid is introduced at one or more additional feeds that are spaced between the inlet end and the outlet end. The method results in reduced formation of by-product dinitrobenzene, improving the reaction yield of mononitrobenzene while avoiding the need for a distillation step.