Abstract: The invention relates to a method for continuous production of nitrobenzene by means of nitration of benzene with nitric acid and sulfuric acid, in which load change (i.e. a reduction or increase in the quantity of nitric acid supplied to the process per time interval) is particularly advantageously developed. The invention particularly relates to a method in which, in the case of a load reduction, the ratio of the masses of benzene and nitric acid supplied per time interval is significantly increased compared to said ratio before the load change and/or the ratio of the masses of nitric acid and sulfuric acid supplied per time interval is significantly reduced compared to said ratio before the load change. In the event of a load increase, the reverse is carried out.

Abstract: The invention relates to a method for continuous production of nitrobenzene by means of nitration of benzene with nitric acid and sulfuric acid, in which load change (i.e. a reduction or increase in the quantity of nitric acid supplied to the process per time interval) is particularly advantageously developed. The invention particularly relates to a method in which, in the case of a load reduction, the ratio of the masses of benzene and nitric acid supplied per time interval is significantly increased compared to said ratio before the load change and/or the ratio of the masses of nitric acid and sulfuric acid supplied per time interval is significantly reduced compared to said ratio before the load change. In the event of a load increase, the reverse is carried out.

Abstract: The invention relates to a method for producing dinitrotoluene, comprising the following steps: a) nitrating toluene with a mixture of nitric acid and sulfuric acid and subsequently separating a sulfuric-acid-containing aqueous phase that arises in the nitration, wherein a raw dinitrotoluene is obtained, b) washing the raw dinitrotoluene in a water wash with neutral and/or alkaline washing water, wherein a pre-cleaned dinitrotoluene, which contains at least water in addition to dinitrotoluene, is obtained after the washing water used in the last wash has been separated, and c) separating the water from the pre-cleaned dinitrotoluene, d) collecting the waste water from steps a), b), and/or c), e) optionally extracting the collected waste water from step d) with toluene and returning the thus obtained organic phase to step a), f) freeing the collected waste water from step d), or, if the optional step e) is performed, the extracted waste water from step e), of toluene in a toluene stripper, wherein a toluene-co

Abstract: The invention relates to a method for producing dinitrotoluene, comprising the following steps: a) nitrating toluene with a mixture of nitric acid and sulfuric acid and subsequently separating a sulfuric-acid-containing aqueous phase that arises in the nitration, wherein a raw dinitrotoluene is obtained, b) washing the raw dinitrotoluene in a water wash with neutral and/or alkaline washing water, wherein a pre-cleaned dinitrotoluene, which contains at least water in addition to dinitrotoluene, is obtained after the washing water used in the last wash has been separated, and c) separating the water from the pre-cleaned dinitrotoluene, d) collecting the waste water from steps a), b), and/or c), e) optionally extracting the collected waste water from step d) with toluene and returning the thus obtained organic phase to step a), f) freeing the collected waste water from step d), or, if the optional step e) is performed, the extracted waste water from step e), of toluene in a toluene stripper, wherein a toluene-co

Abstract: The present invention relates to a continuous process for the production of nitrobenzene by nitration of benzene with nitric acid or mixtures of nitric acid and sulfuric acid to give a crude nitrobenzene, washing of the crude nitrobenzene by means of at least one of each of an acid, alkaline and neutral washing, there being obtained a pre-purified nitrobenzene which, as well as containing nitrobenzene, at least contains also low boilers, optionally middle boilers as well as high boilers and salts, wherein the pre-purified nitrobenzene is purified further by separating off low boilers in a distillation apparatus by evaporation of the low boilers, and separation of nitrobenzene from the resulting further purified nitrobenzene in a distillation apparatus by partial evaporation of nitrobenzene, wherein pure nitrobenzene is removed from the distillation apparatus in gaseous form and is subsequently condensed, and wherein the non-evaporated portion of the further purified nitrobenzene is fed back into the washing a

Abstract: Nitrobenzene is continuously produced by nitration of benzene with mixed acid under adiabatic conditions. In this process, the pressure upstream of the nitration reactor is from 14 bar to 40 bar above the pressure in the gas phase of the phase separation apparatus used to separate crude nitrobenzene and waste acid.

Abstract: Dinitrotoluene is produced by nitration of toluene with nitrating acid (mixture of nitric acid and sulfuric acid) in which, in a first stage, the toluene is converted to mononitrotoluene (MNT) and then the mononitrotoluene is converted in a second stage to dinitrotoluene (DNT). Control of the weight ratio of the aqueous to organic phases, dispersion of the organic phase in the aqueous phase and use of less than 2.06 moles of nitric acid per mole of toluene are key features of this process.

Abstract: The invention relates to a process for the production of phosgene, in which chlorine and carbon monoxide are reacted in the presence of an activated charcoal catalyst in a shell-and-tube reactor which contains a plurality of reaction tubes and a coolant space surrounding the reaction tubes, in which a) cooling of the reaction tubes is from the outside through the coolant space with water by evaporative cooling, and b) operation of the reaction tubes is at a pressure above the pressure in the coolant space.

Abstract: Dinitrotoluene is produced by nitration of toluene with nitrating acid (mixture of nitric acid and sulfuric acid) in which, in a first stage, the toluene is converted to mononitrotoluene (MNT) and then the mononitrotoluene is converted in a second stage to dinitrotoluene (DNT). Control of the weight ratio of the aqueous to organic phases, dispersion of the organic phase in the aqueous phase and use of less than 2.06 moles of nitric acid per mole of toluene are key features of this process.

Abstract: The invention describes a stirring device made from a gassing stirrer and a liquid mixer or two liquid mixers, which are arranged on a shaft and each have a feed and at least one exit opening, wherein the exit openings of the gassing stirrer and of the liquid mixer or the liquid mixers are at a distance from one another, the ratio, a/d, of the distance, a, between the exit openings to the diameter, d, of the gassing stirrer or liquid mixer being 0.02 to 0.5 and the ratio, b/d, of the distance, b, between the outer edges to the diameter, d, of the gassing stirrer or liquid mixer being 0.01 to 0.4.

Abstract: The present invention is directed to a process for the isothermal nitration of aromatic organic compounds, wherein an aromatic organic compound is brought into contact and reacted with a mixture of sulfuric acid and nitric acid. The mixture of sulfuric acid and nitric acid, and the aromatic organic compound are brought into contact with each other through a mixing nozzle which comprises a substantially cylindrical tubular reactor and an annular gap which surrounds the tubular reactor. The aromatic organic compound flows through the tubular reactor, and the mixture of sulfuric acid and nitric acid flows through the annular gap, and they are mixed together upon emerging from the tubular reactor and the annular gap, wherein the ratio of the average rates of flow of the aromatic organic compound in the tubular reactor, and of the mixture of sulphuric acid and nitric acid in the annular gap ranges from 0.5:1 to 10:1.

Abstract: The invention relates to a process for the production of dinitrotoluene by the two-stage nitration of toluene. In the first stage of this process, toluene was reacted adiabatically with nitrating acid so that at least 90% of the toluene was reacted off and no more than 70% of the toluene formed dinitrotoluene. The resulting organic phase containing mononitrotoluene and the aqueous acid phase containing sulfuric acid were separated, and the aqueous acid phase containing sulfuric acid was concentrated by flash evaporation. The resulting concentrated sulfuric acid was recycled into the reaction in the first stage, and/or into the reaction in the second stage, and/or into the concentration in the second stage. In the second stage, the organic phase containing mononitrotoluene from the first stage was completely reacted isothermally with nitrating acid.

Abstract: The present invention relates to a process for working up organic secondary components which are formed in the one-stage or two-stage nitration of toluene to dinitrotoluene. These organic secondary components are present in the acidic and alkaline waste water from the dinitrotoluene washing step and in the aqueous distillate from the sulfuric acid concentration step, together with small amounts of mononitrotoluene and dinitrotoluene. This process comprises a) combining the acidic and alkaline waste waters from the washing step and the aqueous distillate from the sulfuric acid concentration step such that the resulting mixture has a pH below 5, b) separating the aqueous and organic phases which form by phase separation, and c) recycling the organic phase from step b) into the nitration process.

Abstract: The present invention relates to a process for working up or treating aqueous waste waters which are formed during the nitration of toluene to dinitrotoluene with nitrating acid. These aqueous waste waters containing acidic wash water and alkaline wash water from the dinitrotoluene washing step, and distillate from the sulfuric acid concentration step. The process comprises, a) combining the acidic and alkaline waste waters from the washing step and the aqueous distillate from the sulfuric acid concentration step such that the resulting mixture has a pH below 5, b) separating the aqueous and organic phases which are formed by phase separation, c) subjecting the aqueous phase from b) to an extraction step, wherein d) the organic components contained in the aqueous phase from c) are extracted with toluene, and e) introducing the toluene phase enriched with the organic components into the toluene nitration.

Abstract: A process for concentrating spent sulphuric acids particularly sulphuric acids which arise during the nitration of hydrocarbons with nitric acid in the presence of sulphuric acid, wherein single- or multi-stage concentration is effected under vacuum.