Process for preparing dinitrotoluene by reacting toluene with concentrated nitric acid. The process reacts toluene with a large excess of concentrated nitric acid at selected conditions to produce a product which has substantially reduced by-product content.

A process for preparing dinitrotoluene

Procedure for continuous production of nitrobenzene, comprises adiabatic nitration of benzene with a mixture of sulfuric acid and nitric acid, where the sum of the concentration of the hardly soluble metal sulfate forming metal ions in the reaction zone is less than 900 mg/l, based on the volume of aqueous phase containing sulfuric acid.

Method for manufacturing Nitrobenzol through adiabatic nitration

Methods and systems for preparing alkylene glycols are described herein. The methods and systems incorporate the novel use of a high shear device to promote dispersion and solubility of alkylene oxides with water. The high shear device may allow for lower reaction temperatures and pressures and may also reduce reaction time.

Method of making alkylene glycols

The present invention provides a continuous process for the production of nitrobenzene by nitration of benzene with mixtures of sulfuric and nitric acid using a stoichiometric excess of benzene, in which the content of aliphatic organic compounds in the feed benzene during the start-up period of the production plant is always maintained at less than 1.5 wt. %, based on the total mass of the feed benzene. This is achieved either by mixing the feed benzene comprising recycled unreacted benzene (recycled benzene) and benzene newly supplied to the reaction (fresh benzene) in appropriate quantitative ratios during the start-up period, depending on the purity of the two streams, or by completely omitting the recycling of unreacted benzene during the start-up period, i.e. the feed benzene consists only of benzene newly supplied to the reaction.

Process for the preparation of nitrobenzene by adiabatic nitration

Adiabatic nitration of benzene, comprises: (a) reacting nitric acid (1) and benzene (2) in a reactor in presence of sulfuric acid (3) to obtain nitrobenzene; (b) separating the hot reaction mixture in a separator; (c) concentrating the diluted sulfuric acid obtained during the reaction; (d) cooling the crude nitrobenzene (5); (e) purifying the crude nitrobenzene in a multi-step washing process; and (f) distilling the washed nitrobenzene to separate the low boilers and remaining water. The separation of crude nitrobenzene and sulfuric acid is carried out under pressure. Adiabatic nitration of benzene, comprises: (a) reacting nitric acid (1) and benzene (2) in a reactor in presence of sulfuric acid (3) to obtain nitrobenzene; (b) separating the hot reaction mixture in a separator; (c) concentrating the diluted sulfuric acid obtained during the reaction; (d) cooling the crude nitrobenzene (5); (e) purifying the crude nitrobenzene in a multi-step washing process; and (f) distilling the washed nitrobenzene to separate the low boilers and remaining water. The separation of crude nitrobenzene and sulfuric acid is carried out under pressure. The pressure is maintained using a pressure maintaining siphon. The benzene and low boiling mixture obtained during the distillation are separated from the remaining water. A portion of the resulting benzene and the low boiling mixture are discharged and the benzene and the low boiling mixture are then recycled for nitration.

Adiabatic nitration of benzene, comprises reacting nitric acid and benzene in presence of sulfuric acid to nitrobenzene, concentrating the diluted sulfuric acid, cooling and purifying crude nitrobenzene and distilling washed nitrobenzene

In the production of nitrobenzene by subjecting benzene to nitration with a mixture of nitric acid and sulfuric acid, separating off the nitrobenzene formed, concentrating the sulfuric acid by evaporation and returning the concentrated sulfuric acid to the bezene nitration stage, the improvement which comprises concentrating sulfuric acid to a concentration of from 75 to 92% by evaporation in vacuo at temperatures in the range from 130° to 195° C. Thereby the energy per kg of water evaporated is drastically reduced compared to processes wherein the sulfuric acid is concentrated to a higher level, without a corresponding loss in efficiency or capacity.

Process for the production of nitrobenzene

Die vorliegende Erfindung betrifft ein Verfahren zur Herstellung von Nitrobenzol durch isotherme Nitrierung von Abtrennung des gebildeten Nitrobenzols, Eindampfung der Schwefelsaure und Ruckfuhrung der aufkonzentrierten Schwefelsaure zur Benzolnitrierung. The present invention relates to a process for the preparation of nitrobenzene by isothermal nitration of separation of the nitrobenzene formed, concentration of the sulfuric acid and recycling the concentrated sulfuric acid to the nitration of benzene.

Process for the preparation of nitrobenzene

Die vorliegende Erfindung betrifft ein Verfahren zur Herstellung von Nitrobenzol durch isotherme Nitrierung von Abtrennung des gebildeten Nitrobenzols, Eindampfung der Schwefelsaure und Ruckfuhrung der aufkonzentrierten Schwefelsaure zur Benzolnitrierung.

Wolfgang Dr. Larbig

Papers

Process for the production of nitrobenzene

Process for the preparation of nitrobenzene

Verfahren zur herstellung von nitrobenzol