Abstract:
A process is proposed for distillatively removing dinitrotoluene from process wastewater from the preparation of dinitrotoluene by nitrating toluene with nitrating acid, which comprises basifying the process wastewater to a pH of >8.5, feeding it to a stripping column in the upper region thereof and stripping it with steam in countercurrent to obtain a vapor stream laden with dinitrotoluene and a bottom stream depleted in dinitrotoluene compared to the process wastewater used.
Abstract:
PROBLEM TO BE SOLVED: To provide a nitrobenzene production method advantageous in that water consumption is small which leads to a reduced wastewater amount, the purity of the final nitrobenzene product is high, the investment cost is low because of the possibility of dispensing with one or two washing steps depending on the desired purity, the use of adjuvants, e.g., a de-emulsifier can be avoided, and the application possibility and reliability of the method are high. SOLUTION: The production method comprises producing nitrobenzene, subsequently purifying the produced nitrobenzene with an acidic washing liquid, an alkaline washing liquid, and a neutral washing liquid, subjecting the dispersion formed by the neutral washing to electrophoresis to separate water and benzene from the nitrobenzene, and recovering the purified nitrobenzene. COPYRIGHT: (C)2007,JPO&INPIT
Abstract:
PROBLEM TO BE SOLVED: To provide a simple and economical method for removing and treating undesirable sub-components in nitration. SOLUTION: This method for removing the organic sub-components formed in the nitration is characterized (a) by combining (1) an acid or alkaline waste water produced in a cleaning process of the nitration with (2) an aqueous distillate from a sulfuric acid concentration process so as to make the mixture have
Abstract:
PROBLEM TO BE SOLVED: To provide a method for producing an aromatic amine, capable of reducing an amount of waste water occurring when the aromatic amine is produced and therefore economical. SOLUTION: This method for producing the aromatic amine comprises processes of (a) reacting an aromatic hydrocarbon with a mixture of nitric acid and sulfuric acid to form a two-phase reaction mixture, (b) separating the two-phase reaction mixture into an aqueous acid phase and an organic phase containing an aromatic nitro compound, (c) washing the organic phase to purify the aromatic nitro compound, (d) hydrogenating the aromatic nitro compound in the presence of a catalyst to produce the aromatic amine and water, and (e) separating the water produced in the process (d) from the aromatic amine, wherein the water separated in the process (e) is used for washing the organic phase containing the aromatic nitro compound in the process (c). COPYRIGHT: (C)2005,JPO&NCIPI
Abstract:
A process is provided for recovery and re-use of dinitrophenols employed as inhibitors of polymerization in the distillation and purification of styrene. The styrene still residues commonly referred to as tar or tars are treated with an aqueous hydroxide at a controlled pH, the phases are separated, the aqueous phase is treated with an acid and an organic solvent at a controlled pH and the resulting organic phase is recycled to a suitable point in the styrene purification system. The recycled solution is a more effective inhibitor than the dinitrophenol originally employed.