摘要:
The present invention relates to a process for the preparation of isocyanates by reacting the appropriate amines with phosgene, condensing the gas mixture thereby obtained, stripping the liquid phase thereby obtained and returning the solvent so retained in liquid form to the reaction stage. The gaseous constituents are then purified further in an absorption process.
摘要:
The present invention relates to a process for the preparation of isocyanates by reacting the appropriate amines with phosgene, condensing the gas mixture thereby obtained, stripping the liquid phase thereby obtained and returning the solvent so retained in liquid form to the reaction stage. The gaseous constituents are then purified further in an absorption process.
摘要:
The present invention relates to a process for purifying anhydrous hydrogen chloride gas (“aHCl”), and preferably the anhydrous hydrogen chloride gas recovered from an isocyanate production process. In the process of the present invention, the content of chlorinated organics may be reduced from up to 1000 ppm by volume to below 10 ppb by volume levels. Generally, the process of the invention allows for chlorinated organic levels to be reduced to from 1 to 100 ppb, rendering the treated hydrogen chloride gas usable in a catalytic oxychlorination process or a Deacon process. The treated gas is also suitable for absorption in water or dilute hydrochloric acid.
摘要:
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. The organic phase and the aqueous acid phase containing sulfuric acid were then separated, and the aqueous acid phase containing sulfuric acid was concentrated by vacuum evaporation. The resulting concentrated sulfuric acid was recycled into the reaction in the first stage and/or the second stage.