摘要:
This invention relates to a process for the continuous preparation of nitrobenzene. This process comprises the adiabatic nitration of benzene with a mixture of sulfuric acid and nitric acid, in which the sum of the concentrations in the reaction zone of the metal ions which form sparingly soluble metal sulfates is less than 900 mg/l, based on the volume of the aqueous phase which contains sulfuric acid.
摘要:
This invention relates to a process for the continuous preparation of nitrobenzene. This process comprises the adiabatic nitration of benzene with a mixture of sulfuric acid and nitric acid, in which the sum of the concentrations in the reaction zone of the metal ions which form sparingly soluble metal sulfates is less than 900 mg/l, based on the volume of the aqueous phase which contains sulfuric acid.
摘要:
The invention relates to a method for determining the isomer composition in an isocyanate isomer mixture, wherein a spectrum of the isomer mixture is recorded and the spectrum is entered into a chemometric calibration model.
摘要:
The present invention relates to a process for the production of 4,4′-diphenylmethane diisocyanate (4,4′-MDI) by acid-catalyzed condensation of aniline with formaldehyde, reaction of the mixtures of di- and polyamines obtained with phosgene to form the corresponding mixture of MDI isomers and homologues (di- and polyisocyanates of the diphenylmethane series) and subsequent separation of the mixture by distillation to form 4,4′-MDI and polymeric MDI.
摘要:
The present invention relates to an improved process for the production of carbodiimide modified organic isocyanate, preferably a polymethylene polyphenylisocyanate, and most preferably diphenylmethane diisocyanate. This process includes (1) neutralizing acidic impurities in an organic isocyanate, (2) partially carbodiimidizing isocyanate groups of the neutralized organic isocyanate, and (3) terminating the carbodiimidization reaction.
摘要:
One or more fluid streams are uniformly divided into two or more partial fluid streams in chemical apparatuses in a manner such that there is a reduced tendency to form deposits. Division of such stream(s) is achieved by using a distributor device that includes at least one plate having two or more openings which openings are rounded or chamfered on at least one side.
摘要:
The present invention relates to a process for the production of MDI fractions containing 2,4′-MDI, and in which the 2,2′-MDI component from the MDA production is largely removed from the isomer mixture. Highly reactive monomeric MDI products can be produced in this way. These MDI products are characterised in their processing by significantly reduced emissions of MDI monomers.
摘要:
The invention relates to an improved process for the production of isocyanates by the reaction of an amine or a mixture of two or more amines with phosgene, the improvement involving the phosgene containing less than about 100 ppm of sulfur in elemental or bound form. The inventive process yields light-colored isocyanates that are suitable for the production of polyurethanes or their precursors (e.g. prepolymers) without the treatment processes heretofore required.
摘要:
The invention relates to an improved process for the production of isocyanates by the reaction of an amine or a mixture of two or more amines with phosgene, the improvement involving the phosgene containing less than about 100 ppm of sulfur in elemental or bound form. The inventive process yields light-colored isocyanates that are suitable for the production of polyurethanes or their precursors (e.g. prepolymers) without the treatment processes heretofore required.
摘要:
The invention provides an improved process for preparing diamines and polyamines from the diphenylmethane series by reacting aniline and formaldehyde in the presence of an acid catalyst, the improvement involving the aniline containing less than about 3 wt. % of diamines and polyamines from the diphenylmethane series, based on the weight of the aniline.