318results about "Isocyanic acid derivatives purification/separation" patented technology

Process for the purification of toluenediisocyanate from a crude distillation feed comprising toluenediisocyanate, an organic solvent and less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into at least four product fractions P1-P4. P1 is a phosgene enriched low-boiler product, P2 is a solvent-enriched product, P3 is a high boiler enriched bottoms and P4 is a toluenediisocyanate product stream.

A mixture of isomeric diisocyanatodiphenylmethanes composed of at least 2,2′-diisocyanato-diphenylmethane, 2,4′-diisocyanatodiphenylmethane and 4,4′-diisocyanatodiphenyl-methane is distilled in at least one stage and a divided-wall column is used in at least one distillation stage.

Process for the purification of toluenediisocyanate from a crude distillation feed which includes toluenediisocyanate, an organic solvent and less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into at least four product fractions P1–P4. P1 is a phosgene enriched low-boiler product,P2 is a solvent-enriched product,P3 is a high boiler enriched bottoms andP4 is a toluenediisocyanate product stream.

Isocyanates are produced by reacting an organic amine with phosgene in process which includes at least three stages. The first stage is carried out in a dynamic mixer. The second stage is carried out in at least one reactor. The third stage is carried out in at least one material separating apparatus. The pressure in the reactor of the second stage must be greater than or equal to the pressure in the dynamic mixer. The pressure in the third stage material separating apparatus must be lower than the pressure in the second stage reactor.

The invention relates to a refining and reclaiming technology of a tail gas absorption solvent in the production of toluene diisocyanate (TDI). The solvent containing little phosgene, toluene diisocyanate and di-Et-1,3-benzenedicarboxylate (DEIP) performs two-stage refinement in an atmospheric refining tower and a vacuum refining tower, and a falling-film evaporator and a storage tank are arranged between the two towers. The overhead non-condensable gas phase of the atmospheric refining tower is returned to a phosgene absorption tower to recycle phosgene, the refined solvent is drawn from theside of the atmospheric refining tower, the temperature of the tower bottom is controlled to be 3-8 DEG C higher than the boiling point of the solvent, the discharged material of the tower bottom enters the falling-film evaporator, the evaporating temperature is 20-30 DEG C higher than the boiling point of the solvent, the unevaporated material enters the storage tank for storage, the material inthe storage tank performs batch vacuum rectification under the absolute pressure of 0.1-0.25bar, and the unevaporated residual material enters the residue evaporator of a TDI device to recycle TDI and DEIP. By using the solvent refining technology provided by the invention, the useful components in the solvent can be completely recycled, and the technology has the advantages of simple and stable operation and lower cost and energy consumption.

An isocyanate is produced by reacting a primary amine with phosgene in the gas phase above the boiling point of the amine over an average contact time of 0.05 to 15 seconds under adiabatic conditions.

Isocyanates are produced by reaction of primary amines with phosgene in the gas phase. In this process, the reaction is terminated by guiding the reaction mixture from the reaction chamber through a cooling stretch into which liquids are injected. Direct cooling takes place in the cooling stretch in one stage in two or more cooling zones connected in series.

Isocyanates are produced by a) reacting at least one amine with phosgene, optionally in the presence of a solvent to produce the corresponding isocyanate and a stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances is obtained, b) separating the stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances in an at least two-stage sequence of absorption steps that includes (1) at least one isothermal absorption step and (2) at least one adiabatic absorption step, to obtain (i) a hydrogen chloride stream containing phosgene in concentrations of at most 0.5 wt. % (based on the weight of the hydrogen chloride stream) and (ii) a liquid phosgene stream, and c) recycling the liquid phosgene stream (ii) to the reaction of amine with phosgene.

The invention relates to a light color modified isocyanate mixture and a preparation method thereof. The method comprises the following steps: (a) carrying out reaction on isocyanate groups of the rawmaterial isocyanate in the presence of phosphorus-heterocycle catalysts, and finally obtaining a modified isocyanate reaction solution containing carbodiimide and / or uretonimine derivatives; and (b)adding a terminating agent compounded from halogenated silane organic matters and sulfonic anhydrides into the reaction solution obtained in the step a so as to terminate the carbodiimide reaction. The modified isocyanate prepared by the method has the characteristics of normal-temperature liquid and normal temperature and high temperature storage stability and low color number.

The invention discloses a method for recovering heat integrated solvent in the continuous production of toluene di-isocyanate, comprising the following steps: respectively importing materials to be distilled, which contains the toluene di-isocyanate and an inert organic solvent, to a first solvent eliminating tower with higher operation pressure and a second solvent eliminating tower with lower operation pressure to carry out distillation; leading steam from the top of the first solvent eliminating tower into a first condenser and leading part of tower bottom liquid in the second solvent eliminating tower into the first condenser to carry out heat transferring; and leading part of the tower bottom liquid from the first solvent eliminating tower and the second solvent eliminating tower intoa third solvent eliminating tower to carry out distillation. The method can obviously reduce the energy consumption in the production of the toluene di-isocyanate, thereby reducing the production cost of a unit toluene di-isocyanate product.

Isocyanates are produced by reaction of primary amines with phosgene in the gas phase. In this process, the reaction is terminated by guiding the reaction mixture from the reaction chamber through a cooling stretch into which liquids are injected. Direct cooling takes place in the cooling stretch in one stage in two or more cooling zones connected in series.

The present disclosure relates, according to some embodiments, to apparatus, systems, and / or methods for fractionating a feed mixture comprising, for example, one or more isocyanates, light components, solvents and / or heavier components. In some embodiments, fractionating an isocyanate feed mixture may comprise distilling the feed mixture in a non-adiabatic fractionating apparatus comprising a prefractionating section and / or column and a main section and / or column, which comprises a rectification section, a side section, and a stripping section. For example, isocyanates may be separated from light component(s), solvent(s) and / or heavier component(s). A fractionating apparatus may be configured and arranged, in some embodiments, as a dividing wall column. According to some embodiments of the disclosure, apparatus, systems, and / or methods may be energy efficient and / or may have a broad operating range.

Isocyanates are produced by reacting an organic amine with phosgene in process which includes at least three stages. The first stage is carried out in a dynamic mixer. The second stage is carried out in at least one reactor. The third stage is carried out in at least one material separating apparatus. The pressure in the reactor of the second stage must be greater than or equal to the pressure in the dynamic mixer. The pressure in the third stage material separating apparatus must be lower than the pressure in the second stage reactor.