PLANT AND METHOD FOR PRODUCING A PURIFIED ISOMERIC MONOMER SUCH AS 4,4'-METHYLENEDIPHENYLDIISOCYANATE FROM A CRUDE MIXTURE Russian patent published in 2023 - IPC C07C263/20 C07C265/14 B01D1/22 B01D3/26 B01D5/00 B01D9/02 

FIELD: chemical industry.

SUBSTANCE: invention relates to a plant for obtaining purified 4.4'-methylene diphenyl diisocyanate from a mixture of various isomeric methylene diphenyl diisocyanate monomers. The plant contains a distillation device that contains a) a distillation column including a structured packing, b) a source for a mixture of various isomeric methylene diphenyl diisocyanate monomers, c) an evaporator, d) a head vapour condenser, e) a head vacuum system, and f) a flow-controlled reflux system. The head vapour condenser has a shell-and-tube configuration and is designed in such a way as to directly supercool the condensate to a temperature below 47°C. The flow controlled reflux system comprises a heater which is configured to reheat the partial condensate stream that forms in the head vapour condenser to 190°C. The invention also relates to a process for the preparation of purified 4,4'-methylene diphenyl diisocyanate from a crude mixture containing various isomeric methylene diphenyl diisocyanate monomers, as well as the corresponding dimers, oligomers and polymers. The method is carried out in the above installation by feeding a mixture of different isomeric methylene diphenyl diisocyanate monomers to the evaporator. The invention also relates to a purified composition 4,4'-methylene diphenyl diisocyanate, obtained as a condensed head product of the distillation column of the plant. EFFECT: proposed installation and method make it possible to obtain purified 4.4'-methylene diphenyl diisocyanate from a mixture of various isomeric methylene diphenyl diisocyanate monomers and provide a reduced dimer concentration in the purified product.

15 cl, 3 dwg