METHOD FOR OBTAINING TEREPHTHALIC ACID FROM SPENT POLYETHYLENE TEREPHTHALATE Russian patent published in 2023 - IPC C08J11/12 C08J11/14 C08L67/02 

FIELD: chemical industry.

SUBSTANCE: invention relates to a method for producing terephthalic acid from waste polyethylene terephthalate by depolymerization with microwave heating and alkaline hydrolysis of the reaction mixture and its subsequent purification. The depolymerization is carried out continuously in two stages in two reactors connected in series, adapted to release the gas phase, from which the second reactor is adapted to operate at reduced pressure to remove monoethylene glycol. The mixture of depolymerization reaction products is mixed with water, the solid phase is separated from the resulting mixture, the resulting solution is extracted with a water-immiscible organic solvent, and after phase separation, the dissolved impurities are removed from the aqueous phase by contact with the sorbent, which is then separated. Terephthalic acid is precipitated from the solution by acidifying it and then separated from the resulting suspension.

EFFECT: technical result of the invention is the creation of a method for producing high purity terephthalic acid from waste polyethylene terephthalate.

4 cl, 4 dwg