IMPROVED METHOD OF FILTERING PURIFIED CARBOXYLIC ACID Russian patent published in 2014 - IPC C07C51/265 C07C51/47 C07C63/26 

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing pure terephthalic acid. The method includes (a) removing a mother solution from purified terephthalic acid through a filter using a gas, where the gas contains steam; (b) cleaning the gas and (c) recirculating the gas cleaned at step (b) to step (a), wherein concentration of steam is in the range from 50 wt % to 99.9 wt % of the full amount of gas; step (b) is carried out in a gas-liquid contact device. Another method includes (a) oxidising para-xylene to obtain crude terephthalic acid; (b) purifying the crude terephthalic acid to obtain a mother solution which contains pure terephthalic acid; (c) contacting the mother solution with a filter; (d) removing the mother solution from the purified terephthalic acid through the filter using a gas, where the gas contains steam; (e) cleaning the gas and (f) recirculating the gas cleaned at step (e) to step (d), wherein concentration of steam is in the range of 50 wt % to 99.9 wt % of the full amount of gas; step (e) is carried out in a gas-liquid contact device.

EFFECT: improved method.

33 cl, 5 dwg, 2 tbl, 2 ex