METHOD OF PRODUCING AND PURIFYING ISOPHTHALIC ACID Russian patent published in 2012 - IPC C07C63/24 C07C51/265 C07C51/42 C07C51/43 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing and purifying isophthalic acid, involving step-by-step oxidation of m-substituted alkylbenzenes with atmospheric oxygen in acetic acid in the presence of a Co-Mn-Br catalyst at high temperature and pressure, followed by purification of the formed isophthalic acid via recrystallisation, wherein pure isophthalic acid is obtained via oxidation of m-xylene (or m-cymene) in two steps in narrow ranges of parameters on the steps (1, 2): T, °C - 191-194/194-195, with total concentration of Co and Mn - 800-1200 ppm, ratio Co:Mn=2.1-3.0:1, concentration of [H₂O] in oxidation zones - 3.8-7.0/3.2-6.0 wt %, [O₂] in spent O₂ gas 2-4-5 vol. % and within 30-50 minutes, [m-KBA]=0.015-0.025% colour index ≤18°H is achieved in oxidation products, after which the extracted high-quality isophthalic acid is purified by recrystallising in water at temperature 170-225°C, and if said [m-KBA] and colour index are exceeded in high output conditions by increasing the load of m-xylene, the purification process is combined with hydrogenation of impurities on a composite catalyst consisting of Ru and Pd in weight ratio Ru:Pd=1:0.25-1.5 with total concentration [Ru+Pd]=0.5 wt %, in porous material based on a carbon support, activated carbon or a graphite-like material with total pore volume 0.6-0.8 cm³/g, and hydrogenation is carried out for 36-60 minutes at 170-225 °C.

EFFECT: high efficiency of production and purification, simple process.

2 cl, 1 dwg, 1 tbl, 11 ex