Preparation of Terephthalic acid (TPA) and Dioctyl terephthalate (DOTP) by Anthracite's Alkali Oxygen Oxidation

摘要

TPA was synthesized by a two step reaction. Firstly, water-soluble coal acids (CA) was obtained by oxygen-oxidation at 260°C in all aqueous solution of potassium hydroxide, and then crud TPA was got by isomerization of the CA with the existence of CdCO_3 catalyst and CO_2 pressure. The optimum reaction conditions to get crude TPA were 4% amount of CdCO_3 catalyst, and reacted at 420°C with initial 3.0MPa CO_2 pressure. Pure TPA was obtained by a separation step and the yield of pure TPA is 37.16% (based on CA). Furthermore, DOTP was synthesized by the refined TPA and isooctanol. The influence of mole ratio of TPA and isooctanol, amount of catalyst and reaction time on the final yield of DOTP were discussed. The purity of TPA was detected by HPLC and DOTP was detected by FT-IR, ~1H-NMR to get confirmatory results.