A study on the m-xylene oxidation to isophthalic acid under the catalysis of bromine-free homogeneous catalytic system

Isophthalic acid (IPA) is usually produced by the Co–Mn–Br catalyst system. In this study, a bromine-free catalyst system consisting of H3PW12O40/Co(OAc)2/Mn(OAc)2 has been put forward to oxidizing m-xylene (MX) to IPA. The experimental results proves that the homogeneous H3PW12O40/Co(OAc)2/Mn(OAc)2 catalytic system is able to catalyze the oxidation of MX to IPA. The optimal phosphotungstic acid concentration is 0.52 wt%. The optimum Co(II) concentration for IPA production is between 0.044% and 0.088 wt%. The best Mn/Co ratio is found to be 2.46. Temperature has a strong effect on the reaction rates. Oxygen partial pressure influences on the IPA yield greatly. The kinetic parameters such as activation energies, reaction orders have been estimated.

► A bromine-free catalyst system consisting of H3PW12O40/Co(OAc)2/Mn(OAc)2 has been put forward to oxidizing m-xylene(MX) to isophthalic acid (IPA).
► The optimal catalytic system for MX oxidation to IPA has been determined to be: H3PW12O40 = 0.52%(wt), Co(II) = 0.044%–0.088%(wt), Mn/Co(wt) = 2.46.
► Higher temperature and greater oxygen partial pressure benefit to the production of IPA.
► Kinetic models have been proposed to describe the reaction rate in this catalytic reaction system. The kinetic parameters for this catalytic reaction system such as activation energies, reaction orders have been estimated.