| 摘要 |
PURPOSE:To obtain terephthalic acid having high transparency and utilizable directly as a raw material of polyester, by recycling a specific amount of the oxidation exhaust gas continuously to the liquid phase of a reactor for the production of terephthalic acid by SD-process, and reacting the components under increased oxygen partial pressure in the vapor phase. CONSTITUTION:p-Xylene is oxidized with air in liquid acetic acid solvent in the presence of a catalyst containing Co, Mn and Br at 180-230 deg.C keeping the oxygen concentration in the oxidation exhaust gas to 2-8vol%. In the above process, the condensable component of the gas extracted from the reactor is condensed and removed, the residual oxidation exhaust gas is divided into two parts, and one part of the gas, corresponding to 0.3-5pts.vol, preferably 0.5- 3pts.vol. per 1pt.vol. of the other part of the gas discharged from the system, is recycled continuously to the liquid phase of the reactor (preferably at a point under the liquid surface by more than 20% of the depth). The reaction pressure is raised, and the oxidation reaction is carried out keeping the oxygen partial pressure in the vapor phase to 1.3-5 times, especially 1.5-3 times the pressure of the conventional process. Terephthalic acid having high transparency can be produced by this process. |
