Effect of Process Conditions on Catalytic Hydrothermal Oxidation of p-Xylene to Terephthalic Acid br

This study investigates the influence of hydrothermal process conditions on the yield of terephthalic acid (TPA). Deionised water was employed as a green reaction medium substitute for acetic acid solvent widely used in the Amoco oxidation process for TPA production. Utilising the unique properties of water at elevated temperature and pressure, TPA was synthesised from p-xylene under subcritical (250 degrees C, 300 degrees C and 350 degrees C) and supercritical (400 degrees C) water conditions in a 10 mL micro-bomb batch reactor. Process bromide (MnBr2) catalyst and water loadings, were varied at a fixed reaction time of 60 minutes. The p-xylene conversion and TPA yield were determined using high-performance liquid chromatography (HPLC). In addition, the presence of chemical functional groups and chemical compositions of the reaction products were examined using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometer (GC-MS), respectively. It was found that an optimum TPA yield of 94.56% was observed at 350 degrees C with hydrogen peroxide, deionised water and manganese bromide catalyst set at 1.5 mL, 2.5 mL, and 2 mL, respectively. Other major reaction products identified were p-tolualdehyde and 1,4-hydroxymethyl benzaldehyde.