Development and Modeling of a Novel Spray Reactor for p-Xylene Oxidation to Terephthalic Acid

A novel spray reactor for p-xylene oxidation to terephthalic acid (TPA) will be presented. In this concept, the reaction mixture of p-xylene, dissolved catalyst (Co-Mn-Br mixture) and solvent (acetic acid) is sprayed as fine droplets into an excess of oxygen-containing gas environment. It is shown that compared to the conventional process in which air is dispersed into the liquid phase in a stirred reactor, the spray process can alleviate oxygen starvation in the reaction phase resulting in improved selectivity and purity of the TPA product. A collateral advantage of the spray process is the reduction in acetic acid burning which in turn reduces CO2 emissions. The spray reactor performance (with respect to p-xylene conversion, TPA yield and purity) was investigated as a function of operating variables such as spray rate, pressure, temperature and feed composition. A spray reactor model which accounts for the inter- and intra-phase gas/droplet mass transfer processes will be presented to provide insights into the open-loop stability and inherent safety aspects of reactor operation.