Catalytic wet air oxidation of polyethylene glycol

The catalytic oxidation of aqueous solutions of polyethylene glycol of molecular weight 10000, a synthetic polymer used in a wide range of applications, has been investigated using various metal oxide and noble metal heterogeneous catalysts. Catalysts were in slurry or in pellets, at temperatures from 383 K to 463 K and an oxygen partial pressure of 3 MPa. Additional uncatalysed experiments have been performed, and the results are compared to those of the catalysed runs. Reaction intermediates have been determined using HPLC and gel permeation chromatography as the main analytical techniques, and reaction mechanisms have been proposed. Noble metal catalysts were found to be more effective than metal oxide catalysts for oxidising polyethylene glycol, while with both noble metal and metal oxide catalysts the rate of total oxidation was significantly higher than that of the uncatalysed reaction. However, the use of heterogeneous catalysts was found to be responsible for prolonged induction periods, a phenomenon which did not occur significantly during the uncatalysed runs. A palladium supported on alumina catalyst was further studied with respect to its stability and deactivation.