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 a pplications, 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 o f 3 MPa. Additional uncatalysed experiments have been performed, and t he results are compared to those of the catalysed runs. Reaction inter mediates have been determined using HPLC and gel permeation chromatogr aphy as the main analytical techniques, and reaction mechanisms have b een proposed. Noble metal catalysts were found to be more effective th an metal oxide catalysts for oxidising polyethylene glycol, while with both noble metal and metal oxide catalysts the rate of total oxidatio n was significantly higher than that of the uncatalysed reaction. Howe ver, the use of heterogeneous catalysts was found to be responsible fo r prolonged induction periods, a phenomenon which did not occur signif icantly during the uncatalysed runs. A palladium supported on alumina catalyst was further studied with respect to its stability and deactiv ation.