Thermal oxidation of polypropylene catalyzed by manganese oxide aerogel in oxygen-enriched supercritical carbon dioxide

A new approach to the thermal oxidation of polypropylene in oxygen-enriched supercritical carbon dioxide is presented. Several parameters are revealed to affect the oxidation process, namely, the presence of supercritical carbon dioxide, the presence of Mn2O3 nanoparticles and oxygen to polypropylene mass ratio. It is demonstrated that the use of carbon dioxide enhances the oxidative process at lower oxygen content. Mn2O3 nanoparticles both increase the rate of the oxidation process and influence the product distribution. Gas chromatography-mass spectrometry reveals that acetone, acetic acid and formic acid are among the main products of the oxidation process. Furthermore, the obtained results show that, at a higher oxygen content, the use of manganese oxide aerogel as a catalyst promotes the selective oxidation of polypropylene, with acetic acid being the main liquid product of the process. (C) 2019 Elsevier B.V. All rights reserved.