Upcycling Polyoxymethylene via H2O2-mediated Selective Oxidation.

Abstract

The increasing challenge of plastic pollution, coupled with the depletion of fossil resources, necessitates innovative solutions for the sustainable management of end-of-life plastics. This issue is particularly pressing for polyoxymethylene (POM), a widely used engineering thermoplastic known for its exceptional mechanical properties and durability, which degrades slowly and releases harmful formaldehyde (HCHO). In this study, we present a straightforward method to convert POM waste into formic acid (FA) using hydrogen peroxide (H2O2) as the oxidant. While H2O2 is recognized as a selective and mild oxidation agent, its potential for upcycling plastics into valuable chemicals has been largely uncharted. Our approach utilizes microporous aluminosilicate zeolite H-Beta, known for its Brønsted acidity, to effectively catalyze both the depolymerization of POM into HCHO and its subsequent oxidation to FA. A significant aspect of this method is the incorporation of 1,1,1,3,3,3-hexafluoroisopropanol, which enhances depolymerization through strong hydrogen bonding interactions. This catalytic system efficiently transforms a variety of post-consumer POM waste into FA while also facilitating the Baeyer-Villiger-type oxidation of various carbonyl compounds, achieving high yields in both processes. Overall, these findings advance the conversion of plastic waste into value-added chemicals via H2O2-mediated reactions, enhancing sustainable waste management and supporting circular economy principles.