Syngas production through CO2-mediated pyrolysis of polyoxymethylene

Plastics have become an integral part of our daily lives owing to their exceptional physicochemical properties, such as durability, low density, and cost-effectiveness, compared to traditional materials. However, the escalating production of plastics has resulted in a proportional increase in waste generation. This paper proposes environmentally benign valorization/disposal methods for plastic waste, with a particular focus on adopting a pyrolysis process that utilizes CO2 as a strategic reaction medium. As a case study, polyoxymethylene (POM), a widely used engineering plastic, was valorized through CO2-mediated pyrolysis. This study experimentally demonstrates the mechanistic effectiveness of CO2 in expediting the reaction kinetics of the thermal decomposition, specifically dehydrogenation and deoxygenation, of volatile matter derived from POM. The results revealed that employing CO2 as a reactant in the two-stage pyrolysis at 500 °C produced 30.47 mmol more syngas than under inert conditions. In conclusion, the strategic utilization of a two-stage pyrolysis process at 500 °C with CO2 as the reactant has emerged as an effective approach to the valorization of POM. This study contributes to developing sustainable methods for managing plastic waste by addressing environmental concerns and the need for efficient material recovery.