Strategic management of harmful chemicals produced from pyrolysis of plastic cup waste using CO₂ as a reaction medium

Disposable plastic cup has been expensively used in our daily life due to its versatility, usability, and affordability. However, the mass increase in plastic cup waste (PCW) becomes detrimental environmental issues because the current plastic disposal process could be a vector for microplastics and hazardous compounds. In this study, an environmentally benign disposal and valorization process of PCW was suggested. In particular, pyrolysis of PCW was performed using a greenhouse (CO₂) as a reaction medium. The thermal degradation of PCW produced hazardous benzene derivatives because PCW was made of polyethylene terephthalate. The harmful aromatic compounds (benzene derivatives) were detoxified by means of syngas production (H₂ and CO) in the presence of a Co catalyst. Effects of CO₂ and Co catalyst resulted in conversion of more than 95 % of toxic chemicals, benzene derivatives, into syngas at 700 ˚C. CO₂ also effectively suppressed a deactivation of Co catalyst because gas phase reactions between CO₂ and benzene derivatives mitigated (hydro)carbon formations that can be deposited on the catalyst surface. Thus, this study proposed that CO₂-assisted catalytic pyrolysis is a promising approach to convert disposable plastic container and CO₂ into value-added products with mitigation of harmful chemical production.