Syngas production through CO2-assisted catalytic pyrolysis of ethylene vinyl acetate (EVA) with a cobalt-based catalyst

Abstract

Ethylene vinyl acetate (EVA) is a representative copolymer widely adopted across various sectors owing to its superior physiochemical properties; however, an environmentally benign protocol for the disposal of EVA waste has not yet been established owing to the various ratios of acetate to polyethylene. Therefore, in this study, we proposed an innovative thermochemical technique for converting EVA waste into energy resources, specifically syngas. CO2 was used to enhance the environmental sustainability of pyrolysis. Thermogravimetric analysis revealed that most of the EVA (approximately 99 wt%) was converted into pyrolytic oil and gases. However, the mechanistic features of CO2 in the pyrolysis of EVA could not be fully elucidated through single- or double-stage pyrolysis owing to the slow kinetics of the homogeneous reaction between CO2 and volatiles. To expedite the reaction kinetics, we used a cobalt (Co)-based catalyst (Co/SiO2). In the presence of Co/SiO2, the concentration of CO produced under CO2 was approximately 30-fold higher than that under N2. Furthermore, the homogeneous reactions resulted in fewer benzene derivatives and polycyclic aromatic hydrocarbons (PAHs) in the pyrolytic oil under CO2 conditions. These experimental findings suggest that CO2 and EVA could serve as valuable feedstocks for the production of energy.