In this study, we emphasize the recent progress in the pyrolysis of waste feedstock in the presence of carbon dioxide (CO2). CO2-assisted pyrolysis is compared to typical pyrolysis (i.e., pyrolysis under inert environment, such as nitrogen). It has been shown that CO2 plays a crucial role in increasing the yield of combustible permanent gas (e.g., carbon monoxide) while decreasing tar yield. CO2-assisted pyrolysis is also an attractive technique to treat waste (Organic waste and bio-waste etc.) because CO2 enhances the thermal cracking of volatile species, thereby suppressing the formation of harmful chemical compounds, such as benzene derivatives and polycyclic aromatic hydrocarbons. In addition to highlighting the recent achievements in the CO2-assisted pyrolysis processes, we discuss the points that should be considered for future research.
Also, in this study, carbon dioxide (CO2) were employed to thermally dispose real food waste in the presence of a catalyst. The catalyst and CO2 enhanced the generation of non-condensable gases and hindered the generation of condensable compounds, while they had no effect on the amount of solid residue after the thermal treatment of food waste. In addition, condensable cyclic compounds were reduced when the catalyst and/or CO2 were used for the thermal disposal process. The enhancement of non-condensable gas production and the reduction of cyclic compound formation were maximized when both the Pt catalyst and CO2 applied to the thermal disposal of food waste at the same time. For example, approximately 67.3% less cyclic compounds including benzene derivatives were generated from the thermal treatment of food waste at 700 °C with the catalyst under CO2 atmosphere than from the non-catalytic thermal treatment of food waste under no CO2 condition. This study would suggest that a CO2-assisted catalytic thermal process is a more environmentally benign disposal method for food waste.
