Recent advances in organic waste pyrolysis and gasification in a CO2 environment to value-added products.

The persistent combustion of fossil fuels has resulted in a widespread greenhouse effect attributable to the continual elevation of carbon dioxide (CO 2) levels in the atmosphere. Recent research indicates that utilizing CO 2 as a pyrolysis gasification medium diminishes CO 2 emissions and concurrently augments the value of the resultant pyrolysis gasification products. This paper reviews recent advancements in the pyrolysis gasification of organic solid wastes under a CO 2 atmosphere. Meanwhile, the mechanisms of CO 2 influence in the pyrolysis and gasification processes were also discussed. In comparison to noble gases, CO 2 exhibits reactivity with char at≥710 °C, resulting in additional mass loss of the sample. In addition, CO 2 was able to increase the specific surface area and stability of biochar and reduce biooil toxicity by lowering the content of cyclic compounds in the biooil, while CO 2 was able to react with GPRs with some volatile products (e.g., light hydrocarbons) to increase biogas yield. Finally, CO 2 also prevents catalyst deactivation by reducing secondary coke formation. We also recommend directing future attention toward utilizing unpurified CO 2 in pyrolysis and gasification. This review aims to expand the utilization of CO 2 and advocate for applying pyrolysis gasification products. [Display omitted] • An overview of recent studies on pyrolysis gasification in CO 2 atmosphere. • The effect of CO 2 on the pyrolysis behavior as well as on the catalyst is illustrated. • The mechanism of the effect of CO 2 on pyrolysis products is described in detail. • In the future, CO 2 and waste heat from industrial flue gases should be utilized directly. [ABSTRACT FROM AUTHOR]