Net carbon reduction from the pyrolysis of corn stover.

Cellulosic biomass, such as corn stover, serves as a promising source to produce biofuels, particularly bioethanol through fermentation. Despite the well-establishment of fermentation, it poses limitations in fully utilising cellulosic constituents due to generation of metabolic byproducts, such as carbon dioxide (CO2). In a pursuit of efficient carbon utilization, this study proposes pyrolytic valorization of corn stover due to its technical benefit in carbon reallocation into three distinct pyrolytic products. Nevertheless, given the energy-intensive nature of pyrolysis, the process-related CO2 emissions remain inevitable carbon loss. To impart sustainability, CO2 was introduced as a reactive medium to the pyrolysis system. Understanding the mechanistic roles of CO2 is a primary aim of this study. CO2 showed a reactivity of interacting with the volatiles derived from corn stover, leading to their conversion into syngas enriched with carbon monoxide (CO). However, the CO production driven by CO2 was notable only above 490 °C. To accelerate the CO2 reactivity, catalytic pyrolysis over a nickel catalyst was performed under controllable variables: catalyst bed temperatures and CO2 composition. The systematic investigation enabled optimization of CO-rich syngas production, showing a 10.6-times increase compared to referenced pyrolysis. To evaluate the environmental benefits, a carbon footprint of the CO-cofed catalytic pyrolysis was calculated theoretically. The proposed pyrolysis platform offers potentials of suppressing 1107.11 g CO2 per kilogram of corn stover consumed. Therefore, these findings highlight the potential of using CO2 in the pyrolytic valorization of corn stover for achieving net carbon reduction.