Carbon emission mitigation from the CO2-cofed pyrolysis of invasive biomass: A case study on kudzu (Pueraria montana)

• Carbon dioxide was employed in pyrolysis of kudzu vine, an invasive plant. • Carbon dioxide partially oxidized vine-derived volatiles into carbon monoxide. • Syngas, enriched with carbon monoxide, was produced under diverse parameters. • Carbon emission reduction was maximized at a 50 % volumetric input of carbon dioxide. • Net carbon reduction of 2.96 g carbon dioxide per gram of kudzu vine was achieved. Pyrolysis is a thermochemical strategy for converting lignocellulosic biomass into biofuels; however, the process is inherently energy-intensive, limiting its environmental benefits. To impart a sustainability during the pyrolysis, this study proposes an incorporation of carbon dioxide as a cofeeding agent for the valorization of kudzu vine, an invasive species. The use of carbon dioxide provides opportunities to enhance carbon availability in the pyrolysis system through its partial oxidative function, while mitigating process-related carbon emissions. Above 490 ˚C, the introduction of carbon dioxide altered the syngas composition by enhancing production of carbon monoxide, indicating its homogeneous interaction with pyrolytic volatiles derived from kudzu vine. To further promote reactivity of carbon dioxide, a nickel-based catalytic bed was incorporated, with system performance evaluated at 500, 600, and 700 ˚C. This catalytic configuration increased the yield of carbon monoxide via carbon dioxide reduction. Optimization at 700 ˚C with varying concentrations of carbon dioxide revealed a convergence in the net carbon emissions at a 50 % volumetric input of CO 2 , corresponding to a net reduction of 2.96 g carbon dioxide per gram of kudzu vine. These findings advance the development of carbon-negative pyrolysis systems and highlight the potential of carbon dioxide as a reactive agent for sustainable biofuel production.