Promotional effect of CO2 on low-carbon syngas production from corncob pyrolysis

초록

The demand for crops to ensure food security has led to the substantial generation of crop residues. Nevertheless, conventional management of crop residues through composting and incineration raises environmental concerns, such as air pollutant emission. To address these concerns, this study explored pyrolysis of corncob, and corncob was selected as a widely available crop residue. CO2 was employed as a reactant to modify the pyrolysis mechanisms of corncob. The use of CO2 enhanced syngas production, particularly CO, through the homogeneous interaction (HI) involving CO2 and corncob-derived thermolysates. The oxidative functional role of CO2 promoted the oxidation of thermolysates, with a simultaneous reduction of CO2 into CO. The use of a Ni/Al2O3 catalyst with thermal energy at 700 ℃ promoted the oxidative functional role of CO2, thereby further improving syngas production while using CO2 as oxidative agent. Varying the CO2 loading enabled to control the H2/CO molar ratio by proportionally enhancing CO2-involved HI. Sustainability assessment revealed that CO2-mediated catalytic pyrolysis of corncob yielded 6.10 times more energy as syngas than conventional pyrolysis, while achieving net-negative CO2 emissions, thereby resulting in the production of H2 and CO as low-carbon syngas. Thus, CO2-mediated catalytic pyrolysis of corncob showed a potential to produce sufficient energy to operate the corn industry while offsetting its CO2 emissions. These findings suggest that CO2-mediated catalytic pyrolysis serves as a pathway for valorizing crop residues into low-carbon syngas while simultaneously reducing the CO2 emissions.

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