Rice straw-derived nitrogen-doped activated carbon for selective aromatization and CH4-enriched syngas production during two-stage catalytic co-pyrolysis of rice straw and polyethylene
The efficient valorization of agricultural residues and plastic waste into high-value fuels and chemicals remains a major challenge because of the oxygen-rich nature of biomass-derived vapors and the limited selectivity of conventional catalysts. In this study, nitrogen-doped activated carbon (xNAC) catalysts were synthesized from rice straw (RS) through a two-step impregnation–carbonization strategy using urea as the nitrogen source and subsequently applied to the ex-situ catalytic co-pyrolysis of RS and polyethylene (PE) in a two-stage fixed-bed reactor. The influences of feedstock blending ratio, nitrogen doping level, and catalytic reforming temperature on product distribution and composition were systematically investigated. Comprehensive characterization demonstrated that moderate nitrogen doping produced a hierarchical porous carbon with a high specific surface area (1005.28 m2 g−1) and abundant pyridinic and pyrrolic nitrogen functionalities, which significantly enhanced catalytic upgrading of pyrolysis vapors. Systematic evaluation of reaction parameters revealed optimal conditions at a feedstock ratio of RS:PE = 1:2, using the 0.8NAC catalyst at a catalytic reforming temperature of 700 °C. Under these conditions, the catalyst achieved efficient deoxygenation and selective aromatization, yielding a bio-oil containing 92.69% aromatic hydrocarbons. Specifically at the optimal 700 °C, it enriched monocyclic aromatic hydrocarbons (MAHs, notably toluene) and restricted the over-condensation into polycyclic aromatic hydrocarbons (PAHs), alongside the simultaneous production of CH4-rich syngas (159.94 mL g−1). Mechanistic analysis indicates that the superior catalytic performance originates from the synergistic effects of hydrogen transfer between biomass- and plastic-derived radicals, Diels–Alder cycloaddition, pore-confinement-induced shape selectivity, and nitrogen-mediated activation of C–O bond cleavage, deoxygenation, aromatization, and controlled cracking reactions. This work demonstrates a sustainable waste-to-waste strategy that integrates catalyst preparation and catalytic upgrading using RS as both catalyst precursor and feedstock, providing an effective approach for the selective production of aromatic-rich bio-oil and CH4-rich syngas from biomass–plastic co-pyrolysis. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Библиографическая ссылка Jin, Ruiyang, Zhou, Yihua, Kouotou, Mohamar Junior Njindi, Tahir, Mudassir Hussain, Zhu, Nanfeng, Zhang, Yimeng, Kozlov A.N., Penzik M.V., Zhang, Shu Rice straw-derived nitrogen-doped activated carbon for selective aromatization and CH4-enriched syngas production during two-stage catalytic co-pyrolysis of rice straw and polyethylene // Journal of Analytical and Applied Pyrolysis. Vol.200. ID:108140. 2026. DOI: 10.1016/j.jaap.2026.108140
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