Synthesis of metal and nitrogen co-doped activated carbon catalysts for the co-production of monocyclic aromatics and hydrogen-rich gas from the pyrolysis of biomass and plastic

In this study, various metals, including Fe, Co, Ni, and Zn, were co-doped with non-metallic nitrogen into activated carbon (AC) catalysts through a co-impregnation and carbonization process to enhance catalytic performance. These co-doped AC catalysts were employed for catalytic co-pyrolysis of corn stover (CS) and high density polyethylene (HDPE) to produce aromatics and hydrogen using a fixed bed reactor. The synergistic effect between metals and nitrogen significantly enhanced the specific surface area and microporosity of the AC catalysts, while the presence of multivalent metal ions and N-containing functional groups provided abundant active sites. The 10Fe/N-AC catalyst exhibited the highest content of monocyclic aromatic hydrocarbons (MAHs), reaching 60.3 %. Furthermore, the introduction of nitrogen altered the electron transfer properties of Fe, facilitating the reaction between alkyl radicals and the benzene ring, thereby improving the selectivity toward alkylbenzenes. The increased microporous structure of the 10Fe/N-AC catalyst also effectively suppressed the polymerization reactions of MAHs, resulting in the lowest content of polycyclic aromatic hydrocarbons at 19.5 %. Additionally, the 10Ni/N-AC catalyst demonstrated impressive catalytic performance for hydrogen release, achieving a content of 56.2 %. This study presents a promising strategy for enhancing the catalytic performance of AC catalyst in the effective utilization of organic solid wastes.