An Eco-friendly Cleaning Strategy for Preparing Synfuel from Biomass via Carbonization Technology: Directed Conversion and Synergistic Decoupling Combustion

• Prepare carbon-based synfuel using biomass and low-grade coal. • Realized the substitution of biomass for high-grade coking coal. • The sinter ore catalyst enhances the co-carbonization effect. • Promote dehydrogenation and condensation of aromatic rings. • Enhance ignition performance and combustion stability. To address the high carbon emissions in the steel industry, this study uses sawdust and low-rank bituminous coal as raw materials, sintered ore powder as a catalyst, and employed characterization methods such as thermogravimetric analysis and X-ray diffraction. Through synergistic co-carbonization technology, the optimal carbonization conditions for preparing carbon-based synfuel were investigated, and the combustion kinetics mechanism was elucidated. The results revealed that a carbon-based synfuel with a calorific value of 28.6 MJ·kg -1 , a solid yield of 51.6%, and a bulk density of 581 kg·m -3 was successfully prepared under the following conditions: carbonization temperature of 800 °C for 60 min, sawdust/low-rank bituminous coal ratio of 4/6, and addition of 8 wt.% sinter powder. The core scientific contribution lies in elucidating the synergistic catalytic mechanism of iron and calcium oxides in sinter ore, which promotes oxygen vacancy formation. These vacancies regulate carbon structure evolution by enhancing the cleavage of oxygen-containing functional groups and the ordering of the carbon lattice, thereby reducing the combustion activation energy to 11.6 KJ·mol -1 and achieving a comprehensive combustion index of 2.45 × 105 S -1 ·°C -3 . Beyond the specific sintering application, this study provides a universally applicable strategy for upgrading low-grade feedstocks. The mechanistic insights into oxygen-vacancy-mediated catalysis offer a theoretical foundation for designing tailored carbon-based fuels for broader applications, including power generation, cement production, and industrial boilers. This work presents a low-cost, scalable pathway for biomass valorization and fossil fuel substitution, contributing to the circular economy and low-carbon transition across energy-intensive industries.