Isoeugenol hydrodeoxygenation over sustainable biochar-supported cobalt catalysts: Synergistic Co⁰/Co²⁺ sites and mechanistic insights

This work demonstrates the potential of low-cost cobalt catalysts supported on activated biochars from biomass on the hydrodeoxygenation of isoeugenol, bio-oil model compound for the production of sustainable aviation fuels. Co/biochar catalysts were obtained by pyrolysis and steam activation of rice husk, leather waste, and their mixture, followed by metal impregnation, calcination, and reduction. Compared to Co/AC, (commercial active carbon), Co/A-RH, (rice husk biochar), exhibited competitive isoeugenol conversion to propylcyclohexane (PCH) at 300 °C, 30 bar, 4 h, with a higher initial rate (r0PCH = 0.38 vs 0.34 mmol/min gCo), but lower PCH yield (55 % vs 75 %), due to hydrocracking. By kinetic modeling, the activation energy for PCH formation was determined to be 151 kJ/mol. Comprehensive characterization revealed that Co0-Co2+ synergy enhances HDO performance. DFT calculations provided mechanistic insight into the HDO pathways, which were consistent with the experimentally derived reaction network, and kinetic model.