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 (r 0 PCH = 0.38 vs 0.34 mmol/min g Co ), 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 Co 0 -Co 2+ 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. • Co/biochar catalysts were investigated for HDO of isoeugenol to propylcyclohexane. • Synergistic Co⁰/Co²⁺ role is demonstrated, with crucial influence of the support. • Co supported on rice husk biochar showed high activity, selectivity, and stability. • DFT with kinetic modeling revealed reaction network and activation energies.