Chemical looping combustion of the aqueous phase fraction of bio-oil from biomass pyrolysis

The aqueous fraction of pyrolysis bio-oil, which can account for up to 85 wt.% water, is typically considered a low-value by-product due to its high water content, corrosivity, toxicity, and low heating value. Its effective utilization remains a challenge for the development of sustainable biomass valorization technologies. In this work, the potential of chemical looping combustion (CLC) was evaluated as an alternative route for converting this fraction into energy while enabling inherent CO 2 capture. Several oxygen carriers (OCs) based on Cu, Fe, Ni, and Mn were screened in a fixed-bed reactor at 650 °C using a synthetic model mixture representative of the aqueous bio-oil fraction (acetone, acetic acid, phenol, p-cresol, and 2-butanone). The laboratory-synthesized CuO/Al 2 O 3 powder OC exhibited the best performance, achieving complete oxidation of the mixture to CO 2 and H 2 O without detectable by-products during the combustion phase. Furthermore, the selected OC demonstrated highly stable redox performance and regenerability over multiple cycles at 650 and 750 °C, with the operation at 750 °C effectively minimizing carbon deposition compared to 650 °C. Overall, this low-temperature CLC approach with a CuO/Al 2 O 3 carrier successfully addresses prior challenges of severe carbon deposition and oxygen carrier deactivation, providing a robust pathway for aqueous bio-oil valorization. • Screening of oxygen carriers identified Cu-based materials as the most effective. • CLC is evaluated as a sustainable route for aqueous bio-oil valorization. • CuO/Al 2 O 3 oxygen carrier achieved complete oxidation of the mixture. • CuO/Al 2 O 3 showed highly stable redox performance over multiple cycles. • Operating at 750 °C minimized carbon deposition compared to 650 °C.