Chemical looping oxygen uncoupling of biochar using CuO: Influence of oxygen carrier on combustion efficiency

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Despite the consensus on the urgent need to mitigate climate change by reducing CO2 emissions, technological advancements lag the escalating levels of CO 2 . This study investigates the impact of process conditions and oxygen carrier quality on the chemical looping oxygen uncoupling (CLOU) of biochar with CuO as a promising bioenergy production with CO 2 capture and storage (BECCS) approach. This work offers new insights into the role of CuO synthesis method and material source on biochar combustion efficiency in a CLOU framework, comparing both commercial and in-house formulations. Combustion efficiency increases from 67.9 vol% at 750 °C to 98.2 vol% at 900 °C. The stoichiometric ratio also influenced performance, improving from 71.2 vol% at a ratio of 1.0 to 95.7 vol% at 1.5. Higher-quality CuO samples, such as CuO (Honeywell), demonstrated superior performance, achieving 98.3 vol% efficiency compared to 71.2 vol% for CuO (Inoxia) at 850 °C. CuO (Honeywell) also exhibited greater stability across multiple redox cycles, maintaining 99.0 vol% capacity after six cycles, while CuO (Inoxia) suffered a significant decline to 84 vol% due to sintering and agglomeration. Lab-prepared Cu80Al20-WI displayed stable performance, retaining 97.1 vol% after six cycles, outperforming Cu80Al20-CP, which degraded to 83.9 vol%. This performance was mainly attributed to gas diffusional effect and larger availability of active sites in Cu80Al20-WI for oxygen in reduction/oxidation CLC processes. These results highlight the importance of optimising both process conditions and oxygen carrier quality for efficient CLOU applciaiton.