Ash Interaction with Two Cu-Based Magnetic Oxygen Carriers during Biomass Combustion by the Chemical Looping with Oxygen Uncoupling Process.

Abstract

Chemical-looping combustion (CLC) stands out as a promising method for carbon capture and storage for the purpose of mitigating climate change. The process involves the conversion of fuel facilitated by an oxygen carrier, with the resulting CO₂ inherently separated from other air components. Notably, when applied to biomass combustion this process offers a pathway to achieving negative CO₂ emissions. However, a significant challenge for CLC, particularly in its application to biomass, is the management of interactions between ash and oxygen carriers. Biomass-derived ashes typically contain substantial quantities of reactive ash-forming substances, such as alkaline and alkali earth elements. These interactions can impact the performance and longevity of the oxygen carrier, necessitating careful consideration and mitigation strategies in CLC systems utilizing biomass feedstocks. This study examined the interaction between biomass ash components and two recently developed oxygen carriers, Cu30MnFekao7.5 and Cu30MnFe, during combustion in a 1.5 kW_th continuous unit. Both oxygen carriers achieved 100% combustion efficiency and a CO₂ capture efficiency of 95% at 900 °C. Although the copper in both oxygen carriers did not exhibit any noticeable interaction with ash components, the accumulative presence of potassium and magnesium in Cu30MnFekao7.5 was identified by inductively coupled plasma and scanning electron microscopy with energy dispersive X-ray analysis, indicating an increase in the amount of both elements in the particles after combustion operation. No problems of agglomeration or fluidization were observed in any of the experiments.