Effect of Different Activation Processes on CaO/Fly Ash Mixture for CO2 Capture

CO2 capture at high temperature through calcium looping is a capable technology for the implementation of carbon capture and storage. The major drawback of this process is the rapid deactivation of calcium-based sorbent due to sintering and attrition. To reduce these drawbacks, an environmentally friendly and low-cost approach is highly appreciated by researchers. Efforts were made to introduce a cost-effective and eco-friendly method to reduce sintering and enhance capacity by adding fly ash from coal-fired plants, into Ca-based sorbents with acetic acid through sonochemical and ball milling methods. Four different methods of mixing were used, i.e., dry, wet, sonochemical, and ball milling methods. The sorbents were characterized by SEM-EDS, XRD, TGA, and XRF. Hydration under acidic conditions with Ca-based sorbent using fly ash showed improved capacity and stability rather than under basic conditions. The sonochemical method achieved the highest CaO conversion of 100% in the first two cycles followed by the ball milling method with 99.8% also maintaining stability through the cycles as compared to other methods. The ball milling method achieved higher improvement to not only proper mixing of fly ash and CaO but also a reduction in sizes improved conversion and stability, and thus it can be considered as a green technology for scaled-up CO2 capture.