Calcium Looping: On the Positive Influence of SO₂ and the Negative Influence of H₂O on CO₂ Capture by Metamorphosed...

The CO₂ capture performance of sorbents derived from three distinct limestones, including a metamorphosed limestone, is studied under conditions relevant for calcium looping CO₂ capture from power plant flue gas. The combined and individual influence of flue gas H₂O and SO₂ content, the influence of textural changes caused by sequential calcination/carbonation cycles, and the impact of CaSO₄ accumulation on the sorbents' capture performance were examined using bubbling fluidized bed reactor systems. The metamorphosed limestone-derived sorbents exhibit atypical capture behavior: flue gas H₂O negatively influences CO₂ capture performance, while limited sulfation can positively influence CO₂ capture, with space time significantly impacting CO₂ and SO₂ co-capture performance. The morphological characteristics influencing sorbents' capture behavior were examined using imaging and material characterization tools, and a detailed discussion is presented. This insight into the morphology responsible for metamorphosed limestone-derived sorbent's anomalous capture behavior can guide future sorbent selection and design efforts.