| Summary: | The use of wastes of marble powder (WMP) and dolomite as sorbents for CO<sub>2</sub> capture is extremely promising to make the Ca-looping (CaL) process a more sustainable and eco-friendly technology. For the downstream utilization of CO<sub>2</sub>, it is more realistic to produce a concentrated CO<sub>2</sub> stream in the calcination step of the CaL process, so more severe conditions are required in the calciner, such as an atmosphere with high concentration of CO<sub>2</sub> (>70%), which implies higher calcination temperatures (>900 °C). In this work, experimental CaL tests were carried out in a fixed bed reactor using natural CaO-based sorbent precursors, such as WMP, dolomite and their blend, under mild (800 °C, N<sub>2</sub>) and realistic (930 °C, 80% CO<sub>2</sub>) calcination conditions, and the sorbents CO<sub>2</sub> carrying capacity along the cycles was compared. A blend of WMP with dolomite was tested as an approach to improve the CO<sub>2</sub> carrying capacity of WMP. As regards the realistic calcination under high CO<sub>2</sub> concentration at high temperature, there is a strong synergetic effect of inert MgO grains of calcined dolomite in the blended WMP + dolomite sorbent that leads to an improved stability along the cycles when compared with WMP used separately. Hence, it is a promising approach to tailor cheap waste-based blended sorbents with improved carrying capacity and stability along the cycles under realistic calcination conditions.
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