Thermal pretreatment of CaO for carbon capture

Thermal pretreatment could help improve the stability of CaO during cycles of CO2 capture. The following content is copied from an open access paper (

“The main idea behind thermal pretreatment is to stabilize sorbent morphology, which aids in maintaining sorbent CO2 carrying activity along cycles. CO2 looping cycles were performed with samples pretreated at different temperatures (800–1,300 °C) for different durations (6–48 h). It can be seen in Figure 5 that the sample treated at 900 °C had ∼20% lower conversion in the first cycle than that of the original sample. However, conversion for the pretreated sample increased and in the third cycle was ∼8% higher than that of the original sample. In subsequent cycles, conversion was typically at least 10% greater than that of the original untreated sorbent. Also, experiments performed with pretreated hydrated samples show significant increase of conversions for the initial 6–7 cycles. This effect we have called self-reactivation. Perhaps the most interesting result is seen for powdered samples (<50 μm). It can be seen that self-reactivation occurred for the entire 30 cycles, and the highest conversion was obtained for the last cycle (49%). This finding was supported by experiments with four Canadian limestones [26]. However, it should be mentioned that there are sorbents that do not show enhanced performance after pretreatment at high temperatures, and La Blanca (Spanish) limestone is one such example [49].”


Figure 5. The effect of sorbent preheating for 24 h on its CO2 carrying capacity in TGA [26]. Kelly Rock, 0.300–0.425 mm; calcination (100% N2, 10 min); carbonation (50% CO2, N2 balance, 30 min); isothermally at 800 °C.”

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