Influence of SO2 concentration on carbon capture using NaBr-CaO

“In the actual calcium looping process, the sorbent is often exposed to trace SO2 atmosphere, and the carbonation/sulfation competitive adsorption on the CaO-based sorbent is important to the CO2 capture process. However, up to now, there is a lack of research on carbonation/sulfation competitive adsorption, and rare work reported on the SO2/CO2 competitive adsorption of NaBr modified CaO-based materials. Therefore, in this paper, the SO2 and CO2 competitive sorption on the NaBr modified CaO-based adsorbent will be evaluated by the self-made TGA, and the influence of SO2 concentration in the carbonation and calcination environment on the cyclic CO2 capture capacity of CaO-based adsorbent will be deeply studied.”

“Figure 2(a) showed the effect of different SO2 concentrations on the CO2 capture capacity of the NaBr modified “CaO, AR” in the calcium looping environment (as shown in Table 1, run 2#–4#). Figure 2(b) showed the cumulative SO2 adsorption capacity of the CaO-based sorbents under these different reaction modes. It can be seen that with the progress of the calcium looping process, the cyclic CO2 capture capacity of the CaO-based adsorbent still decreased rapidly; in addition, with the increase of SO2 concentration in the reaction, the cyclic CO2 capture capacity of CaO-based adsorbent decreases more rapidly. Exposed to 0.1 %, 0.2 %, and 0.3 % SO2 atmosphere (run 2#, 3#, and 4#), “CaO, AR” has a similar CO2 capture capacity (0.52g-CO2/g-sorbent) in the first carbonation; but after 10 cycles, the CO2 capture capacity of “CaO, AR” decreased to 0.211 g/g, 0.181 g/g, and 0.131 g/g, respectively. The SO2 concentration has a strong relationship with the attenuation of their cyclic CO2 capture capacity. After 10 cycles, the CO2 capture capacity of the “CaO, AR” under the condition of 0.1 % SO2 (mode 2#) was 1.6 times higher than that under the condition of 0.3 % SO2 (mode 4#). At the same time, with the increase of SO2 concentration, the sulfation conversion of CaO-based sorbent increased gradually. As shown in Figure 2b, after 1 cycle, the cumulative SO2 absorption of “CaO, AR” under runs 2#, 3#, 4# was 0.008 g/g, 0.03 g/g, and 0.05 g/g; moreover, with the progress of the calcium looping process, the sulfation conversion rate of the sorbent in the atmosphere of higher SO2 concentration was also higher. Finally, the cumulative SO2 capture capacity of the “CaO, AR” in these three modes was 0.14 g/g, 0.29 g/g, and 0.32 g/g respectively.”


Figure 2. (a). Effect of SO2 concentration on CO2 capture characteristics in the “NaBr/CaO” over the calcium looping process; (b). Effect of NaBr modification on the cumulative SO2 capture capacity of “CaO, AR”.”

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