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Direct CO2 Uptake Performance of Mn-Modified Ca(OH)2 in Repeated Carbonation-Calcination-Hydration Cycles: Experiment and Density Functional Theory Study
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DOI：10.1002/adsu.202500258.png)
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Abstract
En 中文
Ca(OH)(2) can be used in CO2 uptake from the flue gas in fossil-fired power plants. Compared with indirect method where Ca(OH)(2) is first converted into CaO and then uptakes CO2, direct CO2 uptake by Ca(OH)(2) occurs at lower temperature, leading to slighter sintering. However, the direct CO2 uptake capacity of Ca(OH)(2) should be further enhanced. In this study, Ca(OH)(2) is doped with Mn to improve its direct CO2 uptake capacity in carbonation-calcination-hydration cycles. The cyclic tests are conducted in a triple fixed-bed reactor. The mechanism of CO2 adsorbed on Mn-modified Ca(OH)(2) is determined by density functional theory calculations. In the first cycle, Mn-modified sorbents acquire highest carbonation conversion at 400 degrees C, which is 40 degrees C lower than Ca(OH)(2). The modified Ca(OH)(2) with Ca/Mn molar ratio of 100:0.75 exhibits the best performance, and its carbonation conversions reach 0.76 and 0.59 in the 1st and 20th cycles, respectively, which are 28% and 18% higher than those of Ca(OH)(2). Furthermore, carbonation conversion of this Mn-modified Ca(OH)(2) decreases by within 1.00% from cycle 5 to 20. Mn addition boots oxygen vacancy, increases the surface area and pore volume, and reduces the energy barrier for carbonation of Ca(OH)(2). Mn-modified Ca(OH)(2) as CO2 sorbent appears promising.
Keywords:
carbonation-calcination-hydration cycles
CO2 uptake
density functional theory calculations
Mn-modified Ca(OH)(2)
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