CO₂—H₂O Capture and Cyclability on Sodium Cobaltate at Low Temperatures (30–80 °C): Experimental and Theoretical Analysis

Abstract

Sodium cobaltate (NaCoO2) is analyzed for the CO2 cyclic carbonation–decarbonation process at low temperatures (30–80 °C) with relative humidity (RH) values between 0% and 80%, using water vapor as a catalytic intermediate. The presence of H2O clearly enhances the CO2 capture at T < 100 °C, compared with dry conditions, where the amount of CO2 captured increases as a function of RH. These improvements are attributed to the formation of NaHCO3 and Na2CO3 during carbonation. In the case of NaHCO3, water vapor becomes a part of carbonation, favoring reactivity. After the carbonation analysis, the decarbonation process is analyzed using a N2 flow, where results evidence that only NaHCO3 decomposition takes place at low temperatures, producing NaOH and CO2. This result indicates that NaCoO2 can be partially regenerated, suggesting a possible CO2 cyclic carbonation. CO2 carbonation–decarbonation tests are performed, confirming the cyclic capacity and stability. Moreover, the NaCoO2 sample is modified by adding different transition metals (Fe, Cu, and Ni) to improve CO2—H2O sorption under similar physicochemical conditions. Results indicate that Fe‐containing samples present the best properties. Finally, the effect of CO2 partial pressure on NaCoO2 and Fe‐containing samples is analyzed using similar RHs.

CO2 Capture at Medium to High Temperature Using Solid Oxide-Based Sorbents: Fundamental Aspects, Mechanistic Insights, and Recent Advances

“…526,527 Through XRD analysis of the cycled sorbents, Ochoa-Fernańdez et al indeed observed that the alkali metal content was lower than before the cycling experiment for ZrO 2 -containing sorbents, 518 whereas this was not observed for Li 4 SiO 4 and K-doped Li 4 SiO 4 . 518,526 As mentioned in section 2.1, the presence of steam is important to enable the fast CO 2 sorption of alkali-based carbonates or oxides at temperatures <100 °C (including Li 5 AlO 4 , Li 4 SiO 4 , Li 2 SiO 3 , Li 2 ZrO 3 , or Li 2 CuO 2 outlined above, but also NaCoO 2 , 528 Na 2 ZrO 3 , 529 and Na 2 SiO 3 530 ). The mechanism of the effect of steam on improving CO 2 sorption at such low temperatures is very much different compared to that at medium and high temperatures that are the focus of this review, and also differs when comparing carbonates with oxides.…”

“…As mentioned in section , the presence of steam is important to enable the fast CO 2 sorption of alkali-based carbonates or oxides at temperatures <100 °C (including Li 5 AlO 4 , Li 4 SiO 4 , Li 2 SiO 3 , Li 2 ZrO 3 , or Li 2 CuO 2 outlined above, but also NaCoO 2 , Na 2 ZrO 3 , and Na 2 SiO 3 ). The mechanism of the effect of steam on improving CO 2 sorption at such low temperatures is very much different compared to that at medium and high temperatures that are the focus of this review, and also differs when comparing carbonates with oxides.…”

Water-based asymmetric supercapacitors with 2.5 V wide potential and high energy density based on Na0.6CoO2 nanoarray formed via electrochemical oxidation

“…The samples after EO were characterized by FI-RT as well. In addition to the seismic bands at 1637 and 3431 cm À1 , new and different seismic bands were identified at 558 and 1447 cm À1 , corresponding to the formation of NaeO bond [30]. The appearance of NaeO bonds further proves the successful synthesis of Na 0.6 CoO 2 .…”

Chemisorption of SO2 and NO2 gas over Na0.4MnO2 in ambient conditions: an experimental and theoretical study

“…[3][4][5][6] Recently, these oxides have proven useful for the chemisorption of CO 2 gas. 7,8 The alkaline nature of Na metalates could be equally valuable for the chemisorption of other acidic gases. In our previous work, phase-pure Na 0.4 MnO 2 was studied for room-temperature oxidation of H 2 S and SO 2 gas.…”