Brenda Alcántar-Vázquez

Carbon dioxide capture in the presence of water vapour in InOF-1

Kinetic uptake experiments on InOF-1 confirm a maximum of 5.42 wt% CO2 capture at 30 °C and a significant 2-fold increase (∼11 wt%) in CO2 capture under 20% relative humidity of water vapour. InOF-1 captures CO2 under humid conditions (10% and 20% RH) and at relatively high temperatures (40 and 50 °C) without any degradation of the crystalline structure which was corroborated by PXRD.

Water steam effect during high CO2 chemisorption in lithium cuprate (Li2CuO2) at moderate temperatures: experimental and theoretical evidence

Li2CuO2 was evaluated as a CO2 captor at moderate temperatures, using water vapor in the gas flow. Different water vapor sorption experiments were performed using N2 or CO2 as carrier gases. If N2 was used as carrier gas, it was evidenced that Li2CuO2 is able to trap water physically and chemically, producing in the second case Li–OH superficial species. Moreover, when CO2 was used as carrier gas, Li2CuO2 continued trapping water, as in the previous case, but in this case CO2 was mainly trapped, forming Li2CO3 and CuO phases. Additionally, the microstructure changes importantly when CO2 and H2O are chemically trapped in Li2CuO2. Li2CO3 and CuO seemed to segregate changing the morphology and the specific surface area. The Li2CuO2 sample was able to capture up to 6.7 mmoles of CO2 per gram of ceramic at 80 °C, a considerably high CO2 amount. Furthermore, all these experiments were theoretically supported by different thermodynamic calculations. Experimental and theoretical results show that H2O acts as a catalytic intermediate, diminishing the activation energy of the whole CO2 chemisorption process. Therefore, the presence of water vapor strongly favored the CO2 chemisorption on Li2CuO2 at moderate temperatures (30–80 °C).

Bifunctional application of sodium cobaltate as a catalyst and captor through CO oxidation and subsequent CO2 chemisorption processes

The potential bifunctional mechanism of sodium cobaltate (NaCoO2) in the catalysis of CO oxidation and subsequent CO2 chemisorption was systematically analysed. Different catalytic and gravimetric experiments were performed dynamically and isothermally at multiple temperatures. Initially, the CO oxidation process was evaluated using a catalytic reactor connected to a gas chromatograph. Once the production of CO2 was confirmed, its chemisorption capacity with NaCoO2 was studied gravimetrically. Catalytic and gravimetric analysis products were studied by XRD, FTIR and SEM to elucidate the double reaction mechanism. Sodium cobaltate exhibited interesting catalytic properties over a wide temperature range, although the NaCoO2 crystalline structure and chemical composition changed during the CO2 capture process. Furthermore, all the experiments were theoretically supported by first-principles density functional theory thermodynamic calculations. The calculated thermodynamic properties of the CO oxidation and CO2 capture reactions with NaCoO2 under different oxidation conditions were in good agreement with the experimental measurements.

Structural and microstructural analysis of different CaO–NiO composites and their application as CO2 or CO–O2 captors

In this work, CaO–NiO mixed oxide powders were prepared by mechanical mixing and incipient impregnation methods. The samples were characterized structurally and microstructurally, where it was determined that microstructural properties changed depending on the NiO addition method. The CO2 and CO–O2 capture evaluations were performed in a thermogravimetric analyzer. These results showed that the presence of nickel significantly modified the CO2 and CO capture processes. In both cases, the CO2 or CO capture temperature was shifted to lower values in the CaO–NiO composites in comparison to the CaO sample. Nevertheless, the carbon oxide captures seemed to decrease as a function of the nickel addition. It was associated to the nickel superficial deposition over the CaO particles. On the other hand, the CO–O2 oxidation was importantly enhanced and maintained, for long times, with the presence of nickel independently of the calcium oxide carbonation process.