Sodium metatitanate (Na2TiO3) was successfully synthesized via a solid-state reaction. The Na2TiO3 structure and microstructure were characterized using X-ray diffraction, scanning and transmission electron microscopy, and N2 adsorption. Then, the CO2 chemisorption mechanism on Na2TiO3 was systematically analyzed to determine the influence of temperature. The CO2 chemisorption capacity of Na2TiO3 was evaluated both dynamically and isothermally, and the products were reanalyzed to elucidate the Na2TiO3–CO2 reaction mechanism. Different chemical species (Na2CO3, Na2O, and Na4Ti5O12 or Na16Ti10O28) were identified during the CO2 capture process in Na2TiO3. In addition, some CO2 chemisorption kinetic parameters were determined. The Δ H ⧧ was found to be 140.9 kJ/mol, to the Na2TiO3–CO2 system, between 600 and 780 °C. Results evidenced that CO2 chemisorption on Na2TiO3 highly depends on the reaction temperature. Furthermore, the experiments were theoretically supported by different thermodynamic calculations. The calculated thermodynamic properties of CO2 capture reactions by (Na2TiO3, Na4Ti5O12, and Na16Ti10O28) sodium titanates were fully investigated.

Pentalithium ferrite (Li 5 FeO 4 ) was tested as possible CO 2 captor, both by theoretical calculations and experimental measurements. The pristine Li 5 FeO 4 compound with orthorhombic structure was synthesized via solid-state reaction and it was structural and microstructurally characterized. Later, sample was heat-treated at temperatures from room temperature to 900 °C under different CO 2 or CO 2 −O 2 atmospheres. Li 5 FeO 4 exhibits excellent CO 2 chemisorption abilities with a capture capacity about 12.9 mmol/g, which is outstanding in comparison to other previously reported ceramic captors. This material is able to react with CO 2 from 200 °C to approximately 715 °C showing a high kinetic of reaction even at CO 2 partial pressure values as low as 0.2. Additionally, results suggest that oxygen addition does enhance the CO 2 chemisorption on Li 5 FeO 4 at temperatures below 700 °C, although oxygen addition seems to favor the desorption process at higher temperatures.

From a binary equimolar gas-mixture of CO 2 and CH 4 , NOTT-401 exhibits CO 2 separation from CH 4 . By kinetic uptake experiments, NOTT-401 shows a maximum of 1.47 wt% CO 2 capture at 30°C and a significant 7-fold increase (∼9.90 wt%) in CO 2 capture under 40% relative humidity. † Electronic supplementary information (ESI) available: TGA data, PXRDP data, FTIR data, polynomial regressions and kinetic uptake experiments. See

NOTTS-400 exhibits CO2separation from CH4when the material was exposed to a binary (CO2/CH4) equimolar gas-mixture and this was confirmed byin situFTIR spectroscopy.