Thermokinetic Analysis of Carbon Dioxide Chemical Capture Using a Nickel-Containing Alkaline Ceramic (Li ₂ NiO ₂ )

Dilithium nickel(II) oxide (Li2NiO2) was synthesized by a solid-state reaction and structurally and microstructurally characterized. Then, it was tested as a carbon dioxide (CO2) chemisorbent through dynamic and isothermal thermogravimetric analyses. Sample characterization indicated that the synthesized Li2NiO2 contained a small highly dispersed NiO phase as a secondary phase. CO2 capture performed on Li2NiO2, through dynamic experiments using different carbon dioxide partial pressures, showed that it had a low CO2 uptake at low temperatures (200–500 °C) but much higher uptakes at higher temperatures (550–700 °C) regardless of the CO2 concentration. Isothermal trends and solid product characterization allowed us to elucidate the reaction pathway, implying the lithium-deficient (Li1–xNixO2) crystal phase formation as reactive intermediates, as well as nickel oxide and lithium carbonate as final products. The reaction path evolution showed that low CO2 concentrations modified the external core–shell microstructure (porosity and specific surface area), which consequently favored CO2 capture. Complementarily, a kinetic analysis was performed via the Avrami–Erofeev model, the results of which were compared against different alkaline ceramics used for CO2 capture at high temperatures, revealing the positive performance of Li2NiO2.