Synthesis and CO2 capture evaluation of Li2−xKxZrO3 solid solutions and crystal structure of a new lithium–potassium zirconate phase

Solid solutions of lithium and potassium metazirconates Li2−xKxZrO3 (where, 0⩽x⩽2) were prepared by coprecipitation. Samples were characterized by powder X-ray diffraction, scanning electron microscopy, and thermogravimetric analyses. Results showed that the solubility limits of potassium into Li2ZrO3 is x=0.2. Furthermore, at higher potassium concentrations, a new phase was synthesized, Li2.27K1.19Zr2.16O6.05. For structural studies of this new phase, XRD data were analyzed by Rietveld refinements. Additionally, at high potassium concentrations different phases of ZrO2 were found, as potassium tends to sublimate. On the other hand, lithium–potassium metazirconate solid solutions, Li2−xKxZrO3, were tested as CO2 captors. Thermal analyses into a CO2 flux showed that Li2−xKxZr2O3 solid solutions present a better CO2 absorption than Li2ZrO3 pure. The differences observed in the CO2 sorption processes were explained with thermodynamic data.