Synthesis of Li4+xSi1−xFexO4 solid solution by dry ball milling and its highly efficient CO2 chemisorption in a wide temperature range and low CO2 concentrations

Abstract

To be considered a good CO₂ capture material for industrial applications, alkaline ceramics have to present several properties such as fast sorption and desorption kinetics, large sorption capacities, regenerability and stability, and a wide operating temperature range. In this sense, Li₄SiO₄ fulfills some of these features, although it has some kinetic disadvantages at temperatures lower than 500 °C and under low CO₂ partial pressures. Herein, we show an easy an efficient way to synthesize a Fe-containing Li₄SiO₄ solid solution (Li_4+xSi_1−xFe_xO₄, with x ≤ 0.5); by a dry ball milling synthesis, with high CO₂ capture capacities. A synergic effect, between the microstructural features given by the proposed synthesis method and the iron content, improves the CO₂ capture exhibited by the material in different ways: (1) Li_4+xSi_1−xFe_xO₄ solid solution samples are able to trap large amounts of CO₂ between 200 and 650 °C. At 200 °C, the solid solution chemisorbs 11 wt% of CO₂, the largest amount of CO₂ captured reported so far in the literature at this temperature; (2) iron containing samples diminish the CO₂ capture dependence on temperature; (3) CO₂ capture was considerably improved under low partial pressures of CO₂ and (4) iron redox properties enhanced the CO₂ capture, by using a low partial pressure of O₂.