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

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 degrees C and under low CO2 partial pressures. Herein, we show an easy an efficient way to synthesize a Fe-containing Li4SiO4 solid solution (Li4+xSi1-xFexO4, 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) Li4+xSi1-xFexO4 solid solution samples are able to trap large amounts of CO2 between 200 and 650 degrees C. At 200 degrees 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 O-2.