Synthesis of Li _{4+: X} Si _{1- x} Fe _x O ₄ solid solution by dry ball milling and its highly efficient CO ₂ chemisorption in a wide temperature range and low CO ₂ concentrations

To be considered a good CO ₂ 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, Li ₄ SiO ₄ fulfills some of these features, although it has some kinetic disadvantages at temperatures lower than 500 °C and under low CO ₂ partial pressures. Herein, we show an easy an efficient way to synthesize a Fe-containing Li ₄ SiO ₄ solid solution (Li _4+x Si _1-x Fe _x O ₄ , with x ≤ 0.5); by a dry ball milling synthesis, with high CO ₂ capture capacities. A synergic effect, between the microstructural features given by the proposed synthesis method and the iron content, improves the CO ₂ capture exhibited by the material in different ways: (1) Li _4+x Si _1-x Fe _x O ₄ solid solution samples are able to trap large amounts of CO ₂ between 200 and 650 °C. At 200 °C, the solid solution chemisorbs 11 wt% of CO ₂ , the largest amount of CO ₂ captured reported so far in the literature at this temperature; (2) iron containing samples diminish the CO ₂ capture dependence on temperature; (3) CO ₂ capture was considerably improved under low partial pressures of CO ₂ and (4) iron redox properties enhanced the CO ₂ capture, by using a low partial pressure of O ₂ .