Development of Alkali Nitrate-Containing Li4SiO4 for High-Temperature CO2 Capture

High efficiency alkali nitrate-containing Li4SiO4 sorbents were synthesized by a hydration technique to improve their sorption performances at low CO2 concentrations. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and thermogravimetric analyses were used to detect the characteristics of the samples. The results showed that the presence of KNO3 and NaNO3 induced small crystallite size, corrugated morphologies and the formation of eutectic phases, noticeably facilitating sorption processes. At the optimized additive amount of 0.035 mol %, NaNO3-containing Li4SiO4 reached a maximum absorption capacity (approximate to 34.6 wt %). Moreover, both alkali nitrate-containing Li4SiO4 sorbents showed good cyclic properties, demonstrating their great potential for high-temperature CO2 capture.