Synthesis and evaluation in the CO2 capture process of potassium-modified lithium silicates produced from steel metallurgical slags

Abstract Lithium silicate-based CO2 sorbents were successfully synthesized using steel metallurgical slags as silica sources, with and without K 2CO3 addition (10−30 wt%). The CO2 capture efficiency improved with K2CO3 addition because of the formation of a eutectic phase between K2CO3 and Li2CO3, which facilitated CO2 diffusion into the material bulk. The best capture capacity value (104 mgCO2/gmaterial) was obtained using the material produced from steel metallurgical slag with 20 wt% K2CO3 (SK0.2) at 600 °C and with either 5 or 20 vol% CO2. In addition, the CO2 capture rate increased up to four orders of magnitude in the diffusion-controlled stage compared to material prepared with fumed silica or F (K2 = 2.89 E-3 s−1 for SK0.2 and K2 = 4.21 E-8 s−1 for F). After 20 adsorption-desorption cycles using 20 vol% CO2, the CO2 capture capacity of SK0.2 was reduced by only 10 %, indicating excellent thermal stability.