Li4SiO4-based adsorbents for CO2 capture at high temperature: performance enhancement by ball milling process

Post-combustion capture technologies based on regenerable solid sorbents are attracting increasing attention as ways to reduce CO2 emissions. The present study focused on the fabrication at industrial lab-scale of lithium orthosilicate (Li4SiO4) sorbents for CO2 capture at high temperature and low concentration. The ball milling process was used during the reagents mixing phase to modify the microstructure of the obtained Li4SiO4 powders. The CO2 sorption properties of the sorbents were studied in a controlled gas flow environment at low CO2 concentration (4 vol%). The effect of different milling times (0-120 min) on the sorption performance of the sorbents was investigated together with the effect of the adsorption temperature (470-570 °C) by using the Response Surface Methodology, and predictive models for the Li4SiO4 conversion and the adsorption rate were developed. The results evidenced that the ball milling process increased the pure Li4SiO4 sorption performance, reaching a maximum sorption capacity of 156mg CO2/g sorbent for 80 min of milling and adsorption temperature of 515 °C.