Li4SiO4-based Adsorbents for CO2 Capture at High Temperature: Performance Enhancement by Ball-milling Process

Abstract

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 156 mg CO₂/g sorbent for 80 min of milling and adsorption temperature of 515 °C.