Optimization of High-Temperature CO2 Capture by Lithium Orthosilicate-Based Sorbents Using Response Surface Methodology

The major challenge in the current context of the rising world energy demand is to limit the global temperature increase for mitigating climate change. This goal requires a large reduction of CO₂ emissions, mainly produced by power generation and industrial processes using fossil fuels. In this study, a novel methodology for K₂CO₃-doped Li4SiO4 sorbents production for CO₂ capture at high temperatures was adopted based on the Design of Experiments (DoE). This innovative approach systematically tested different synthesis (temperature and K₂CO₃ content) and adsorption conditions (sorption temperature and CO₂ concentration), allowing for the assessment of individual and interactive effects of process parameters. The Response Surface Methodology (RSM) was employed to obtain non-linear predictive models of CO₂ uptake and Li₄SiO₄ conversion. The results of RSM analysis evidenced a maximum adsorption capacity of 196.4 mg/g for a sorbent produced at 600 degrees C and with 36.9 wt% of K₂CO₃, tested at 500 degrees C and 4 vol% of CO₂. Whereas at 50 vol% of CO₂, the best uptake of 295.6 mg/g was obtained with a sorbent synthesized at 600 degrees C, containing less K₂CO₃ (17.1 wt%) and tested at a higher temperature (662 degrees C). These findings demonstrate that K₂CO₃-doped Li₄SiO₄ sorbents can be tailored to maximize CO₂ capture under various operating conditions, making them suitable for use in industrial processes.