Parametric study and effect of calcination and carbonation conditions on the CO2 capture performance of lithium orthosilicate sorbent

The world is currently facing the challenges of global warming and climate change. Numerous efforts have been taken to mitigate CO2 emission, among which is the use of solid sorbents for CO2 capture. In this work, Li4SiO4 was synthesised via a sol-gel method using lithium nitrate (LiNO3) and tetraethylorthosilicate (SiC8H20O4) as precursors. A parametric study of Li:Si molar ratio (1-5), calcination temperature (600-800 °C) and calcination time (1-8 h) were conducted during sorbent synthesis. Calcination temperature (700-800 °C) and carbonation temperature (500-700 °C) during CO2 sorption activity were also varied to confirm the optimum operating temperature. Sorbent with the highest CO2 sorption capacity was finally introduced to several cyclic tests to study the durability of the sorbent through 10 cycles of CO2 sorption-desorption test. The results showed that the calcination temperature of 800 °C and carbonation temperature of 700 °C were the best operating temperatures, with CO2 sorption capacity of 7.95 mmol CO2∙(g sorbent)− 1 (93% of the theoretical yield). Throughout the ten cyclic processes, CO2 sorption capacity of the sorbent had dropped approximately 16.2% from the first to the tenth cycle, which was a reasonable decline. Thus, it was concluded that Li4SiO4 is a potential CO2 solid sorbent for high temperature CO2 capture activity.