Enhanced CO2 absorption kinetics in lithium silicate platelets synthesized by a sol–gel approach

Abstract

Platelet-shaped lithium orthosilicate particles synthesized by a sol–gel approach employing the precursors lithium nitrate and colloidal silica displayed enhanced absorption kinetics for CO₂ compared to the powders prepared by a solid-state reaction process involving Li₂CO₃ and silica. The sol–gel samples showed a CO₂ absorption capacity of 350 mg g⁻¹ at an absorption rate of 22.5 mg g⁻¹ min⁻¹, a value 70% higher than the rate of 13.2 mg g⁻¹ min⁻¹ measured with the solid-state samples under similar conditions. The higher sorption kinetics of CO₂ by the sol–gel derived lithium orthosilicate could be attributed to the unique platelet morphology of the particles, which have a very small thickness. A porous carbon mesh coated with the sol–gel based particles exhibited CO₂ absorption capacity of 150 mg g⁻¹ at an absorption rate of 37.5 mg g⁻¹ min⁻¹. This supported absorbent also showed stable absorption and desorption performance for the 8 cycles examined in this study. The excellent absorption characteristics of the sol–gel prepared powders, more specifically the coated strips, provide a successful pathway for the commercialisation of these materials.