Impregnation Precipitation Preparation and Kinetic Analysis of Li₄SiO₄-Based Sorbents with Fast CO₂ Adsorption Rate

Abstract

Li4SiO4-based sorbents from diatomite with fast CO2 adsorption rate (achieving the adsorption equilibrium at about 15 min) were developed by the impregnation precipitation method at lower temperature (600 °C). Influence of sintering temperatures on phase composition was investigated. Phase composition and morphologies were analyzed by XRD and SEM, and CO2 adsorption properties were investigated by TG. The as-prepared Li4SiO4-based sorbents reached a higher adsorption capacity of 34.02 wt % (7.73 mmol CO2/g Li4SiO4, corresponding to 92.70% efficiency) in a mixture gas (50 mL/min N2 and 50 mL/min CO2). The activation energies for chemisorption (28.868 kJ/mol) and diffusion (16.563 kJ/mol) were obtained by isothermal study. Compared with our previous research results by the solid reaction method, the activation energies for these two processes decreased measurably. In addition, the as-prepared Li4SiO4-based sorbents also exhibited faster adsorption rate and better adsorption–desorption performance.