Abstract

Binary liquid doping of Na/K with various molar ratios into lithium orthosilicate (Li3.92NaxKySiO4) were synthesized by citric acid-assisted sol-gel methods. The CO₂ sorption capacity of Li_3.92Na_xKySiO₄ was investigated by TG analysis under a gas stream containing 50% CO2 and 50% N2 in a wide range from room temperature to 900 0C. Results indicated the sorption of CO₂ for the different Na/K doping lithium orthosilicate occurred between 480-700 0C and the maximum sorption of CO2 was obtained at approximately 700 0C. The optimum ratio of binary doping of Na/K into lithium orthosilicate was determined to be 1:1 (Li_3.92Na_0.04K_0.04SiO₄) and the maximum sorption of CO₂ may attain up to 30.7% (g/g) under the condition of optimum Na/K doping ratio, implying synergetic enhancement effect of Na and K elements on doping vacancies into the Li4SiO4 lattice may enhance the CO₂ sorption capacity.

Keywords: Citric acid-assisted sol-gel, CO₂ capture, heterogeneous catalysis, lithium orthosilicate, Na/K doping, synergetic effect.