Ultrafast Carbon Dioxide Sorption Kinetics Using Lithium Silicate Nanowires

Abstract

In this paper, the Li₄SiO₄ nanowires (NWs) were shown to be promising for CO₂ capture with ultrafast kinetics. Specifically, the nanowire powders exhibited an uptake of 0.35 g g^-1 of CO₂ at an ultrafast adsorption rate of 0.22 g g^-1 min^-1 at 650-700 °C. Lithium silicate (Li₄SiO₄) nanowires and nanopowders were synthesized using a "solvo-plasma" technique involving plasma oxidation of silicon precursors mixed with lithium hydroxide. The kinetic parameter values (k) extracted from sorption kinetics obtained using NW powders are 1 order of magnitude higher than those previously reported for the Li₄SiO₄-CO₂ reaction system. The time scales for CO₂ sorption using nanowires are approximately 3 min and two orders magnitude faster compared to those obtained using lithium silicate powders with spherical morphologies and aggregates. Furthermore, Li₄SiO₄ nanowire powders showed reversibility through sorption-desorption cycles indicating their suitability for CO₂ capture applications. All of the morphologies of Li₄SiO₄ powders exhibited a double exponential behavior in the adsorption kinetics indicating two distinct time constants for kinetic and the mass transfer limited regimes.