Textural, Structural, and CO₂ Chemisorption Effects Produced on the Lithium Orthosilicate by Its Doping with Sodium (Li_4−xNa_xSiO₄)

Abstract

Solid solutions of lithium and sodium orthosilicate (Li 4-x Na x SiO 4 ) were synthesized by coprecipitation. Samples were characterized by powder X-ray diffraction, scanning electron microscopy, N 2 adsorption, and thermogravimetric analyses (dynamic and isothermically). Results showed that the solubility limit of sodium into Li 4 SiO 4 is 0.1, Li 3.9 Na 0.1 SiO 4 . Sodium additions, higher than 0.1, produced the formation of secondary phases. Thermal analyses into a CO 2 flux showed that Li 4-x Na x SiO 4 solid solutions present a much better CO 2 absorption than that observed for pure Li 4 SiO 4 . Isothermal analyses were performed to the samples in order to obtain kinetic information. These data were adjusted to double exponential model as there are two different processes taking place, the CO 2 absorption and diffusion processes. Nevertheless, in some cases, it was detected the presence of a third process, desorption. Those experiments were fitted to a triple exponential model. Finally the enthalpy activation energies for the different processes were calculated using the Eyring's model.

Effects of Calcination Temperature on the Structure and CO2 Sorption Properties of Li4SiO4 Sorbents from Rice Husk Ash

“…Especially Li-1000RHA even obtained with 33.6 wt % maximum absorption, which corresponded to 91.6% efficiency. This higher capacity of Li 4 SiO 4 sorbents were also observed using sodium orthosilicates [12] and RHA-Li 4 SiO 4 sorbent [8].…”

Influence of the K‐, Na‐ and K‐Na‐carbonate additions during the CO2 chemisorption on lithium oxosilicate (Li8SiO6)

“…Powders were mixed and then thermally treated at 800 °C for 8 h. A lithium excess of 15 wt% was used to prevent lithium sublimation. 22,32,34 Aft er the Li 8 SiO 6 synthesis, the powder was mechanically mixed with 10 wt% of sodium carbonate (Na 2 CO 3 , Aldrich), or potassium carbonate (K 2 CO 3 , Aldrich), or a 50:50 wt% mixture of both carbonates (20 wt% in total). Th e samples were labeled as follow: Th e Na 2 CO 3 -Li 8 SiO 6 sample was labeled as Na-Li 8 SiO 6 , the K 2 CO 3 -Li 8 SiO 6 sample was labeled as K-Li 8 SiO 6 and the K 2 CO 3 -Na 2 CO 3 -Li 8 SiO 6 sample was labeled as K-Na-Li 8 SiO 6 .…”

Development of sodium/lithium/fly ash sorbents for high temperature post-combustion CO 2 capture

“…Some studies have indicated that alkaline solid mixtures such as lithium-sodium zirconate, lithium-potassium zirconate and Li-Na ortho-silicate present better CO 2 sorption than pure lithium or sodium zirconate [27]. The latter work showed that the solubility limit of sodium into Li 4 SiO 4 is 0.025% (Li 3.9 Na 0.1 SiO 4 ) and that addition of Na larger than 0.025% produces secondary silicate phase [27].…”