Synthesis of LiF-Containing Li₄SiO₄ as Highly Efficient CO₂ Sorbents

Abstract

Several types of lithium halide-containing Li 4 SiO 4 sorbents were prepared via sacrificial carbon template technology to overcome the typical kinetic limitations under low CO 2 partial pressures. The synthesized samples were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), N 2 adsorption, XPS (X-ray photoelectron spectroscopy), and thermogravimetric analysis. The results reveal that among three lithium halide-containing Li 4 SiO 4 sorbents, the highest uptakes were obtained by LiF addition. Different amounts of LiF addition also significantly affected the intrinsic properties and absorption characteristics of the Li 4 SiO 4 sorbents. When the addition amount was 10 mol %, Li and F were incorporated into the Li 4 SiO 4 structure to form a solid solution. Such features generated smaller crystallite sizes and particle sizes as well as a species of Li 2 O on Li 4 SiO 4 surface, which was responsible for the maximum uptake capacity of 36.2 wt % at 575 °C under 15 vol % CO 2 . This value is the largest uptake reported in the literature to date. Moreover, a high capacity was maintained over eight sorption/desorption cycles.

Sorption of CO2 on NaBr co-doped Li4SiO4 ceramics: Structural and kinetic analysis

“…6 and the activation enthalpies were obtained from the slope. Compared with pure Li4SiO4 reported in previous studies [40,54], the ∆H ++ values of the surface chemisorption processes for SCT-NaCl-0.1 and SCT-NaBr-0.1 were greatly reduced, indicating the surface chemisorption process was less dependent on temperature when doping with NaCl/NaBr. Moreover, a decrease in the ∆H ++ value of NaBr doping for surface chemisorption was observed as compared with the case of NaCl doping, indicating that its surface chemisorption was less reliant on temperature.…”

Enhanced carbon dioxide capture performance of natural mineral vermiculite‐derived lithium silicate with Na doping

“…The results showed that the adsorbents could still maintain an adsorption capacity of 0.32 g CO 2 /g adsorbent after 10 cycles under a15% CO 2 . Similarly, Wang et al 38 doped 3 wt% NaF into Li 4 SiO 4 by a solid-state method, and this adsorbent exhibited the fastest adsorption rate and maximum adsorption capacity of over 0.33 g CO 2 /g adsorbent , which was attributed to the high concentration of Li-O sites on the molten surface, thereby facilitating the superficial CO 2 chemisorption process.…”

New Catalytic and Sorption Bifunctional Li6CoO4 Material for Carbon Monoxide Oxidation and Subsequent Chemisorption

“…Carbon oxides (CO and CO 2 ) separation, capture, and catalytic conversion from different composition gas flows have become some of the most important issues from the environmental point of view. , Within this context, in the last two decades, different alkaline and alkaline earth ceramics have been proposed as possible CO 2 capture materials . Calcium oxide (CaO), lithium silicates (Li 4 SiO 4 and Li 8 SiO 6 ), ,− and alkaline zirconates (Li 2 ZrO 3 and Na 2 ZrO 3 ) ,− were proposed as CO 2 chemisorbents at high temperatures, presenting different advantages and disadvantages. However, in recent years, new alkaline ceramics have been proposed for this application. − Some examples include lithium cuprate (Li 2 CuO 2 ), − as well as lithium and sodium ferrites (Li 5 FeO 4 , LiFeO 2 , and NaFeO 2 ), ,− which have shown great properties, mainly due to the redox capacity of the transition metals present in these samples.…”