Development of Alkali Nitrate‐Containing Li₄SiO₄ for High‐Temperature CO₂ Capture

Abstract

High efficiency alkali nitrate‐containing Li4SiO4 sorbents were synthesized by a hydration technique to improve their sorption performances at low CO2 concentrations. X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and thermogravimetric analyses were used to detect the characteristics of the samples. The results showed that the presence of KNO3 and NaNO3 induced small crystallite size, corrugated morphologies and the formation of eutectic phases, noticeably facilitating sorption processes. At the optimized additive amount of 0.035 mol %, NaNO3‐containing Li4SiO4 reached a maximum absorption capacity (≈34.6 wt %). Moreover, both alkali nitrate‐containing Li4SiO4 sorbents showed good cyclic properties, demonstrating their great potential for high‐temperature CO2 capture.

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

“…Interestingly, the maximum CO2 capture capacity of SCT-NaCl-0.1 was slightly higher than that of SCT-NaBr-0.1. Similar results have also been seen for alkali nitrates-doped Li4SiO4 sorbents [53]. At higher temperature (575°C), lithium diffusion resistance was greatly reduced.…”

Molten shell-activated, high-performance, un-doped Li4SiO4 for high-temperature CO2 capture at low CO2 concentrations

“…2, the ∆H ++ values for the surface sorption process obtained were 18.7 kJ/mol for MC-0.6. This value is remarkably smaller than the case of other pure Li4SiO4 sorbents using different preparation methods [44,45], implying that surface sorption for MC-0.6 is less reliant on temperature. While for the bulk diffusion period, the ∆H ++ of MC-0.6 was 54.0 kJ/mol, which is smaller than the case of other pure Li4SiO4 sorbents as previously reported [44,45].…”

“…This value is remarkably smaller than the case of other pure Li4SiO4 sorbents using different preparation methods [44,45], implying that surface sorption for MC-0.6 is less reliant on temperature. While for the bulk diffusion period, the ∆H ++ of MC-0.6 was 54.0 kJ/mol, which is smaller than the case of other pure Li4SiO4 sorbents as previously reported [44,45]. Apparently, MC-0.6 has lower activation enthalpies for both the surface-sorption and diffusion processes, mainly attributed by its large specific surface area and small particle/crystal size, which will be confirmed by the following characterization results.…”

Synthetic solid oxide sorbents for CO2 capture: state-of-the art and future perspectives

“…Na 2 CO 3 , K 2 CO 3 , NaNO 3 and KNO 3 , can accelerate the transport of CO 2 through the Li 2 CO 3 product layer, analogous to the case of alkali metal salt doped MgO sorbents). 119,121,120 Lastly, redox-active dopants, such as Fe 3+ , can improve the transport of O 2− ions through the Li 2 SiO 3 product layer. 118 Synthetically, doping can be achieved by including dopant precursors during the solid state synthesis of the Li 4 SiO 4 sorbent, 116,117 impregnating the solid-state synthesised Li Please do not adjust margins Please do not adjust margins CO 2 uptake (up to 35 wt.%, i.e.…”