Behaviors and kinetic models analysis of Li 4 SiO 4 under various CO 2 partial pressures

Cyclic CO2 absorption/desorption property of Li3NaSiO4 under the partial pressure of CO2 for practical applications

The temperature for realizing the cyclic CO2 absorption/desorption property of Li3NaSiO4 by repetition of switching a CO2/N2 gas mixture and N2 with a partial pressure of CO2, P(CO2), of 0.1 bar was optimized using the pseudo van't Hoff plot of LiNaCO3 + Li2SiO3 ↔ Li3NaSiO4 + CO2 prepared by thermogravimetry at various P(CO2) values.

Insight into CO selective chemisorption from syngas mixtures through Li2MnO3; a new H2 enrichment material

Li2MnO3 is able to selectively trap CO in the presence of H2 at high temperatures, favoring H2 enrichment from syngas flows.

A new method for the preparation of high-purity CO2-absorbing Li3NaSiO4 powder using lithium silicate and sodium carbonate

The starting materials and temperature for the preparation of Li₃NaSiO₄ powder, which has attracted attention as a CO₂ absorbent, were optimized in this study. Mixtures of Li₂CO₃, Na₂CO₃, and SiO₂ as well as Li₄SiO₄, Li₂SiO₃, and Na₂CO₃ were subjected to thermogravimetry-differential thermal analysis (TG-DTA) to elucidate their reaction mechanisms. The phase, morphology, specific surface area, and CO₂ absorption characteristics of the powder specimens that were obtained by heating the two mixtures were examined by X-ray diffraction (XRD), secondary electron microscopy (SEM), N₂ adsorption isotherm and isothermal TG-DTA. Melted LiNaCO₃ was generated via the heat treatment of the Li₂CO₃, Na₂CO₃, and SiO₂ powder mixture, yielding a low-purity bulk specimen with inhomogeneous particle size. However, the use of the Li₄SiO₄, Li₂SiO₃, and Na₂CO₃ mixture as a starting material ensured that no liquid phase was generated during heat treatment and successfully yielded Li₃NaSiO₄ powder which was purer than the product derived from the Li₂CO₃/Na₂CO₃/SiO₂ mixture, presumably because of the lower volatility of Li and Na in the solid phase than that in the liquid phase of LiNaCO₃. The Li₃NaSiO₄ powder derived from Li₄SiO₄, Li₂SiO₃, and Na₂CO₃ showed a slightly larger surface area with homogeneous particle size and almost identical CO₂ absorption kinetics compared to those of the product obtained from Li₂CO₃, Na₂CO₃, and SiO₂, in addition to absorbing a higher amount of CO₂ owing to its higher purity.

From Spent Lithium-Ion Batteries to Low-Cost Li4SiO4 Sorbent for CO2 Capture

The huge consumption of fossil fuels leads to excessive CO₂ emissions, and its reduction has become an urgent worldwide concern. The combination of renewable energies with battery energy storage, and carbon capture, utilization, and storage are well acknowledged as two major paths in achieving carbon neutrality. However, the former route faces the discard problem of a large amount of lithium-ion batteries (LIBs) due to their limited lifespan, while it is costly to obtain effective CO₂-capturing materials to put the latter into implementation. Herein, for the first time, we propose a route to synthesize low-cost Li₄SiO₄ as CO₂ sorbents from spent LIBs, verify the technical feasibility, and evaluate the CO₂ adsorption/desorption performance. The results show that Li₄SiO₄ synthesized from the cathode with self-reduction by the anode graphite of LIBs has a superior CO₂ capacity and cyclic stability, which is constant at around 0.19 g/g under 15 vol % CO₂ after 80 cycles. Moreover, the cost of fabricating sorbents from LIBs is only 1/20-1/3 of the conventional methods. We think this work can not only promote the recycling of spent LIBs but also greatly reduce the cost of preparing Li₄SiO₄ sorbents, and thus could be of great significance for the development of CO₂ adsorption.

Enhanced CO capture properties of Li2MnO3via inducing layered to spinel transition by cation doping with Fe, Co, Ni and Cu

Lithium manganate (Li2MnO3) was the first alkaline ceramic to show selective CO chemisorption in non-oxidative atmospheres, which is of interest for gas separation processes, such as high purity H2 production.

Elucidating the promotion of Na2CO3 in CO2 capture by Li4SiO4

Although Li₄SiO₄-based sorbents are candidates for CO₂ capture at high temperatures, it is still necessary to improve their kinetic activation for adsorption and desorption. Carbonate doping to Li₄SiO₄ is considered as one of the effective means to improve CO₂ capture by Li₄SiO₄. In this study, Li₄SiO₄ was synthesized using Li₂CO₃ and SiO₂ at 900 °C, and mixed with different amounts of Na₂CO₃ as CO₂ sorbents. The effects of Na₂CO₃ on the absorption and desorption were characterized using thermal analyses in an atmosphere of 80 vol% CO₂-20 vol% N₂. In situ Raman and XRD were used for the characterization of the structural transformations and phase evolution during the CO₂ capture. The activation energy of both chemisorption and diffusion in adsorption dropped significantly. The additive Na₂CO₃ can react with CO₂ and produce the pyrocarbonate, which is favorable for CO₂ capture of Li₄SiO₄ and CO₂ diffusion. The doped Na₂CO₃ served two functions: producing the intermediate product and forming the melt with the product Li₂CO₃ to accelerate CO₂ transport. The Na₂CO₃-doped Li₄SiO₄ exhibits stable cyclic durability with conversions of 75% in 20 adsorption-desorption cycles.

CO2 Capture at Medium to High Temperature Using Solid Oxide-Based Sorbents: Fundamental Aspects, Mechanistic Insights, and Recent Advances

Carbon dioxide capture and mitigation form a key part of the technological response to combat climate change and reduce CO₂ emissions. Solid materials capable of reversibly absorbing CO₂ have been the focus of intense research for the past two decades, with promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this review, we explore the fundamental aspects underpinning solid CO₂ sorbents based on alkali and alkaline earth metal oxides operating at medium to high temperature: how their structure, chemical composition, and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines, including materials discovery, synthesis, and in situ characterization, to present a coherent understanding of the mechanisms of CO₂ absorption both at surfaces and within solid materials.

Thermodynamics and kinetics analyses of high CO2 absorption properties of Li3NaSiO4 under various CO2 partial pressures

The temperature and P(CO₂) region for the reaction between Li₃NaSiO₄ and CO₂ is similar to that of Li₄SiO₄. However, Li₃NaSiO₄ shows higher CO₂ absorption kinetics.

In situ Raman and XRD study of CO2 sorption and desorption in air by a Na4SiO4-Na2CO3 hybrid sorbent

Silicate-carbonate mixtures as new CO2 capture agents have the latent application potential. CO2 sorption or desorption processes using the Na4SiO4-Na2CO3 mixture sorbent in air were analyzed by in situ Raman spectroscopy and X-ray diffraction from 25 °C to 900 °C. The results show that the Na4SiO4-Na2CO3 mixture sorbent could continuously absorb and strip CO2 by thermal swinging. The CO2 sorption was produced via a two-step process depending on the temperature range. Initially, CO2 dissolved in carbonate to produce pyrocarbonate (C2O52-) ions, which subsequently reacted with SiO44- anion to produce the polymer silicates and CO32- anion. The C2O52- anion on the surface of the silicates promoted CO2 transformation to CO32- anion through the reaction with SiO44- anions. The CO32- anion decomposed the polymer silicates to produce orthosilicates and CO2 gas again at high temperature. By this circulation, CO2 could dissolve in carbonate more easily and be absorbed and stripped continuously by thermal swinging in the mixture sorbent than the pure carbonate. The processes of recovering heat and separating CO2 from flue gas simultaneously without decreasing the temperature is an economical and attractive method for energy conservation. It offers the theoretical basis for developing new heat-storage and CO2-capture technology.

Evaluation of Fe-containing Li2CuO2 on CO2 capture performed at different physicochemical conditions

Li₂CuO₂ and different iron-containing Li₂CuO₂ samples were synthesized by solid state reaction. On iron-containing samples, atomic sites of copper are substituted by iron ions in the lattice (XRD and Rietveld analyses). Iron addition induces copper release from Li₂CuO₂, which produce cationic vacancies and CuO, due to copper (Cu²⁺) and iron (Fe³⁺) valence differences. Two different physicochemical conditions were used for analyzing CO₂ capture on these samples; (i) high temperature and (ii) low temperature in presence of water vapor. At high temperatures, iron addition increased CO₂ chemisorption, due to structural and chemical variations on Li₂CuO₂. Kinetic analysis performed by first order reaction and Eyring models evidenced that iron addition on Li₂CuO₂ induced a faster CO₂ chemisorption but a higher thermal dependence. Conversely, CO₂ chemisorption at low temperature in water vapor presence practically did not vary by iron addition, although hydration and hydroxylation processes were enhanced. Moreover, under these physicochemical conditions the whole sorption process became slower on iron-containing samples, due to metal oxides presence.

Kinetic analysis for cyclic CO2 capture using lithium orthosilicate sorbents derived from different silicon precursors

The illustration of the CO₂ sorption process in Li₄SiO₄.