Capture Performance Research Articles

Design of ultrathin cross-linked poly(ethylene oxide) selective layer for high-performance CO2 capture

Cross-linked poly(ethylene oxide) (PEO) is a highly promising membrane material for CO2 capture, as it allows fast and selective CO2 transport. However, the facile fabrication of an ultrathin cross-linked PEO selective layer for thin-film composite (TFC) membrane to achieve high CO2 separation performance remains challenging. To address this issue, we reported the design of a soluble high-permeability cross-linked PEO polymer and the fabrication of it into an ultrathin CO2-selective layer through a simple coating technique. The as-synthesized cross-linked PEO polymer contains abundant poly(dimethylsiloxane) (PDMS) segments, leading to highly improved free volume and affinity towards CO2, which result in high CO2 diffusivity, solubility, and consequently high CO2 permeability (528 Barrer). TFC membranes with an ultrathin selective layer (∼128 nm) were successfully fabricated using the PEO polymer, leading to superior CO2 capture performance (CO2 permeance = 2650 GPU, CO2/N2 = 20) for CO2/N2 mixture separation in a long-term stability test, exceeding the target performance for carbon capture. Given their high separation performance, excellent stability, and scalable fabrication route, our PEO-based membranes hold great promise for post-combustion CO2 capture.

Multi-stage solvent circulation absorption enhancement: System optimization for energy-saving CO2 capture

One of the major barriers in industrial applications of solvent-based CO2 capture is the significant energy consumption required for absorbent regeneration. In this study, a novel multi-stage circulation (MSC) CO2 absorption process was proposed, which implemented independent regulation of each stage, resulting in enhanced CO2 capture performance and reduction of CO2 regeneration duty. The MSC absorber was designed with four stages from bottom to top, each serving distinct functions, including CO2 enrichment, CO2 main absorption, CO2 capture efficiency enhancement and aerosol capture. Simulation of the MSC process achieved a rich ethanolamine (MEA) solvent CO2 loading of 0.512–0.570 mol CO2/mol amine, which was 8.1 %–9.9 % higher than typical process. The effects of test duration, amine solution flow rates, reaction temperatures and inlet CO2 concentrations on CO2 absorption performance were studied using the MSC experimental platform. The CO2 regeneration duty reduced by over 13.2 % of the MSC process compared to a typical process using 25 wt% MEA solution and by over 22.9 % using piperazine (PZ)/N-methyldiethanolamine (MDEA) solution. Furthermore, the utilization of NH3/K2CO3 solution achieved an energy consumption reduction of over 41.7 %, resulting in a CO2 regeneration duty as low as 2.02 GJ/t CO2 (1.84 GJ/t CO2, subtracting the heat loss). Meanwhile, potential strategies for optimizing parameters of MSC process were proposed to address the complex and volatile conditions.

Development of dual-functionalized ionic liquids for biphasic solvents: Enhancing the CO2 absorption through two-stage reaction and promoting the energy-saving regeneration

A dual-functionalized ionic liquid was synthesized by facile neutralizing routes from Diethylenetriamine (DETA) and lysine (Lys), which was designated as [DETA]Lys. It could absorb CO2 through a two-stage reaction, achieving a CO2 capacity of up to 2.16 mol CO2/mol ILs. And N-methyl-2-pyrrolidone (NMP) was validated as a good phase splitting agent for [DETA]Lys-based biphasic solvent by tailoring the polarity and hydrogen bonding effect. Thus, DETA-carbamate, Lys-carbamate, and HCO3−/CO32− were formed during CO2 absorption and gathered in the lower layer, while most of the NMP stayed in the upper layer. Finally, the CO2-rich phase took up 53.84 % of the total volume and 99.03 % of the captured CO2, exhibiting a CO2 loading of 4.78 mol CO2/L. The significantly enhanced CO2 loading (4.78 mol/L), decreased stripping volume (53.84 %), and reduced desorption energy (1.28 GJ/ton CO2) allowed for a great reduction in regeneration energy to 1.89 GJ/ton CO2, which was merely 47.37 % of 5 M MEA (3.80 GJ/ton CO2). The regeneration efficiency of the solvent remained at 91.5 % after the 3rd absorption/desorption cycle. Furthermore, the corrosion speeds of the rich and lean phases were merely 0.18 % and 12.35 % of 5 M MEA. The excellent CO2 capture performance and good energy-saving potential enabled the [DETA]Lys + NMP + H2O system an effective absorbent for carbon capture.

A bistable point absorber wave energy convertor with a mechanical motion rectifier

The design of novel wave energy converters (WECs) with the capability of low frequency energy capture is of great significance for the development of low frequency ocean wave energy. In this study, a novel point absorber WEC combined with a bistable mechanism and a mechanical motion rectifier (MMR) is proposed to achieve the goal of efficiently capturing wave energy in the low frequency range. In the WEC, the introduction of a rack-pinion-lever-spring (RPLS) bistable mechanism can not only enhance the capture efficiency in a low frequency range but also protect the system from excessive vibration amplitude through the nonlinear stiffness. Besides, one MMR based power take off (PTO) system is proposed to convert the bidirectional vibration into unidirectional rotation of the generator and extract more power via the mechanism of two one-way pinions. The dynamic model in the time domain for the nonlinear point absorber WEC with the RPLS bistable mechanism and the MMR based PTO system is established in which the convolution term is replaced by the state space method. The characteristics of the nonlinear dynamics and wave energy capture performance for the novel WEC are analysed in regular wave condition. The numerical results demonstrate that the peak capture width ratio of the proposed WEC can reach almost 2 times that of the traditional linear system in a lower frequency range.

Comparative study on the capture performance of two wave energy converters integrated into the jacket-frame foundation

The global pursuit of clean energy resources to cope with escalating energy demands has underscored the pivotal roles of wind and wave power as two prominent renewable energy sources for the power industry. In order to promote the comprehensive harnessing of ocean energy, research efforts have increasingly focused on hybrid approaches, aiming to concurrently capture wind and wave energies. This paper proposes two types of wind-wave hybrid device, which combines wind turbine with a wave energy converter (WEC), based on jacket-frame foundation. The numerical models of the WECs were created using SOLIDWORKS, and the subsequent simulations were conducted using ANSYS Workbench. The comparative analysis revealed that the heave-type WEC had less added mass and radiation damping, coupled with larger response amplitude operator (RAO) and shorter natural period compared to the swinging counterpart. Meanwhile, the swing-type WEC exhibited higher motion speed and greater support reaction force and connecting force, thereby exerting more pronounced influence on the foundation. However, the average hourly power generation of the swinging WEC was significantly better in terms of power capture. In practice, the choice between these WEC configurations should consider aligning the power matrix with the probability distribution of prevailing sea state conditions.

Synthesis of electron-rich benzbisimidazole-containing amorphous poly(Schiff-base) networks for efficient iodine capture

In this work, two benzbisimidazole-containing amorphous poly(Schiff-base) networks (namely ATA-BA and ATA-BZ) are synthesized by reacting benzbisimidazole-containing aromatic tetra-aldehyde building block (ATA) with benzene-1,4-diamine and benzidine, respectively, under solvothermal conditions. The resultant ATA-BA and ATA-BZ networks possess the specific surface areas of 113 and 87 m2/g, respectively. Owing to the presence of abundant imine bond, alkyl-substituted imidazole ring, and extended π-conjugated system, ATA-BA network can effectively capture iodine in both vapor and solution phases with the capture capacities up to 5.29 g g−1 and 2343 mg g−1, respectively, although its specific surface area is not high. The exceptional iodine capture performance of ATA-BA network can be attributed to the strong charge-transfer interactions between imine bond/imidazole ring/π-conjugated system and iodine molecules, as demonstrated by spectroscopic analysis and density functional theory (DFT) calculations. In addition, the iodine capture by ATA-BA network in cyclohexane solution is systematically investigated. The experimental results indicate that the iodine adsorption kinetics and capture behavior obey pseudo-second-order model and Freundlich isotherm model, respectively.

Impact of annealing process on the properties of 0.85Pb(Sc0.5Ta0.5)O3-0.15PbTiO3 ceramics

We have synthesized a ceramic sample 0.85Pb(Sc0.5Ta0.5)O3-0.15PbTiO3 [0.85PST-0.15PT] of perovskite structure by using a conventional solid-state reaction method. Systematic impact of annealing time (AT) is studied methodically for comprehending the ferroelectric and dielectric properties, as well as electrocaloric effect and energy harvesting performance. After 40 h of AT and using the electric field of 40 kV/cm on 0.85PST-0.15PT, we have achieved maximum ferroelectric polarization (P = 46.9 μC/cm2), energy capture performance (W = 0.542 J/cm3), and large positive electrocaloric effect (ΔT ∼ 1.63 K and ΔS ∼ 1.23 J/(K.kg)). Additionally, we also achieved high dielectric constant (ε = 23,350) and low dielectric loss (tanδ = 0.039) at the frequency of 1 Hz. As compared to an unannealed situation, the results on ceramic sample with 40 h of AT have revealed increase in P, ε, ΔT, ΔS, and W by 36%, 27%, 37%, 12% and 14%, respectively. Optimal values of AT differed radically for achieving the highest performance in each category. The best performance of energy storage (Wenergy ∼ 0.638 J/cm3) and energy loss (Wloss ∼ 0.498 J/cm3) densities are achieved with the AT of 30 h. The performance of 0.85PST-0.15PT sample increased gradually with the increase of AT until it attained the highest value and then decreased by further increasing AT – exhibiting a peak distribution. Our investigations have provided valuable insights of optimizing the performance of 0.85PST-0.15PT ceramic system through annealing.

Insights into amine-resin matching strategy for CO2 capture: Adsorption performance tests and Mechanistic investigation

The solid amine adsorbents are potential candidates as materials for post-combustion capture technologies. The type of organic amine and porous material are the key factors influencing the amine-based solid adsorbent performance. Furthermore, there has been relatively little research on the matching mechanism between organic amines and porous materials. This study aims to investigate the effect of the degree of matching between different organic amines and porous materials (X-5 resin) on the performance of CO2 capture. The results indicated that 30 wt% TETA was the highest matching degree with X-5 and had the maximum CO2 adsorption of 205.48 mg/g at 30 ℃. The matching degree between the four amines and the X-5 resin followed TETA > TEPA > PEHA > PEI. Since TETA has the simplest molecular structure, it can be conveniently dispersed in the X-5 pores, which not only significantly improves the utilization of active sites but also prevents the phenomena of agglomeration or sintering. Meanwhile, X-5-30TETA has the highest adsorption energy Eads (−85.22 kJ/mol) and the smallest spatial potential resistance, decreasing the mass transfer resistance effectively, thus further increasing the adsorption capacity. Furthermore, the adsorption kinetics results showed that the Avrami model can relatively accurately predict the experimental results of X-5-TPHI CO2 adsorption. Finally, the in situ DRIFTS indicated that the CO2 adsorption reaction over X-5-30TETA followed predominantly an amphipathic centipede mechanism. This work provides a new idea for the investigation of the matching mechanism between organic amines and porous materials.

Transformation from Knudsen diffusion to facilitated diffusion for CO2 in confined mass transfer channels of polyimide mixed matrix membranes

Incorporation of porous materials in a polymeric membrane is an effective strategy for improving the gas permeability of the resulting mixed matrix membranes (MMMs). However, effective improvement of selectivity of membrane toward CO2 separation is still a significant challenge due to the insufficient CO2 capture performance of porous materials. In this study, polyimide (PI)-based MMMs with enhanced CO2 capture performance were prepared for CO2 separation. First, an ionic liquid (IL) with a high affinity for CO2 was immobilized in the inner pore structures of two types of mesoporous silica (SiO2) molecules to form IL@SiO2 composites. These composites were used as nanofillers to construct the MMMs. The stable immobilization of IL inside the pores of the mesoporous SiO2 indicated that the IL@SiO2 and MMMs both exhibited higher adsorption selectivity for CO2. The gas solubility coefficient of the MMMs was positively proportional to their maximum gas adsorption capacity, which was determined by the gas adsorption capacity of the PI polymer and nanofillers. More interestingly, the diffusion coefficients of different gases in the MMMs were closely related to the confined mass transfer channels introduced by the nanofillers. The diffusion of CO2 in the confined mass transfer channels of MMMs was facilitated and N2 diffusion was slightly inhibited, which increased the diffusion selectivity of the resulting MMMs for CO2. Combined with Maxwell–Wagner–Sillar model calculations for gas permeation, it was confirmed that IL immobilization transformed the diffusion mode of CO2 in the confined mass transfer channels of the MMMs from Knudsen diffusion to facilitated diffusion. However, the immobilization of excessive ILs in the mesopores blocked the mass transfer channels of the MMMs, resulting in lower gas permeability and decreased CO2 separation selectivity.

A novel on-site SMR process integrated with a hollow fiber membrane module for efficient blue hydrogen production: Modeling, validation, and techno-economic analysis

Steam methane reforming (SMR) is widely used in the hydrogen production industry; however, a significant amount of CO2 is released during this process. Several efforts have been made to produce low-CO2 hydrogen (blue hydrogen) via SMR; however, the proposed solutions are not applicable to small-scale plants. Therefore, this study proposes an on-site SMR process combined with a hollow fiber membrane module (HFMM) for CO2 capture in small-scale plants. First, mathematical models for the on-site SMR process and HFMMs were developed, and their accuracy was validated with real-world data. Second, we designed and implemented the SMR–HFMM model based on different operating conditions and gas compositions at three potential CO2 capture locations (dry syngas, PSA tail gas, and flue gas). The CO2 capture performances at these three locations were compared using five performance indicators: stage cut, separation factor, CO2 recovery rate, permeate composition, and retentate composition. Finally, to evaluate the integrated processes for each CO2 capture location, feasible ranges of the number of HFMMs and the levelized cost of hydrogen (LCOH) were calculated. In the case of CO2 captured in dry syngas, the number of HFMMs required to achieve a CO2 purity of over 90% was calculated to be 10–25. Furthermore, despite additional HFMM installation, the LCOH was 0.8%–1.5% lower than that of the conventional on-site SMR process that is 7.07–7.13 USD/kgH2. The proposed integrated SMR–HFMM process is a potential solution to the problem of CO2 emissions in on-site SMR processes with a lower LCOH. Therefore, the findings of this study could be of significant importance in improving the environmental sustainability of hydrogen production in small-scale plants.

Postsynthetic amine modification of porous organic polymers for CO2 capture and separation

AbstractPorous organic polymers (POPs) constitute an important class of sorbents studied in various adsorption and separation processes. Their unique properties, including high surface areas, adjustable pore sizes, and surface chemistries make them ideal candidates for CO2 capture. To achieve a high CO2 adsorption capacity and selectivity, particularly at the low partition pressures required for post‐combustion CO2 capture or direct capture of CO2 from the atmosphere, incorporating amines onto the polymer frameworks or within the pores has shown much promise. This review provides a comprehensive summary of recent studies on the synthesis and CO2 capture performance of amine‐functionalized POPs. The review also provides a detailed discussion of structure‐performance relationships, focusing on how the loading amount and amine type influence CO2 capture capacity, CO2/N2 selectivity, heat of adsorption, sorption kinetics, and recyclability of POPs. Additionally, the authors offer their perspective on the challenges associated with the practical implementation of amine‐modified POPs for CO2 capture.

An investigation on the effects of organic additives on CO2 capture performance of Na2CO3 solution

AbstractBACKGROUNDThe large‐scale practical application of CO2 capture using carbonate solutions is mainly limited by their low CO2 absorption rate. In view of this, it is feasible to improve CO2 capture performance of carbonate solution by adding additives. In this paper, low‐cost sodium carbonate (Na2CO3) solution was selected as the main CO2 absorbent, and the effects of different organic additives on CO2 capture performance of Na2CO3 solutions were systematically investigated.RESULTSThe results showed that 0.04 mol/L tetrabutylammonium bromide (TBAB) could achieve a better enhancement effect on CO2 capture performance of Na2CO3 solution. After addition of TBAB, the maximum CO2 absorption rate of Na2CO3 solution was improved to 2.52 × 10−3 mol/min, which increased by 105%. And the maximum CO2 desorption rate could also be improved by 45%. TBAB/Na2CO3 system not only realized a high CO2 absorption capacity of 0.769 mol/mol, but also maintained 82% of the initial CO2 absorption capacity after three cyclic tests. The regeneration heat duty of TBAB/Na2CO3 solution was calculated to be 1136.6 kJ/mol, which was significantly lower than that of single Na2CO3 solution and conventional MEA aqueous solution. The promotion mechanism of TBAB in Na2CO3 solution was explored using Fourier transform infrared spectra (FTIR) and 13C nuclear magnetic resonance (NMR) analysis.CONCLUSIONThe introduction of TBAB additive could significantly improve CO2 capture performance of Na2CO3 solution and reduce regeneration heat duty, making it a possible option in the field of post‐combustion CO2 capture. © 2023 Society of Chemical Industry (SCI).

Hierarchical Ti3C2/CdIn2S4 micro-flower facilitates enhanced tetracycline degradation and Cr(VI) reduction

Developing of a photocatalyst for the degradation and reduction of high concentrated pollutants from wastewater is of great importance. 2D/2D flower-like Ti3C2/CdIn2S4 (MXCIS) was successfully prepared by integrating Ti3C2 and CdIn2S4 using a hydrothermal method. MXCIS-8 possess the best photocatalytic activity, and its removal efficiency of 50 mg/L of TC and Cr (VI) can reach 80.4% and 60.8%, respectively. This is caused by the Schottky heterostructure with the well 2D/2D interface, which can boost its photon capture performance and effectively hinder the recombination of photo-generated electrons and holes. Hydroxyl radicals, superoxide radicals, and h+ participate in the TC degradation, and both acidic and alkaline conditions are conducive to enhancing the degradation activity of MXCIS-8. However, only e− is the main contributor to the Cr(VI) reduction, and the photocatalytic performance of MXCIS-8 decreases under alkaline conditions. Importantly, MXCIS-8 exhibits satisfactory physicochemical stability, recyclability, and environmental friendliness. Overall, this work confirms that MXCIS has broad application potential in the removal of Cr (VI) and TC pollutants in wastewater treatment.

Efficient capture of uranium by polydopamine functionalized MgO@Bi2O3 composite from aqueous solution

A series of polydopamine (PDA) modified MgO@Bi2O3 composites (MB/PDA) with different mass ratios were fabricated to remove soluble U(VI). Batch experiments showed that MB/PDA-2 was provided with better adsorption performance than MB/PDA-1 and MB/PDA-3 and the maximum adsorption amount (C0 = 10 mg/L, m/v = 0.1 g/L, pH = 4.0 and T = 298 K) reached 465.8 mg/g within 80 min. Moreover, over 95% U(VI) was removed by MB/PDA-2 in the process of dynamic adsorption and MB/PDA-2 still displayed high adsorption percentage (75%) after five cycles. The electrostatic attraction, complexation, redox reaction and cation-π interaction apparently influenced the U(VI) capture performance on MB/PDA-2. In short, MB/PDA-2 with high adsorption capacity was a preeminent material to extract soluble U(VI).

Effect of the number of magnetic matrices on particle capture in high gradient magnetic separation

A comprehensive understanding of the capture process involving matrices in high gradient magnetic separation (HGMS) is crucial for the design and improvement of matrix performance. However, few existing studies have paid attention to the influence of the number of magnetic matrices on the capture process. In this work, we numerically investigate this issue in both longitudinal and transversal HGMS systems, where multiple scenarios with different particle sizes, flow rates and matrix spacing are considered. Interestingly, we show that in most cases, increasing the number of magnetic matrices along the flow direction has little to no influence on the capture radius. It has a certain effect on improving the capture radius only in a few specific cases, such as when dealing with large particles at low flow rates with closely spaced matrices or when working with small particles at high flow rates with widely spaced matrices. These phenomena are related to the appearance of repulsive magnetic forces around matrices and the distribution characteristics of magnetic forces. The obtained results indicate that, in the design of the practical HGMS system, simply increasing the number of matrices along the flow direction may not be a reasonable or effective strategy for enhancing capture performance.

Coal fly ash-bound limestone-derived sorbent pellets for high-temperature CO2 capture

Poor CO2 capture stability and serious elutriation are the issues commonly occur when limestone circulating in the fluidized bed-based Calcium Looping (CaL) system. Hence, three types of coal fly ash-bound (CFA-bound) limestone-derived sorbents were synthesized via mixing the limestone, calcined lime and hydrated lime with coal fly ash, respectively. The generated ternary Ca-Al-O and Ca-Si-O phases offer structural stability for CFA-bound limestone-derived sorbents and improve their cyclic CO2 capture performance. Moreover, extrusion-spheronization method was adopted to produce CFA-bound limestone and hydrated lime sorbent pellets to synergistically enhance cyclic CO2 capture capability and mechanical properties. It is found that hydrated lime is superior to limestone as the calcium precursor to prepare CaO-based sorbent pellets due to its desirable pore structure and high binding force. Therefore, the CFA-bound hydrated lime pellets containing 15 wt % of fly ash (HL/CFA15-P) exhibits a high carbonation conversion of 40 % after 17 cycles, which is nearly 1.4 times that of limestone pellets. The discrepancy on carbonation conversion between the two sorbent pellets is enlarged to ∼1.6 times after 100 cycles, which is calculated using a semi-empirical equation. Moreover, HL/CFA15-P exhibits outstanding mechanical property, whose compressive strength reaches 6±1.7 MPa, which is comparable to the cement-bound CaO-based sorbent pellets.

Novel biphasic solvent based on 2MPRZ absorbent for post-combustion CO2 capture with low viscosity, superior phase-splitting behavior and low energy consumption

The CO2 phase change absorbents(CPCAs) formed by introducing phase-splitting agents have attracted increasing attention because of their great energy-saving potential. However, the volatilization problem of the phase-splitting agents and the high viscosity of the solution affect the application of CPCAs. In this work, a novel CPCAs based on 2-Methylpiperazine (2MPRZ)/H2O was established by introducing triethylene glycol monobutyl ether (TGBE) with a high boiling point as a phase-splitting agent, and the 2MPRZ/H2O/TGBE system exhibited low volatility and low viscosity. The CO2 capture performance of the novel CPCAs with different ratios was investigated in this work. The best CO2 absorption rate was achieved by 2.5 M 2MPRZ/H2O/TGBE. The viscosity of this system before and after the CO2 absorption process was merely 7.68 mPa·s and 11.64 mPa·s, respectively, and no volatilization of the phase-splitting agent was observed simultaneously. A convenient and rapid titration method was employed to determine the distribution of the 2MPRZ products in the two phases, which showed that 98 % of the 2MPRZ products were located in the CO2-rich phase. In addition, the CO2-rich phase captured 99 % of the total CO2, indicating that this system has superior phase-splitting behaviors. The regeneration energy consumption of this biphasic absorbent was 2.59 GJ/t CO2, which was 32.6 % lower than that of traditional MEA. Furthermore, the salting-out effect was proved to be the cause of the phase-splitting behavior by 13C NMR analysis.

Wave energy conversion using heaving oscillator inside ship: Conceptual design, mathematical model and parametric study

A concept of utilizing heaving oscillators inside a ship as a means of capturing wave energy is proposed, drawing inspiration from the two-body self-contained wave energy point absorber. This concept involves the ship acting as a small-amplitude-motion platform and the heaving oscillator as a large-stroke body, where the kinetic energy of their relative motion can be converted into electrical energy through a power take-off (PTO) system. The dynamic equations of the ship and the inboard heaving oscillator under regular waves are derived using the boundary element method and solved using a Python code with 4th-order Runge-Kutta integration. The numerical results exhibit favorable agreement with publicly available experimental data. Furthermore, the effects of forward speed, encounter angle, and PTO mechanical parameters on various aspects, including ship motion, oscillator response, wave energy capture performance, and inner loads, are investigated. The results show that the concept of heaving oscillator inside ship has no significantly adverse effects on the ship seakeeping performance. Both forward speed and encounter angle significantly influence the encounter period and thereby impact the sensitivity of capture width (CW) at a broader band of incident wave periods. Conversely, PTO mechanical parameters exerting a more localized impact primarily under long incident waves.

Investigation on Integrated CO2 Capture and Conversion Performance of Ni-CaO Dual-Function Materials Pellets: Effect of Ni Loading and Optimization of Operating Parameters

Investigation on Integrated CO₂ Capture and Conversion Performance of Ni-CaO Dual-Function Materials Pellets: Effect of Ni Loading and Optimization of Operating Parameters

Performance improvement of Na4SiO4 doped with Li2CO3-K2CO3 for high-temperature CO2 capture and thermochemical energy storage

Na4SiO4 is regarded as a new candidate of high-temperature CO2 sorbent. However, the sorption/desorption temperature of Na4SiO4 is high, and cyclic sorption capacity is low. In this study, Na4SiO4 sorbents doped with Li2CO3-K2CO3 (LiKCO3) were synthesized, and the dynamic, isothermal, and cyclic CO2 capture performances were investigated to improve the performance. The maximum CO2 sorption capacity of Na4SiO4-20LiKCO3 reached 20.64 wt% at 725 °C, and the cyclic sorption capacity was about 50 % higher than that of pure Na4SiO4. The results indicated that LiKCO3 doping could efficiently decrease the optimal sorption/desorption temperature of Na4SiO4. Furthermore, the maximum conversion efficiency and energy storage density of Na4SiO4-20LiKCO3 reached high levels of 95.7 % and 788 kJ/kg, respectively. Finally, the CO2 chemisorption mechanisms on the Na4SiO4 and Na4SiO4-LiKCO3 co-adsorption surfaces were studied via density functional theory calculations. LiKCO3 doping could enhance CO2 adsorption energy and C–OS covalent interaction on the sorbent surface and the energy levels of the CO2/Na4SiO4-LiKCO3 system were reduced. These changes were beneficial to CO2 chemisorption and agreed well with the experimental values. Thus, Na4SiO4 doped with LiKCO3 had high potential for high-temperature CO2 capture and thermochemical energy storage.