Performance Of CO2 Capture Research Articles

Performance of a novel waste heat-powered ionic liquid-based CO2 capture and liquefaction system for large-scale shipping

In this work, we proposed a novel CO2 capture and liquefaction system for large-scale shipping using ionic liquid as capture solvent. By utilizing the waste heat of the exhaust gas and jacket cooling water from the ship’s engine as well as the residual pressure energy of the N2-O2 mixture from the CO2 absorption and desorption process, the system’s net energy consumption has been significantly reduced. We established the thermodynamic model of the system and investigated the effect of 10 primary system operational parameters on system performance with 3 different ionic liquids as CO2 capture solvent. The results demonstrated that the system with [DEME][TF2N] as the CO2 capture solvent had the best system performance. In addition, we performed a multi-parameter optimization of the system using simulated annealing algorithm with net energy consumption as the optimization objective and the minimal net energy consumption is 0.467 GJ/tCO2. Compared to the CO2 capture system that do not utilize waste heat and residual pressure energy, the net energy consumption was reduced by 57.29 % under optimal operational conditions which proves that the novel system significantly reduces the energy consumption of the CO2 capture and liquefaction process.

Carbon capture via electrochemically mediated alkaline absorption: Lab-scale continuous operation

Energy-efficient capture technologies need to be deployed by 2050 to abate global warming caused by excessive carbon dioxide (CO2) emissions. CO2 capture using alkaline solutions and absorbent regeneration mediated through bipolar membrane electrodialysis (BMED) have been tested previously as a standalone technology. However, the continuous operation of an integrated system remains largely unclear. Here, a bench-scale study was conducted using an integrated prototype to analyze the performance of CO2 capture and electrochemical regeneration using potassium hydroxide (KOH) aqueous solution. A wide range of current densities from 150 to 1000 A/m2 was applied to demonstrate the continuous operation of the CO2 capture system emphasizing the stability in attainable high rich carbon loading and CO2 desorption. The electrochemical regeneration module achieved CO2 desorption efficiency of 70% and absorbent recovery up to 89% under industrial relevant current densities of 500–1000 A/m2. The absorbent recovery has been identified to be a result of the combined effect of load ratio and rich carbon loading. The observed inefficient CO2 separation indicates significant potential to enhance energy efficiency. These results represent a pivotal step forward in electrochemically mediated CO2 capture technology, with promising potential for rapid industrial scale-up in the near future.

Molecular dynamics simulation and experimental verification of a biphasic solvent for CO2 capture

In the context of solvent-based carbon capture, researchers and industries are often interested in improvements in the efficiency of CO2 capture along with the reduction in the required energy. This study employs molecular dynamics (MD) simulation based on a reax force field and experimental investigation to study the effects and main mechanisms of a mutual amine absorbent including diethylenetriamine (DETA) and diethylethanolamine (DEEA), accompanied by NMP and water co-solvents, on the performance of CO2 capture in a phase change system. The implementation of time-dependent partial radial distribution functions (TD-PRDF, gαβrtm) and coordination number (CN) analyses revealed the significant formation of C-N bonds between carbon (C) derived from CO2 and nitrogen (N) within the solution. The direct relationship between changes in DETA molar ratios and CO2 loading, coupled with examining the catalytic role of DEEA in facilitating CO2 removal through protonation, has been thoroughly studied with MD. The experimental methodology was followed to validate the MD results. The optimum composition, DETA: DEEA: NMP with a molar ratio of 3:2.5:1, as determined through MD simulations exhibitsgαβr|tm = 9.848, CN=0.403 at tm= 1 ns. The stable C-N absorption bond length is calculated to be between 1.7 and 1.77 Å. Experimental results confirm a CO2 loading capacity of 0.93 mol/mol for this composition.

Exceptional indoor carbon capture using epoxide-modified polyamine functionalized materials

In addressing concerns related to symptoms like dizziness, nausea, and reduced productivity stemming from elevated indoor CO2 levels, the primary objective of the current CO2 adsorption technology is to enhance the adsorption capacity. However, the stability and applicability of the adsorbent are of greater importance in indoor carbon capture than in other settings. This study examines the performance and stability of indoor CO2 capture using propylene oxide-modified tetraethylenepentamine supported on novel super carbon, gas-phase hydrophilic silica dioxide, and graphitic phase carbon nitride carriers. The corresponding painted films were developed to facilitate the application in indoor CO2 capture. Thermogravimetric analysis demonstrates that the propylene oxide-modified materials are more stable than the unmodified compositions. The findings indicate that an optimal adsorption capacity is achieved when water is used as the solvent and carboxymethyl cellulose sodium as a dispersant, while maintaining a carrier-to-tetraethylenepentamine mass ratio of 1:0.75. Furthermore, the painted films are stably formed by using isopropanol instead of water, and the tetraethylenepentamine-to-propylene oxide molar ratio of 1:2 for super carbon and graphitic phase carbon nitride as carriers, which exhibit notable enhancements in adsorption performance by 160.0 % and 41.8 %, respectively. The film using super carbon as supporter exhibited the highest adsorption capacity of 122.83 mg/g. This suggests that the compositions are more readily available for indoor CO2 capture by coating in everyday scenarios. Notably, even after undergoing five adsorption–desorption cycles, the desorption efficiency of the solid amine adsorbent remains consistently above 95 %.

CO2 capture performance, kinetic and corrosion characteristics study of CO2 capture by blended amine aqueous solutions based on 1-(2-hydroxyethyl) piperidine

The chemical absorption method using amine-based aqueous solutions as absorbents is considered a critical technology in the mitigation of CO2 emissions. However, the trade-off between absorption performance and energy consumption presents a significant challenge for large-scale industrial applications. In this study, we propose using N-(2-hydroxyethyl)ethylenediamine (AEEA), 1-(2-amino Ethyl)piperazine (AEP) and piperazine (PZ) to regulate the CO2 capture characteristics of 1-(2-hydroxyethyl)piperidine (HEP) aqueous solution. We found that the addition of promoter AEEA/AEP/PZ increases the CO2 absorption and desorption performance of HEP aqueous solution. We established the CO2 capture mechanism, which involves the generation of HEPH+, carbamate, and bicarbonate during the absorption of CO2. During the desorption process, the bicarbonate can be decomposed, while the carbamate remains in the solution. Furthermore, we obtained data on the kinetics and corrosion characteristics of the blended absorbents. The absorption resistance of the three blended amine aqueous solutions is concentrated on the gas film, accounting for approximately 77 %. The corrosion rate of blended amine-enriched solutions on 20# carbon steel decreases with the increasing mass fraction of promoters or CO2 loading. SEM-EDS analysis revealed the presence of a dense FeCO3 oxide film on the surface of 20# carbon steel, which protects the carbon steel sheet from further corrosion. Overall, the proposed absorbents indicated a promising potential in the CO2 capture applications.

Advanced process integration and machine learning-based optimization to enhance techno-economic-environmental performance of CO2 capture and conversion to methanol

Developing economically sustainable CO2 capture and conversion processes is essential to realize carbon neutrality. This study proposed an integrated process for CO2 capture and conversion-to-methanol (CCTM) and applied machine learning-based optimization to enhance techno-economic-environmental performance. After validating CO2 capture and CO2-to-methanol sections, an advanced CCTM design was developed and compared with conventional one regarding techno-economic-environmental performance across various operating scenarios. The advanced CCTM exhibited significant improvements in energy consumption (14.73–16.30%), production cost (0.81–1.28%), and net CO2 reduction (3.13–3.38%) owing to efficiently reusing waste heat, off-gas, and water resources. The one-at-a-time sensitivity analysis revealed roles of each variable and nonlinear variable-performance tendencies among operating variables in the advanced CCTM process. Subsequently, a well-developed deep neural network (DNN) model precisely formulated the relationship between key variables and performances. The DNN-based optimization provided optimum operating conditions within a minute, resulting in an 8.21 $/tMeOH (∼0.81%) reduction in production cost compared to base case of CCTM. Notably, the total CO2 capture rate of 92.53% at an optimal condition highlighted the significant contribution of advanced CCTM to carbon neutrality. The findings provide a viable reference for the effective and sustainable design and operation of an integrated CCTM process.

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.

Piperazine-impregnated silica aerogel for direct air capture of CO2 for prevention of urea formation

Direct air capture (DAC) of CO2 using solid sorbents is a promising negative emission technology to reduce global greenhouse gas emissions. Despite many advantages of alkyl-amine-based adsorbents, degradation caused by urea formation under a dry CO2 regeneration remains a challenge. Herein, we hypothesized that certain nitrogen-containing heterocyclic compounds can contribute toward suppressing urea formation by the ring structure and thus, selected piperazine (PZ) as a representative chemical. PZ was wet-impregnated onto a silica aerogel (PZ/silica) with controlled pore size and volume. The synthesized sorbents exhibited high CO2 sorption uptake and kinetics. In a cyclic test via temperature swing adsorption (adsorption: calibrated 200 ppm CO2; desorption: dry CO2), PZ/silica exhibited stable and high adsorption capacities (average 1.3 mmol/g over 24 cycles). The suppression of urea formation in PZ/silica under extended dry CO2 regeneration was demonstrated using an in-situ diffuse reflectance infrared Fourier transform spectroscopy, thereby proving the above hypothesis. PZ/silica showed good anti-oxidation performance of CO2 capture, 1.6 mmol CO2/g, after 12 h oxidation under 21% O2 balanced with N2. Besides, PZ/silica maintained a CO2 adsorption uptake of 0.79 mmol/g after the preliminary adsorption of H2O. This study proposes a novel way to synthesize DAC solid adsorbents using N-containing heterocyclic compounds.

MOF-derived nano CaO for highly efficient CO2 fast adsorption

Calcium looping is considered to be one of the best approaches for industrial CO2 high-temperature capture, whereas current CaO-based sorbent suffers poor cyclic performance, especially the relations between precursor structure and CO2 fast adsorption capacity still need to be further revealed. In this work, three calcium-based metal frameworks (Ca-MOFs) with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. It was found that LAC MOF-derived CaO achieved a fast adsorption capacity of 11.8 mmol g−1 (78 % of total adsorption) after 4 cycles. This was because the fiber bundle-like original LAC MOF structure changed gradually to nanosheets after 600 °C pyrolysis and finally formed regular CaO spheres with an average size of 100 nm after an 800 °C -calcination, thereby preventing further aggregation of CaO particles during the thermal transition process. In addition, the adsorption performance did not rely on pore structure, and thus pore-blocking showed little influence on the performance of CO2 capture. Hence, high stability can be achieved simply by avoiding particle sintering. The systematic study marks the significance of precise tailoring of nano-CaO for achieving the desired performance of CO2 fast adsorption.

Modeling of pre-combustion carbon capture with CO2-selective polymer membranes

CO2-selective polymer membranes were recently applied to pilot-scale and bench-scale pre-combustion capture and the obtained CO2 capture ratios were reported to be less than 90%, which limits their application in industrial processes such as IGCC plants. This work is aimed to explore the possibility of achieving a CO2 capture ratio >95% and CO2 purity >95% in a gas-separation unit equipped with currently-available CO2-selective polymer membranes. A mathematical model for single-stage membrane gas separation was developed, and the effect of membrane characteristics (permeance and selectivity), as well as the operating parameters such as feed and permeate pressure, and feed flow rate on the performance of CO2 capture was investigated. The simulation results reveal the optimal conditions that are necessary for a high-performance CO2 capture process using the real industrial syngas and highlight the potential of facilitated transport membranes for CO2 removal in both the oxygen-blown and air-blown IGCC processes.

One-step approach to Quaternary (B, N, P, S)-Doped hierarchical porous carbon derived from Quercus Brantii for highly selective and efficient CO2 Capture: A combined experimental and extensive DFT study

Recently, the enhancement of atmospheric carbon dioxide (CO2) concentration has a negative impact on the environment and human health. Adsorption is well recognized as a promising technology to control CO2 emission in which the design of an optimum adsorbent is one of the most critical challenges. In this article, multi-heteroatoms doped porous carbons have been successfully derived from Quercus Brantii by one-step doping–activation to investigate the textural characteristics and heteroatoms doping effects on CO2 capture application. Based on the physicochemical properties of the adsorbents, which were characterized using varied techniques (FE-SEM, EDS, HR-TEM, XRD, FT-IR, XPS, BET, and BJH), the introduction of heteroatoms provides more active sites in carbon networks and develops the porous architecture of each activated carbon, resulting in diverse CO2 capture performances. The low content of phosphorus (P) incorporated in P-doped activated carbon (PAC) perfected the performance of CO2 capture to reach a high uptake (7.13 mmol g−1 at 1 bar and 20 °C) on a heterogeneous surface. Apart from the high equilibrium and dynamic CO2 uptake, these Quercus Brantii-based carbonaceous adsorbents present superior CO2 selectivity over N2, CH4, and H2, prominent cyclic regeneration capacity, high turnover frequency (TOF) and turnover number (TON) for commercial scale as well as fast kinetic adsorption. The density functional theory (DFT) method was performed to reveal the adsorption mechanisms as well as electronic properties of the systems.

Study on the performance of CO2 capture from flue gas with ceramic and PTFE membrane contactors

Excessive CO2 emissions contribute to global warming, which may cause potential threat to survival of humans and other creatures, and it is necessary to take effective measures to curb CO2 emissions. Gas-liquid membrane contact CO2 separation technology is an emerging CO2 capture technology that combines advantages of membrane separation and chemical absorption. In this paper, differences of CO2 capture performance between ceramic and polytetrafluoroethylene (PTFE) membranes with pore size of 10 nm and 100 nm are investigated comprehensively. The morphological structure, pore size distribution, wettability and membrane flux of ceramic and PTFE membranes are analyzed by membrane characterization. Moreover, with monoethanolamine (MEA) as absorbent, CO2 capture performance under different operating parameters (e.g., absorber flow rate and temperature, gas flow rate and pressure) is investigated through experiments based on ceramic and PTFE membrane modules. The CO2 capture efficiency of ceramic and PTFE membrane is 94.7% and 99.3%, respectively. However, the mass transfer rate of ceramic membrane is much higher than that of PTFE membrane. The results show that ceramic membrane exhibits favorable CO2 capture performance under appropriate operation parameters. This paper will provide theoretical and technical references for subsequent industrial CO2 capture applications.

Promoted alkanolamine solutions with amino acid L-arginine for post-combustion CO2 capture in a micro-reactor

With the aim of replacing amine solvents, in the current study, the novel mixture solutions were proposed for CO2 absorption combining amino acid (L-Arginine) with primary, secondary, and tertiary alkanolamines. The mass transfer performance of CO2 capture in the aqueous solutions of MEA-ARG, DEA-ARG, and MDEA-ARG was intensified under operational conditions of 4–12 wt% arginine concentration, 120–300 mL/min feed solvent flow rate, 3–9 mL/min inlet gas flow rate. In this regard, a T-shape micro-reactor with a diameter of 800 μ and a length of 29.5 cm was utilized. All the experiments were performed under the atmospheric pressure and absorption temperature of 45 °C. Considering industrial restrictions, the total concentration of mixtures was kept constant at 25 wt% for MEA-ARG, 35 wt% for DEA-ARG, and 50 wt% for MDEA-ARG. The results of CO2 absorption efficiency (ef), overall volumetric mass transfer coefficient, OVGMTC, (KGaV), and volumetric mass transfer flux (NAaV) indicated that in all three cases, the aqueous MEA-ARG solution has the highest value of 96%, 90.95 kmol/m3.h.kPa, and 361.82 kmol/h.m3, respectively. Also, while the gas and liquid flow rates were kept constant in their middle points, adding arginine from 4 to 12 wt% enhanced the values of the ef from 92.55% to 93.76% for DEA-ARG and from 79.20% to 93.23% for MDEA-ARG solutions, respectively. However, the results were obtained differently for solution MEA-ARG.

Technology selection for capturing CO2 from wood pyrolysis

Emerging negative emission technologies (NETs) are considered as effective measures to reduce carbon dioxide emissions to achieve the climate goal set by the Paris Agreement, and bioenergy with carbon capture and storage (BECCS) is one of the most important NETs. Integrating CO2 capture with biomass pyrolysis (PyrCC) is attracting increasing interest, because biomass pyrolysis has been widely used to produce biooil to replace fossil fuel for decarbonizing the transport sector. In order to provide guidance to the selection of CO2 capture technologies, this paper evaluated the technical and economic performances of PyrCC when different CO2 capture technologies are integrated, including monoethanolamine-based chemical absorption (MEA-CA), temperature swing absorption (TSA), calcium looping (CaL), and chemical looping combustion (CLC). Generally speaking, CLC can realize the highest capture amount of CO2 with the lowest energy penalty. Meanwhile, CLC and CaL show the lowest levelized cost of CO2 (LCOC), which are around 56$/tCO2; and on the contrary MEA-CA shows the highest one of 83$/tCO2. In addition, the key process parameter of pyrolysis, reaction time, has clear effects on the performance of CO2 capture as the longer reaction time leads to an increased amount of captured CO2 and reduced energy penalty. As a result, when the reaction time increases, the LCOCs of all assessed technologies decrease. Moreover, the net present value and the payback time are also estimated for different technologies. At the carbon price of 70.1$/tCO2, MEA-CA and CLC show the longest and shortest payback time that are 5.9 years and 3.2 years respectively.

Intrinsic insight of energy-efficiency optimization for CO2 capture by amine-based solvent: effect of mass transfer and solvent regeneration

Here the energy-efficiency performance of CO2 capture is investigated based on the combination of bench-scale experiments and simulated calculation. A comprehensive evaluation is performed by L25(56) orthogonal tests to analyze the effect of crucial operating conditions on CO2 capture. Experiments reveal desorption temperature and flue gas flow play a major role for CO2 capture efficiency. Rising flue gas flow could promote interfacial area, but decreases contact time, overally, net CO2 flow approximately determines the linear relationship of capture efficiency and absorption rate. With combination of Eulerian-Eulerian method with the population balance model, we predict the dynamics evolution process of dispersed bubble, in order to provide the detailed information of interphase contact area and multiphase flow for modelling complete mass transfer parameters. Meanwhile, rigorous process simulation is developed to analyze the energy consumption of carbon capture. Higher desorption temperature provides much leaner solvent, which is beneficial to CO2 absorption, but consumes greater energy penalty.

Preliminary experimental study on the performance of CO2 capture prototype based on temperature swing adsorption (TSA)

Capturing CO2 from the post-combustion flue gas through temperature swing adsorption (TSA) has been considered as an effective solution to reduce carbon emissions. However, in the fixed bed field, the vast majority of the existing experimental studies are bench-scale. In this study, a fixed bed double-column TSA prototype with treatment capacity of 2.4 m3/h flue gas is designed and developed. The influence from parameters, such as desorption duration, adsorption temperature, desorption temperature, CO2 concentration, heat recovery duration and vacuum duration, are analyzed, to the prototype performance, based on the preliminary experiment data. The performance indicators include purity, recovery ratio, productivity, specific energy consumption, coefficient of performance of CO2 capture and exergy efficiency. The prototype performance in single- and double-column modes are compared as well. The results of double-column mode show that decrease of adsorption temperature (from 293 K to 278 K), increase of desorption temperature (from 353 K to 373 K) and CO2 concentration (from 13% to 19%) lead to an improvement of the prototype performance, the maximum purity, recovery and productivity are 98.13%, 81.30% and 25.22 kg/(ton·h), respectively. The maximum coefficient of performance of CO2 capture and exergy efficiency are 2.46 and 17.67%, respectively. Extending the desorption time is conducive to the improvement of the prototype performance, however, a long operation time would be meaningless to improve performance. With the addition of heat recovery, exergy efficiency increases from 12.30% to 12.89%. At the same time, the productivity of double-column is 2.24 times higher than that of single-column.

Tailoring Amine-Functionalized Ti-MOFs via a Mixed Ligands Strategy for High-Efficiency CO2 Capture.

Amine-functionalized metal-organic frameworks (MOFs) are a promising strategy for the high-efficiency capture and separation of CO2. In this work, by tuning the ratio of 1,3,5-benzenetricarboxylic acid (H3BTC) to 5-aminoisophthalic acid (5-NH2-H2IPA), we designed and synthesized a series of amine-functionalized highly stable Ti-based MOFs (named MIP-207-NH2-n, in which n represents 15%, 25%, 50%, 60%, and 100%). The structural analysis shows that the original framework of MIP-207 in the MIP-207-NH2-n (n = 15%, 25%, and 50%) MOFs remains intact when the mole ratio of ligand H3BTC to 5-NH2-H2IPA is less than 1 to 1 in the resulting MOFs. By the introduction of amino groups, MIP-207-NH2-25% demonstrates outstanding CO2 capture performance up to 3.96 and 2.91 mmol g−1, 20.7% and 43.3% higher than those of unmodified MIP-207 at 0 and 25 °C, respectively. Furthermore, the breakthrough experiment indicates that the dynamic CO2 adsorption capacity and CO2/N2 separation factors of MIP-207-NH2-25% are increased by about 25% and 15%, respectively. This work provides an additional strategy to construct amine-functionalized MOFs with the maintenance of the original MOF structure and high performance of CO2 capture and separation.

Multicycle Performance of CaTiO3 Decorated CaO-Based CO2 Adsorbent Prepared by a Versatile Aerosol Assisted Self-Assembly Method.

Calcium oxide (CaO) is a promising adsorbent to separate CO2 from flue gas. However, with cycling of carbonation/decarbonation at high temperature, the serious sintering problem causes its capture capacity to decrease dramatically. A CaTiO3-decorated CaO-based CO2 adsorbent was prepared by a continuous and simple aerosol-assisted self-assembly process in this work. Results indicated that CaTiO3 and CaO formed in the adsorbent, whereas CaO gradually showed a good crystalline structure with increased calcium loading. Owing to the high thermal stability of CaTiO3, it played a role in suppressing the sintering effect and maintaining repeated high-temperature carbonation and decarbonation processes. When the calcium and titanium ratio was 3, the CO2 capture capacity was as large as 7 mmol/g with fast kinetics. After 20 cycles under mild regeneration conditions (700 °C, N2), the performance of CO2 capture of CaTiO3-decorated CaO-based adsorbent nearly unchanged. Even after 10 cycles under severe regeneration conditions (920 °C, CO2), the performance of CO2 capture still remained nearly 70% compared to the first cycle. The addition of CaTiO3 induced good and firm CaO dispersion on its surface. Excellent kinetics and stability were evident.

Self-templating synthesis of nitrogen-rich porous carbons using pyridyl functionalized conjugated microporous polytriphenylamine for electrochemical energy storage

Porous carbon materials are important in electrochemical applications due to their unique nanostructures and remarkable physicochemical stability. In this work, nitrogen-doped porous carbons were fabricated using the self-templating networks of pyridyl conjugated microporous polytriphenylamine. The prepared nitrogen-doped porous carbons show a high content of nitrogen (4.6–11.5 wt%) with fine performance of CO2 capture (store 14.0–17.0 wt% at 273 K and 1 bar) and high specific surface area up to 1059 m2 g−1 that surpasses materials prepared using other polymer networks. More importantly, the nitrogen-doped porous carbons exhibit great potentialities as electrode materials of supercapacitors with a specific capacitance of up to 238 F g−1 at 0.5 A g−1 that retained almost 100% after 1000 cycles (three-electrode supercapacitors). The prepared nitrogen-doped porous carbons underwent electrochemical activation during cycling measurement, which exhibits a high energy density (27.7 Wh kg−1) and power density (7000 W kg−1) in symmetric two-electrodes supercapacitors assembled using nitrogen-doped porous carbons after 10,000 cycles.

Temperature swing adsorption for CO2 capture: Thermal design and management on adsorption bed with single-tube/three-tube internal heat exchanger

CO2 adsorption technology, especially temperature swing adsorption (TSA), is an important and effective method to reduce carbon dioxide emissions and achieve carbon neutrality. Considering the fact that adsorption bed is the most energy-intensive part in the TSA system, the thermal design and management towards internal heat exchanger (single-tube/three-tube) in adsorption bed is essential to improve energy efficiency. In this study, the self-coded TSA process including three steps (adsorption, desorption and cooling) is carried out using zeolite 13X-APG. Under the same surface area, heat transfer area, total amount of adsorbent, operation pressure and inlet flow rate, the thermal design schemes including inlet speed, porosity and adsorption/desorption temperature based on single-tube/three-tube heat exchanger in adsorption bed are discussed. The results show that the three-tube heat exchanger is superior to the single-tube heat exchanger in energy efficiency performance under the same conditions. With the increase of inlet speed and porosity, the COPCO2 (Coefficient of Performance of CO2 Capture) of the three-tube heat exchanger increased by 5.9% and 1.4%, respectively, and the specific energy consumption decreased by 8.5% and 5.4%, respectively. Decreasing of adsorption temperature, increasing of desorption temperature result in the improvement of the separation and energy-efficiency performance in adsorption bed. The findings are beneficial to optimize the geometric structure and operation strategy of the adsorption bed in TSA system.