Energy Consumption For Regeneration Research Articles

Simulation and optimization for flue gas CO2 capture by energy efficient water-lean ionic liquid solvent

Ionic liquids (IL) are treated as advanced materials for energy-saving carbon dioxide (CO2) capture from flue gas but suffer from serious challenges in energy and mass management. Herein, a water-lean IL-based deep eutectic solvent with 1,8-diazabicyclo [5.4.0] undec-7-ene imidazole ([DBU] [IM]) and ethylene glycol (EG) blends was prepared with a screened proportion of IL:EG=7:3. The CO2 loading and saturated solvent viscosity were 1.89 mol/L and 95 mPa·s, respectively. The foundational properties of the IL-EG solvent were determined by experimental measurements and thermodynamic modeling. The vacuum flashing desorption technology was innovatively adopted for energy-saving solvent regeneration. Industrial-scale process simulation of multistage flashing was used to explore the energy consumption during solvent regeneration. Meanwhile, the segmented cooling paved a route for water separation from water-lean solvent. A comprehensive analysis was performed out to optimize the operating parameters for CO2 absorption and desorption. For the recommended 3-stage flashing configuration, the specific process regeneration energy consumption amounted to only 1.54 GJ/tCO2. Consequently, the total capture cost reduced to 48.1 $/tCO2, marking a decrease of 31.28 %, 16.55 % and 10.25 %, compared with MEA solvent, water-lean solvent and biphasic solvent, respectively. This work offered insights for future endeavors in the development of IL-based CO2 capture process from industrial flue gas.

Systematic experiment on adsorption, separation and regeneration of X zeolites for LNG production with different regeneration strategies: vacuum, purging, heating and hybrid combinations

This work experimentally investigated the adsorption, separation and regeneration properties of two X zeolites for natural gas deep decarbonization in liquified natural gas (LNG) production. The regeneration properties of JLOX500 and 13X were compared with relation to regeneration efficiency, energy consumption, desorption and adsorption rate of CO2, and other factors in different pathways: vacuum, purging, heating, and hybrid combinations. The results demonstrated that fresh JLOX500 with more cations and less binders had significantly greater CO2 adsorption capacities and larger separation factor (CO2/CH4) than those of fresh 13X, because of its larger micro-porosity and higher CO2 isosteric heat. Due to higher partial pressure, the adversely significant effect of CH4 competing adsorption against CO2 on adsorbent regeneration is confirmed. The flow rate increases of purge gas had no effects on regeneration efficiency for 13X when the CO2 concentration of desorbed gas reached to zero. Because of a greater cumulative pore volume, JLOX500 after sufficient regeneration has a larger CO2 adsorption capacity and a higher desorption rate of CO2 than 13X, which also makes it more efficient with regards to purge gas and energy consumption utilization. With 150 mL/min of purge gas, the energy consumptions for 13X and JLOX500 regenerated at 150 °C were 4.20 and 2.89 MJ/kg-CO2, respectively. The CH4 recovery relied on the regeneration efficiency of adsorbents, duration of adsorption, and the amount of purge gas used. Both X zeolites regenerated by purging (150 mL/min) or vacuuming at 1 kPa at 150°C could purify the feed to the CO2 content less than 50 ppm, but JLOX500 is more efficient with regards to the overall performance.

Dihydroxyl-Cooperative 1,2,4-Triazole-Based Ionic Liquid for Robust Reversible CO2 Absorption.

The development of aqueous absorbents for CO2 capture is significantly important to reduce global industrial gas emissions through high regeneration efficiency and low energy consumption. Herein, we newly designed and prepared a dihydroxylated ionic liquid (IL) bis(2-hydroxyethyl)dimethylammonium 1,2,4-triazole ([N1,1,2OH,2OH][TZ]) for highly efficient CO2 absorption through anion-cation cooperative interactions. A superior capacity of 1.33 mol of CO2 per mol of IL and excellent reversibility have been achieved by the introduction of dihydroxy sites on the ammonium-based Tz IL. 1H and 13C nuclear magnetic resonance, Fourier transform infrared, and quantum chemical calculations demonstrate bihydroxyl-cooperative absorption of CO2 via hydrogen bond interaction between the cation and anion of the IL. The theory calculation shows that IL displays a superlow reactive absorption enthalpy, favorable to the reversible CO2 absorption, which can maintain an initial absorption capacity of 98.5% with the cycle numbers of 100, implying the facile regeneration and superlow energy consumption. Thus, the functionalized ILs toward group cooperative gas absorption and excellent reversibility may open a door to designing new materials for enhancing CO2 absorption and utilization.

Molecular simulation and experimental understanding of piperazine-promoted 2-cyclopentylaminoethanol for energy-efficient carbon capture

With the serious climate change and carbon emissions issues facing the world, it is becoming increasingly important to find effective methods to reduce the post-combustion CO2 concentrations. Piperazine −enhanced aqueous amine solvents are still being developed due to the technology is more applicable to large −scale industry. However, the sustainability of the CO2 capture process is still hindered by high energy consumption and amine losses. To tackle this issue, a novel secondary amine, 2-cyclopentylaminoethanol, was synthesized from a primary amine, monoethanolamine. It has a more stable structure than monoethanolamine and was further activated by piperazine. Its effectiveness was compared with piperazine-enhanced N-methyldiethanolamine, N-methyldiethanolamine/triethylenediamine, and 2-amino-2-methyl-1-propanol. The experimental results showed that 2-cyclopentylaminoethanol/piperazine presents the fastest CO2 mass transfer rate, the largest CO2 cyclic capacity and a lower latent heat. The regeneration energy consumption of the absorbent is approximately 2.44 GJ/ton CO2, which is approximately 37.45% lower than that of 30 wt% monoethanolamine solvent. The results are in accordance with the findings of a laboratory-scale pilot plant study, which demonstrated an average reduction of 35.3% in energy consumption. Molecular simulations have revealed that 2-cyclopentylaminoethanol exhibits the lowest energy barrier for reacting with CO2, rendering it more conducive to CO2 reaction. The intermolecular interactions indicate that the hydrogen bonding in the solution after monoethanolamine reacts with CO₂ becomes more pronounced, coupled with a higher energy barrier. Consequently, a greater amount of energy is required during desorption. It can be inferred that 2-cyclopentylaminoethanol/piperazine is a promising energy-efficient and stable absorbent for post-combustion CO2 capture.

Understanding the Catalytic Effect on the CO2 Regeneration Performance of Amine Aqueous Solutions

To address the high energy consumption of the carbon capture and storage process in the shipping industry, the effects of several commonly used commercial catalysts, such as HZSM-5-25, γ-Al2O3, and SiO2, as well as a self-prepared catalyst, Zr-HZSM-5-25, on the regeneration of MEA solution and MEA + MDEA mixed solution were investigated in this paper. The results showed that Zr-HZSM-5-25 had the best catalytic effect on the regeneration process of the MEA aqueous solution, which could increase the instantaneous maximum CO2 regeneration rate of the MEA-rich solution by about 8.25% and the average regeneration rate by about 5.28%. For the MEA + MDEA mixed solution, the reaction between tertiary amine MDEA and CO2 produced a large amount of HCO3− in the reaction system, which could accelerate the release of CO2 to a large extent, which resulted in the catalytic effect of the Zr-HZSM-5-25 catalyst on the regeneration process of the mixed amine solution being significantly lower than that on the single MEA solution, with an increase of 4.91% in the instantaneous maximum regeneration rate. This instantaneous maximum regeneration rate was only increased by 4.91%. While Zr-HZSM-5-25 showed a better performance in the bench-scale test, it reduced CO2 regeneration energy consumption by 7.3%.

Synthesis of desulfurization solvent networks based on process characteristics: New insights of desulfurization units and a novel synthesis method

Synthesis of desulfurization solvent network (DSN) can reduce the solvent circulation and the energy consumption for solvent regeneration. Based on the desulfurization process characteristics, this work proposes a novel graphic to explore the operating limitations of a desulfurization unit. A feasible operating window of the desulfurization unit is presented with three boundary lines to constrain the solvent reuse. Different cases for the solvent reuse between units are analyzed in details, and two rules for rich solvent reuse are proposed and proven. A novel hierarchical method is developed for the DSN synthesis. A refinery case is investigated using the proposed method. Four DSN designs are obtained, and the fresh solvent consumption can be reduced by 13.7 %. The accuracy of the four designs is verified by rigorous simulation, showing a maximum relative error of 1.22 %. The proposed method can show clear insights in DSN synthesis and give reliable and concise designs.

Energy consumption optimization of CO2 capture and compression in natural gas combined cycle power plant through configuration modification and process integration

Currently, natural gas combined cycle (NGCC) power plants account for a quarter of global electricity power supply and lead to greenhouse gas emissions. Carbon capture and storage (CCS) is one of the most effective technologies to reduce carbon emissions in the short term. However, the monoethanolamine (MEA)-based CO2 absorption and compression process is energy-intensive, which significantly reduces the power generation efficiency of NGCC. In addition, the waste hot and cold energy from NGCC and liquefied natural gas (LNG) regasification process, which are generally wasted, can be recovered for the CCS process. Therefore, this study aims to reduce the energy consumption of the carbon capture process and recover waste LNG cold energy and hot energy in the NGCC through configuration modification and process integration. The results show that the energy consumption of CO2 regeneration in the proposed CO2 capture process configuration is reduced by 18.03 %, and the net power efficiency of the NGCC plant increases from 48.88 % to 50.10 %. Furthermore, a cascade two-stage organic Rankine cycle is integrated into the system for waste heat recovery, which can generate 5.04 MW electric power and reduce the efficiency penalty of the plant from 13.72 % to 10.29 %. By contrast, the alternative application of LNG cold energy to the CO2 compression process reduces compression power by 3.95 MW with a lower footprint and utility requirement while the efficiency penalty is decreased by 3.15 %.

Research on CO2 capture performance of DMEDA water-lean absorbents based on molecular dynamics

In recent years, a large number of studies have shown that amine based water-lean absorbents formed by amines and organic solvents exhibit high capture efficiency and low regeneration energy consumption in CO2 capture. However, there is a lack of research that combines molecular level structure with macroscopic properties. In order to optimize the performance of amine based homogeneous water-lean absorbents by utilizing the properties of organic solvents, and to explore the correlation between the macroscopic properties of the absorbents (CO2 capacity, removal efficiency, regeneration rate, regeneration efficiency, etc.) and the molecular structure of the absorbent components. We used experiments and molecular dynamics to study the linear terminal diamine DMEDA and non-proton polar solvent (DMF, DMPA, NMP, SFL, DMSO) system. It was found that the absorption and desorption performance of water-lean solvents was higher than that of aqueous solutions 30 wt% MEA and 30 wt% DMEDA, among which EFH with DMF as the solvent has better comprehensive performance. The molecular dynamics simulation was built to describe the solution structures of these absorbents. Through RDF calculations, the unique behavior of DMEDA in non-proton polar solvent was revealed on molecular level, it was found that organic solvents tend to aggregate with DMEDA molecules to form large molecular clusters, while CO2 molecules may diffuse through ordered pore structures, resulting in a significant improvement in the capture performance. And it was found that there is a quantitative relationship between the intensity of intermolecular interaction between DMEDA and CO2 and the removal efficiency change in DMEDA water-lean absorbents. A functional relationship was fitted, and a preliminary and rapid method for determining capture performance through molecular dynamics was proposed.

Performance study of activated multi-walled carbon nanotubes on catalyzing amine-based carbon capture

Organic amine solution is currently the most commonly used chemical absorbent for carbon dioxide (CO2) capture, but its drawback such as high energy consumption for regeneration of CO2 loaded solution has seriously hindered its wide application in industry. Development of catalysts could reduce the regeneration energy consumption of the process. In this study, the catalytic effects of raw multi-walled carbon nanotubes (MWCNTs) and acid-treated MWCNTs in 30 wt% monoethanolamine solution on both absorption and desorption procedures were investigated. The results showed that the addition of raw MWCNTs and acid-treated MWCNTs as catalysts both promoted the CO2 desorption rate and amount, among which the 700 ppm acid-treated MWCNTs increased the CO2 desorption amount by 48.49 %. Furthermore, both MWCNTs shortened the desorption time of CO2 as well. Stability of acid-treated MWCNTs has been examined by 20 cycles in the capture system. Characterization results indicate that the acid treatment increased the surface area of MWCNTs, and created more acid sites on their surfaces through the defected area. Both characteristics contribute to the enhanced CO2 desorption performance. Therefore, acid-treated MWCNTs can be considered as promising catalysts for promoting CO2 desorption and reducing energy consumption for CO2 capture.

A Novel Phase Change Absorbent for CO2 Capture with Low Viscosity and Effective Absorption–Desorption Properties

Excessive carbon dioxide (CO2) emissions can lead to environmental problems, and the use of phase change absorbents for CO2 capture has received much attention due to their excellent absorption and desorption properties. Herein, a novel liquid–liquid phase change absorbent consisting of N‐aminoethylpiperazine (AEP), diethylene glycol dimethyl ether (DEGDME), and H2O is utilized. Under the optimal absorption conditions, the absorption capacity is 1.23 mol CO2·mol−1 amine. The rich‐phase viscosity of the AEP/DEGDME/H2O solution is only 6.2 mPa s−1, and the rich phase‐to‐volume ratio is 52.7%, which is suitable for industrial applications. After five cycles of absorption–desorption experiments, the cyclic capacity reaches 0.62 mol CO2·mol−1 amine. However, it should be noted that this leads to an increase in the viscosity of the solution with time. The 13C Nuclear Magnetic Resonance characterization is used to analyze the material distribution and phase separation mechanism, and it is found that during the absorption process, the carbamate and carbonate products generated by the reaction of the amino group in the AEP with CO2 are mainly located in the rich phase, while the DEGDME and H2O mainly remain in the lean phase. In the desorption process, most of the absorbed products are decomposed, and the regeneration efficiency is 66.8%. Through the regeneration energy consumption experiment, when the regeneration efficiency is 56%–67%, the total regeneration energy consumption is 2.71–2.89 GJ t−1 CO2, which is 0.91–1.09 GJ t−1 CO2 lower than that of the regeneration efficiency of 30 wt% MEA solution at 63%, which indicates that this absorbent has certain energy‐saving advantages.

Efficient CO2 capture by non-aqueous imide/ethylene glycol solvent

Man-made CO2 emissions give rise to an important influence on climate and human survival, which has attracted widespread attention. Traditional absorbents such as aqueous amines used for CO2 capture often suffer from high regeneration energy and corrosiveness. In this regard, non-aqueous amine solutions have high energy-saving potential because organics have lower vaporization enthalpy and heat capacity than water. Herein, we explored the potential absorbent composed of ethylene glycol and imide-based bases to capture CO2. The CO2 uptake in imide-based ethylene glycol absorbent was studied, experimental results showed that succinimide/glycol-20 wt% have the highest CO2 solubility, and still maintains a high absorption capacity after 8 regeneration cycles. And the absorption mechanism has been confirmed the possible intermolecular hydrogen bonding and van der Waals forces between carbon dioxide and succinimide molecules through molecular simulation. The regeneration energy consumption is only 2.243 GJ/t CO2 through process simulation calculation, which is lower than the conventional absorbent, further indicating that the fabricated absorbent have exhibits the large potential to absorb CO2 from flue gas.

Revealing the potential of cyclic amine morpholine (MOR) for CO2 capture through a comprehensive evaluation framework and rapid screening experiments

The present study comprehensively evaluates the CO2 capture performance of morpholine (MOR) at concentrations of 2 M, 5 M, and 7 M, comparing its effectiveness against conventional amines, monoethanolamine (MEA) and 2-(methylamino)ethanol (MAE). The assessment criteria include CO2 absorption rate, desorption rate, cyclic capacity, regeneration energy consumption, and relative economic cost. Utilizing 13C Nuclear Magnetic Resonance (NMR) technology, we analyzed the variations in ion concentration of the amine solvents under different CO2 loadings to reveal the reaction mechanisms of MOR with CO2. Our results demonstrate that MOR outperforms MEA and MAE in CO2 capture performance, particularly excelling in desorption efficiency. At a concentration of 7 M, MOR exhibited a 357.86% increase in average desorption rate and a 46% larger cyclic capacity compared to MEA. Additionally, MOR showed a 33.33% reduction in regeneration energy consumption and a 7.89% decrease in relative economic cost. The comprehensive evaluation method developed in this study indicates that MOR, with its high thermal stability and low corrosivity, maintains excellent CO2 capture performance at high amine concentrations, suggesting it as a promising absorbent for industrial applications. The findings contribute to the optimization of amine-based CO2 capture technologies and provide a robust framework for the selection and assessment of amine solvents, paving the way for more sustainable and cost-effective carbon capture solutions.

Novel tri-solvent amines absorption for flue gas CO2 capture: Efficient absorption and regeneration with low energy consumption

Blended amine scrubbing is considered as a promising alternative to the monoamine scrubbing process due to the potential for enhanced CO2 capture efficiency and reduced energy consumption. However, striking a balance between absorption rate and regeneration energy consumption in blended amine systems by establishing suitable interactions between activated amines and proton-acceptor amines remains a significant challenge. In this study, a novel blended amine system, involving tertiary amine diethanolamine (DEEA) as the main agent and several monoamines as promoters, was first proposed to achieve highly effective CO2 capture. The designed tri-solvent amine system of DEEA combined with piperazine (PZ) and 4-amino-1-methylpiperidine (PD) (denoted as DEEA + PZ + PD) exhibited exceptional CO2 loading (0.988 mol CO2/mol amine), superior cyclic capacity (0.788 mol CO2/mol amine), and reduced regeneration heat duty (2.14 GJ/t), surpassing monoethanolamine (MEA) by 79.6 %, 277 %, and decreasing by 43.7 %, respectively. Furthermore, the performance improvement mechanism of DEEA + PZ + PD was systematically elucidated, showcasing the swift CO2 absorption facilitated by PD or PZ in the initial reaction phase, and the subsequent formation of bicarbonate from PDCOO− and DEEA in the later stage, enhancing CO2 absorption capacity. The predominant reaction products, bicarbonate and unstable carbamate (PZ(COO−)2, PDCOO−), contribute to the high regeneration efficiency and minimal energy consumption during regeneration for DEEA + PZ + PD. Consequently, this facilely prepared tri-solvent amine system, characterized by high capture efficiency and low energy consumption, holds promise for achieving carbon–neutral operations in coal-fired power plants.

High-coercivity nanocrystalline Nd-Fe-B powder regenerated from sludge via in-situ mechanochemical approach

The regeneration of Nd-Fe-B sludge is of great practical significance for achieving the sustainable development and recycling of rare earth elements. In this study, the in-situ regeneration of sludge was realized at a lower temperature of 850 °C via the mechanochemical approach based on ball-milling and Ca-reduction diffusion. Single-phase nanocrystalline magnetic powders with high coercivity were prepared by regulating the experimental parameters and rare earth elements. The grain size of Nd-Fe-B powder obtained by 5 wt% TbHx addition was 68.1 nm, with a high coercivity of 18.38 kOe. After purification and dehydrogenation, the coercivity was 6.68 kOe, and the coercivity mechanism was controlled by reverse magnetic domain nucleation. The low temperature in this study significantly reduced the energy consumption for the calcium reduction regeneration of sludge. It facilitated the preparation of nanocrystalline Nd-Fe-B powders with high coercivity, offering a new idea for recycling Nd-Fe-B sludge.

Adjusting the phase transition time node of a solid–liquid biphasic solvent based on 2-amino-2-methyl-1-propanol for efficient CO2 capture: Insight into the regulatory effect of aminoethylethanolamine

Solid-liquid biphasic solvents (SLBSs) hold promise as energy-efficient candidates for CO2 capture. Nevertheless, the premature phase transition of current SLBSs leads to inopportune solid precipitation, posing operational challenges for the CO2 capture system. This study proposed a promising strategy that using aminoethylethanolamine (AEEA) as a regulator to fine-tune the phase transition time node of the 2-amino-2-methyl-1-propanol (AMP)/N-methylpyrrolidone (NMP) SLBS, enabling the phase transition to occur precisely as desired. Experimental results showed that the AEEA/AMP/NMP (A/A/N) SLBS exhibited tunable phase transition time nodes, modulated by the concentration of AEEA. Specifically, with the addition of 0.2 mol·L−1 AEEA, the CO2 loading associated with the phase transition increased significantly, from 0.19 to 0.54 mol·mol−1, approaching the saturation loading of 0.57 mol·mol−1. The delayed phase transition would facilitate the CO2 absorption operation. The regulatory mechanism of AEEA on the phase transition were thoroughly studied via 13C NMR and quantum calculations. AMP reacted with CO2 to produce AMPCOO− and AMPH+, which had a significantly stronger affinity for each other than for the solvent NMP, mediated by strong hydrogen bond interactions. Consequently, the continuous and fast aggregation of AMPCOO− and AMPH+ caused their swift precipitation from NMP. With the introduction of AEEA, the derived product AEEAH+(S)COO–(P) acted as a bridge-builder, connecting AMPCOO− or AMPH+ and NMP via hydrogen bonds, increasing the solubility of the AMP-derived products in NMP, thus effectively delaying the phase transition. Thermodynamic analysis revealed that the A/A/N SLBS exhibited a total regeneration energy consumption of 1.94 GJ·ton−1 CO2, representing a significant reduction of 48.9 % compared to that of 30 wt% MEA. This study provided a novel idea for designing SLBSs with controllable phase transition behavior, and offered a promising A/A/N SLBS for energy-efficient CO2 capture.

Reduce energy consumption for organic amine regeneration by MnOOH/HZSM-5 catalysts

Catalytic regeneration has become one of the most promising technologies to solve the high energy consumption problem of CO2 capture in organic amine solutions. As the most mainstream type of catalyst, the instability of acidic catalysts in alkaline solutions attracts increasing attention from researchers. Herein, we proposed a composite catalyst of MnOOH loaded HZSM-5 to weaken the adsorption of alkaline substances and improve the catalytic stability of the catalytic material. The optimized catalytic effect is obtained when the mass ratio of MnOOH is 20% The CO2 desorption efficiency is increased by 68.2%, and the energy consumption is reduced by 31.8% when the dosage of the catalyst is only dosage of 0.2 wt% amine solution. Through materials characterization and DFT calculations, it was found that the surface O and hydroxyl groups on MnOOH are the key factors for proton cycling, and HZSM-5 has an important impact on improving proton transfer rate. This work provides a valuable approach to solving the stability problem of acidic catalysts.

Synergy between electron donor and steric hindrance in Alkylated-Piperazine absorbents for efficient CO2 capture

Piperazine (PZ) and its derivatives are currently regarded as novel amine absorbents for efficient CO2 capture. However, the in-depth investigation of CO2 capture and understanding of the structure–activity relationship in PZ-based absorbents are still lacking. In this study, we conducted a systematic investigation of CO2 capture within the alkylated PZ-based absorbents. The results demonstrated that the increased alkylation degree can promote CO2 absorption by enhancing the electron donor effect of the secondary amine group in PZ. In addition, the incorporated alkyl group in PZ-based absorbent improves the CO2 desorption process by enhancing the steric hindrance effect. Particularly, the synergy between electron donor and steric hindrance effects in isopropyl alkylated-PZ (IPPZ) enables it to present enhanced cyclic capacity and remarkably low regeneration energy consumption (2.36 GJ·t−1 CO2) for CO2 capture. The present study makes a valuable contribution towards the future design and development of highly efficient absorbents for CO2 capture.

MODELING AND SIMULATION OF POST-COMBUSTION CO 2 CAPTURE PROCESS FOR 6.4 MWE BAGASSE FUELED POWER PLANT

The emission of carbon dioxide, a greenhouse gas, contributes to the phenomenon of climate change; the largest source of carbon dioxide emissions are fossil fuel power plants. Post-combustion carbon capture (PCC) technology, which is based on solvents, is currently the most advanced technology for reducing carbon dioxide emissions from power plants. The Post-combustion Process, which uses conventional solvents, has a number of disadvantages, including high energy consumption for regeneration, solvent losses, corrosion of equipment, thermal instability, and environmental impact. Ionic liquids (ILs) and IL-based solvents have produced a novel method of CO 2 capture that is highly efficient, economical, and environmentally friendly. A rate-based steady-state model of the PCC process using the ionic liquid 1-hexyl-3-methylimidazolium glycine ([Hmim] [Gly]) was investigated using Aspen Plus ®. In Aspen Plus ® Electrolyte NRTL method and RK equation of state are used to compute liquid and vapor properties. From the process analysis carried out, it was found that the height and diameter of the absorber packing, the liquid-to-gas ratio and the solvent and flue gas temperatures have a positive effect on the CO 2 capture efficiency. The result showed a maximum CO 2 capture efficiency of 92% at a packed height of 12m and diameter of 0.9m. The best capture efficiency of 98.82% was achieved at an L/G ratio of 4.0.the process simulation study examined five key parameters for ([Hmim] [Gly]) solvent which may reduce the energy and cost required for CO 2 capture. The results show that aqueous ([Hmim] [Gly]) is a promising absorbent for CO 2 capture. Offering a pathway towards more sustainable and efficient carbon capture technologies. This study contributes to the advancement of carbon capture technologies and underscores their significance in mitigating climate change impacts.

Performance study on an energy-efficient TSA air-purification process utilizing compression heat regeneration

A novel compression heat regeneration TSA process is disclosed in this paper, which aims to reduce the regeneration energy consumption of the raw air purifier in the air separation process. Since air separation is an energy-intensive process accounting for a significant proportion (about 5 %) of China's total electricity consumption, this new process holds great significance in energy conservation. Distinguishing from traditional processes, the new one integrates components such as a compressor, a regenerator, and an expander to meet the regeneration heat requirements of the purifier with minimal electrical energy consumption. It also recovers the waste heat from the tail gas to enhance the expander’s power generation, thereby realizing efficient and comprehensive energy utilization. Mathematical models have been established for components such as the adsorber, compressor, and expander, and simulations have been conducted based on actual data from an industrial-grade purifier. Consequently, historical parameter curves and bed profiles at the inlet and outlet of the adsorber have been obtained, providing insights into the purification performance and regeneration effectiveness of the new process. Furthermore, the inlet and outlet parameters, as well as the power consumption of the compressor and expander, have been determined. The temperature bed profiles and temperature history curves at the inlet and outlet of the regenerator have also been obtained. Subsequently, a comparison has been made between the new and traditional processes regarding energy consumption, and an economic assessment of the new process has been conducted based on its energy-saving potential. The following conclusions have been drawn through comparative analysis: (1) Compared to the traditional process, the new process can save approximately 51.6 % of electrical energy; (2) The payback period for retrofitting the traditional process to the new one is approximately 1.93 years.

Experimental and theoretical investigation of an ionic liquid-based biphasic solvent for post-combustion CO2 Capture: Breaking through the “Trade-off” effect of viscosity and loading

To break through the “trade-off” effect of biphasic solvents between rich-phase viscosity and CO2 loading, we synthesized a novel ionic liquid (diethylenetriamine-3-hydroxypyridine, [DETA][3HPyr]) with multiple active sites and combined it with the organic solvent diethylene glycol monobutyl ether (DGME) and water to prepare a biphasic solvent for CO2 absorption, the best absorption condition was optimized. The results demonstrated that after absorption, the solvent transformed from homogeneous to biphasic with highly self-concentrated absorption products in the rich phase. The volume of the rich phase accounted for only 36.3 % of the total solvent, while its viscosity decreased significantly to 28.1 mPa·s, with a high blend absorption capacity of 2.67 mol·kg−1. The species of absorption product and absorption mechanism was investigated using 13C NMR. The stable presence of carbamic acid in the system was confirmed, contributing to enhanced absorption capacity. Density functional theory calculations revealed that DGME stabilized carbamic acid through intermolecular hydrogen bonding interactions, and highly polar ions generated during absorption and uneven charge distribution between ions dominated the phase-change process and increased the water content in the rich phase. Thermodynamic energy barrier calculation showed that the solvent effect of DGME reduced the Gibbs free energy barriers of proton transfer and facilitated reaction progress. 3IL4D3H exhibited excellent cyclic performance with low regeneration energy consumption at 1.77 GJ·t−1. This is the first work to revealing the intrinsic dynamics of carbamic acid formation, and provides a new perspective for the phase-change mechanism of ionic liquid-based biphasic solvent.