High CO2 Capture Efficiency Research Articles

Investigation on CO2 capture performance of low-viscosity diamine non-aqueous absorbents with N-methyldiethanolamine regulation

In recent years, non-aqueous absorbents have attracted increasing attention due to their ability of significantly reducing sensible and latent heats in regeneration processes compared to conventional organic amine aqueous solution. But high viscosity of non-aqueous absorbents after CO2 absorption saturation became an obstacle to their industrial application. Here, a novel low-viscosity diamine non-aqueous absorbent for high-efficiency CO2 capture was proposed, in which N-methyldiethanolamine (MDEA) with steric hindrance effect was introduced as a regulator and dimethyl sulfoxide (DMSO) as a cosolvent. The effects of MDEA on CO2 capture performance of various non-aqueous absorbents and its regulation mechanism on CO2 absorbent viscosity were investigated systematically. Experimental results showed that when 25 wt% 2-(2-aminoethylamino)ethanol (AEEA) was screened as main CO2 absorption component, AEEA/MDEA/DMSO non-aqueous absorbent exhibited a high CO2 absorption capacity of 2.55 mol/kg and a fast CO2 absorption rate. Based on further mass fraction optimisation, it was found that the lowest viscosity of non-aqueous absorbents after CO2 absorption was 13.12 mPa s and the highest CO2 regeneration reached 93.5 % with AEEA and MDEA were 17.5 wt% and 12.5 wt%, respectively. 13C NMR tests showed that two characteristic peaks of carboxylated carbon appeared in CO2 products, which indicated that both amino groups on AEEA molecule were involved in CO2 absorption reaction. DFT calculations indicated that hydrogen bonding strength between MDEA and CO2 products was relatively lower than that of AEEA and CO2 products, which favored reducing absorbent saturation viscosity significantly. Thermodynamic analysis revealed that total regeneration energy consumption for 17.5 wt% AEEA/12.5 wt% MDEA/70 wt% DMSO non-aqueous absorbent was 1.72 GJ/t CO2, which was 53 % lower than that of MEA aqueous solution.

Pilot Testing of Calcium Looping at TRL7 with CO2 Capture Efficiencies toward 99.

Postcombustion CO2 capture by calcium looping using circulating fluidized bed technology, CFB-CaL, is evolving to tackle industrial sectors that are difficult to decarbonize. In addition to the known advantages of CFB-CaL (i.e., retrofittability and competitive energy efficiencies and cost), the fuel flexibility by using renewable biomass in the oxy-fired CFB calciner and the possibility to reach extremely high CO2 capture efficiencies in the carbonator are demonstrated in this paper. Results from the latest experimental campaigns in the TRL7 CFB-CaL pilot of the La Pereda are reported, treating over 2000 N m3/h of flue gases in the carbonator with a firing capacity of biomass pellets up to 2 MWth in the oxy-fired calciner. A new strategy to reach high CO2 capture efficiencies (above 99% in some cases) in the carbonator has been tested. This involves decoupling the carbonator in two temperature zones by cooling the solids-lean top region to below 550 °C and ensuring that a sufficient flow of active CaO reaches such a region.

An energy-efficient cyclic amine system developed for carbon capture from both flue gas and air

High energy consumption is a major barrier to the large-scale deployment of carbon capture processes from flue gases or air (direct air capture, DAC). The non-aqueous amines reported in literature possess a high energy efficiency for CO2 capture from flue gases, they struggle with gas streams containing ultra-dilute CO2, like air, due to poor absorption kinetics. This study developed novel 2-PE (2-piperidineethanol)/APZ (Aminoethylpiperazine) based CO2 absorbents to address these problems. The experiments and MD simulation results showed that the 2-PE/APZ-based absorbents possessed a superior absorption performance both in flue gas and air. Among the developed absorbents, when 2-PE/APZ mixed with DMF (Dimethylformamide), the CO2 loading reached to 1.004 mol/mole, as the theoretical maximum. In DAC tests, 87.31 % CO2 from the air was captured in 24 h experiments. The regeneration heat duty of 2-PE/APZ/DMF decreased to 1.694 KJ/g CO2, a 55.89 % reduction compared to the benchmark 30 wt% MEA. The CO2 absorption/desorption mechanism was analysed by NMR, In-situ FT-IR, and DFT calculation. It indicated that this significant improvement in CO2 absorption performance and the reduction in energy consumption are due to the synergistic effect of 2-PE and APZ. During CO2 absorption, CO2 reacts with APZ forming APZ zwitterion rapidly, then deprotonation to the 2-PE. The formation of protonated 2-PEH+ ion pairs with APZCOO- reduces hydrogen bonds and van der Waals forces among the amine-CO2 complex, facilitating easy regeneration at mild conditions while maintaining high reactivity. The combination of theoretical and experimental results indicates that 2-PE/APZ-based absorbents can serve as a promising alternative for carbon capture from flue gas to air with low energy usage.

Dual-Tuning Azole-Based Ionic Liquids for Reversible CO2 Capture from Ambient Air.

A strategy of tuning azole-based ionic liquids for reversible CO2 capture from ambient air was reported. Through tuning the basicity of anion as well as the type of cation, an ideal azole-based ionic liquid with both high CO2 capacity and excellent stability was synthesized, which exhibited a highest single-component isotherm uptake of 2.17 mmol/g at the atmospheric CO2 concentration of 0.4 mbar at 30 °C, even in the presence of water. The bound CO2 can be released by relatively mild heating of the IL-CO2 at 80 °C, which makes it promising for energy-efficient CO2 desorption and sorbent regeneration, leading to excellent reversibility. To the best of our knowledge, these azole-based ionic liquids are superior to other adsorbent materials for direct air capture due to their dual-tunable properties and high CO2 capture efficiency, offering a new prospect for efficient and reversible direct air capture technologies.

Sequestration of CO2 using emulsion phase structure

This study proposes a cost-effective method for creating an emulsion structure to capture 100 % of the CO2 released during chemical reactions. The emulsion, composed of water, kerosene, sodium lauryl sulfate (SLS), sodium hydroxide (NaOH), triethylamine (TEA), and amine-functional ion exchange resin (IER), demonstrates high CO2 capture efficiency. Results indicate that a 10 mL emulsion sample could capture 12.72 g of CO2, representing 95.4 % of the total CO2 produced during the chemical reaction between acetic acid and sodium carbonate. In contrast, an ion exchange resin granule captures only 0.01 g of CO2. Consequently, 10 mL of emulsion sample containing 60 units of IER is necessary to achieve 100 % CO2 capture.

Clathrating CO2 in a Supramolecular Granatohedron Cage with Noncovalent CO2-NH3 Interactions and High CO2 Capture Efficiency under Ambient Conditions.

Organic amine (R-NH2) reagents as dominant chemical sorbents for CO2 capture in industrial processes suffer from high energy compensation for regeneration. Herein, we, for the first time, report the finding of Co(III) coordinating with NH3 molecules regulating the interaction between NH3 and CO2 to electrostatic interactions instead of a chemical reaction and achieve CO2 capture under near-ambient conditions. NH3 coordinating with Co(III) significantly reduces its alkalinity and reactivity with CO2 owing to its lone-pair electron donation during coordination. Under a simple protocol, CO2 induces the crystallization of CO2@[Co(NH3)6][HSO4][SO4] clathrate into a hydrogen-bonded granatohedron cage from a cobaltic hexammine sulfate aqueous solution under a CO2 pressure of 56 and 142 kPa at 275 and 298 K, respectively, with a CO2 uptake weight content of 11.7%. We reveal that CO2 interacts with cobaltous hexammine via supramolecular interactions rather than chemical bonding. The clathrate spontaneously separates from the solution as single crystals and readily releases CO2 under ambient conditions in water for cyclic utilization without further treatment. In such a rapid supramolecular capture process, molecular recognition ensures exclusive CO2 selectivity, and soluble clathrate enables the spontaneous CO2 release at a low energy penalty, exhibiting excellent practical potential in carbon capture.

Porous Carbon for CO2 Capture Technology: Unveiling Fundamentals and Innovations

Porous carbon is an emerging material for the capture of CO2 from point sources of emissions due to its high structural, mechanical, and chemical stability, along with reusability advantages. Currently, research efforts are mainly focused on high- or medium-pressure adsorption, rather than low-pressure or DAC (direct air capture) conditions. Highly porous and functionalized carbon, containing heteroatoms (N, O, etc.), is synthesized using different activation synthesis routes, such as hard template, soft template, and chemical activation, to achieve high CO2 capture efficiency at various temperatures and pressure ranges. Fundamental pore formation mechanisms with different activation routes have been evaluated and explored. Higher porosity alone can be ineffective without the presence of proper saturated diffusion pathways for CO2 transfer. Therefore, it is imperative to emphasize more rational multi-hierarchical macro-/meso-/micro-/super-/ultra-pore design strategies to achieve a higher utilization efficiency of these pores. Moreover, the present research primarily focuses on powder-based hierarchical porous carbon materials, which may reduce the efficiency of the capture performance when shaping the powder into pellets or fixed-bed shapes for applications considered. Therefore, it is imperative to develop a synthesis strategy for pelletized porous carbon and to explore its mechanistic synthesis route and potential for CO2 capture.

1D-2D intercalated network CMC@g-C3N4/IL membrane with high permeability and selectivity for the CO2 capture

The structural advantages of the membrane material itself are critical to the membrane separation performance. Two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets can achieve minimal mass-transfer barrier and high gas sieving performance due to their ultra-thin thickness, inherent surface porosity and abundance of amine groups. However, the 2D g-C3N4 nanosheets are prone to stacking during the self-assembly process, which reduces the membrane permeability. Based on this line, herein, we proposed a concept of construction of 1D-2D intercalated network supported ionic liquid membrane composed by one-dimensional (1D) carboxymethylcellulose (CMC) and g-C3N4 nanosheets to overcome the low permeability of 2D graphitic carbon nitride membrane in separating CO2/N2 and CO2/CH4. The as-prepared 1D-2D intercalated network supported ionic liquid gas separation membrane exhibits superior CO2 permeance of 953.96 GPU, CO2/N2 selectivity of 55.46 in separation of CO2/N2, and CO2 permeance of 854.00 GPU, CO2/CH4 selectivity of 50.62 in separation of CO2/CH4. In addition, the resulting CMC@g-C3N4/IL membrane has excellent durability. After 120 h of testing, it still has outstanding separation performance. In short, this concept in this study provides an effective modulation of molecular sieving of g-C3N4 membrane for high-efficiency CO2 capture by combination of the advantages of the 1D (CMC) and 2D (g-C3N4) materials.

Construction of high-performance thin-film composite membrane for CO2 separation via interface engineering

High-efficiency CO2 capture has become increasingly vital for alleviating the ongoing global temperature which leads to severe impacts on virtually every aspect of human life. Thin-film composite membranes (TFCM) have attracted growing attention for conducting CO2 capture, owning to their energy-efficient and environment-friendly merits. However, the nonideal interface between the gutter layer and the separation layer hampers the fabrication of defect-free and thin separation layer, which renders low separation performance. In this work, we developed a strategy, i.e., coupling the oxygen-plasma modification with spin-coating, for engineering the interface between the gutter layer and separation layer of TFCM. Leveraging this idea, the TFC membrane, consisting polydimethylsiloxane (PDMS) served as the gutter layer and poly (ether-block-amide) (PEBA) as the thin separation layer, was manufactured by conveniently spin-coating PEBA solution on the oxygen-plasma-treated PDMS layer. The optimized PEBA-based TFCM membrane realized superior separation performance, e.g., a CO2 permeance of 2011 GPU, a CO2/N2 selectivity of 24, and 100-hour stably running, which outperformed most of the reported PEBA-based TFCM. Thus, the interface engineering strategy proposed in this study opens a new door for rational fabrication of high-performance TFCM.

Effect of alkaline nitrate addition in the CO2 chemisorption of pentalithium ferrite (Li5FeO4) at low and moderate temperatures

Li, Na and K nitrate-containing pentalithium ferrite (Li5FeO4) samples were prepared to evaluate changes of the CO2 capture process at moderate temperatures. These experiments were performed using different CO2 partial pressures and different characterization techniques, such as TG, DSC, XRD and DRIFTS. When using a CO2 saturated atmosphere, all the samples showed high CO2 capture efficiencies at lower temperatures (150–400 °C) than those observed on the pristine Li5FeO4. Specifically, lithium nitrate-containing samples presented the best CO2 capture properties. Thus, this system was further analysed through in-situ DRIFTS and DSC experiments, elucidating the Li5FeO4-CO2 reaction path. Alkali nitrate salts are melted forming eutectic phases with the carbonate produced, where the first one works as an oxygen donor/acceptor, producing reactive intermediate species improving the CO2 capture. Moreover, at the lowest temperatures, H2O presence plays an important role during the whole CO2 capture mechanism, through the lithium hydroxide formation, enabling the process of CO2 chemisorption. Finally, it was proved that Na and K nitrate-containing samples presented similar behaviours than those described for the lithium case, although CO2 capture temperature regimes were shifted depending on the alkaline nitrate.

Partial oxycombustion-calcium looping hybridisation for CO2 capture in waste-to-energy power plants

Integrating bioenergy and carbon capture and storage (BECCS) presents a great opportunity for power production with negative global CO2 emissions. This work explores a novel synergetic system that integrates membranes, partial biomass oxycombustion and the calcium looping (CaL) process. Polymeric membranes generate oxygen-enriched air (OEA) with an O2 concentration of 39%v/v, which is used for partial oxycombustion of biomass waste. The CO2-enriched flue gas evolves from the waste-to-energy plant to the CaL unit, where CO2 concentration is increased up to 90–95%v/v, ready for purification and sequestration. Compared to only oxycombustion systems, the proposed concept presents fewer technological challenges in retrofitting boilers to waste-to-energy plants. Moreover, this new approach is highly efficient as integrating membranes to produce OEA instead of cryogenic distillation systems significantly reduces energy consumption. A novel integration concept is modelled to evaluate the whole process efficiency and the effect of key parameters on the system performance, such as the temperature of the reactors, the membrane surface area, and the partial oxy-combustion degree. The results show that the so-called mOxy-CaL system has an energy consumption associated with CO2 capture below 4 MJ/kg CO2 (a 31% lower than that for a conventional CaL process), with a higher CO2 capture efficiency than oxycombustion and the CaL process separately. On the other hand, the economic analysis shows a higher CO2 capture cost for the novel configuration than for the typical CaL configuration due to the additional investment cost of the membrane system. Improvements in membrane performance by increasing its permeance and diminishing the required surface area would significantly reduce the economic cost of this novel integration. Using membranes with permeance over 400 GPU would boost the system's competitiveness.

Multi-scale design of MOF-based membrane separation for CO2/CH4 mixture via integration of molecular simulation, machine learning and process modeling and simulation

Metal-organic framework (MOF) membranes have demonstrated high efficiency for CO2 capture due to their wide range of pore sizes, high surface area, high porosity, and open metal sites. In this work, we propose a multi-scale design framework of MOF-based membrane separation for CO2/CH4 mixture via integration of molecular simulation, machine learning, and process modelling and simulation. The GCMC and MD molecular simulation is first used to evaluate adsorption isotherms, isosteric adsorption heat, self-diffusivity, activation energy, permeability, and selectivity of a MOF-based membrane (e.g., IRMOF-1) for CO2/CH4 separation at different operating conditions. It is found that the simulated isotherms at 298 K are consistent with experimental results. CO2 permeability can range from 4.090 × 104 to 3.818 × 105 barrer with variation in operating conditions. The same phenomenon is also reflected in the selectivity. We then establish prediction models of adsorption capacity and self-diffusivity using machine learning methods such as artificial neural network (ANN), which are used to calculate the permeability. The mean squared error is 0.0086, and the coefficient of determination is 0.9822. The proposed ANN models are integrated with the tanks-in-series model of a hollow fiber membrane separation process, which is simulated using the finite volume method. Three case studies illustrate the feasibility and superiority of the proposed integrated framework.

Calcium sulphoaluminate cement from solid waste with nano-TiO2 addition for high-efficiency CO2 capture

Calcium sulphoaluminate cement from solid waste (WCSA) has a relatively lower sintering temperature and low CO2 emission, meanwhile, the low cost of WCSA and the good CO2 absorption capacity make it one of the current hot topics of research. In this work, based on the optimal water-cement ratio, the effect of titanium oxide (TiO2) on the pore structure and the hydration process of WCSA were explored. The hydration process and microscopic evolution were studied by compressive strength test, carbonization test, Brunauer-Emmet-Teller measurement (BET), X-ray diffraction (XRD), the heat of hydration, thermogravimetric analysis (TG), and scanning electron microscope (SEM). The effect of nano-TiO2 on the carbon sequestration behavior of WCSA was also analyzed. The results show that WCSA with a water-cement ratio of 0.4 is the optimal carbonization substrate and nano-TiO2 will make the pore structure more uniform and dense, simultaneously increasing the adsorption pressure for the CO2. Meanwhile, the nano-TiO2 can effectively promote and regulate the crystallization, nucleation, and growth of ettringite crystals. It can be found that the WCSA containing 1% nano-TiO2 has the highest carbon capture ability among all the contents, and the ettringite crystal is concave hexahedron. The research considered that the concave surface with large specific surface energy can effectively increase the contact area between CO2 and ettringite, which greatly improved the CO2 absorption of ettringite. Overall, WCSA containing nano-TiO2 may provide some new opportunities for efficient carbon capture.

Low partial pressure CO2 capture in packed tower by EHA+Diglyme water-lean absorbent

The results of beaker experiments (Fu et al., 2021, 2022) showed that water-lean 2-ethylhexan-1-amine (EHA) + diglyme absorbent has more advantages than the commercial water-based ethanolamine (MEA) absorbent in terms of characteristics of carbon dioxide (CO2) absorption and desorption.Verifying CO2 capture characteristics in a tower facility is essential to absorbents development. In this work, a pilot packed tower was set up and the Dg16 type polypropylene step ring was taken as packing to test the capture efficiency and mass transfer performance of EHA + diglyme water-lean absorbent for low partial pressure CO2, and then the effects of gas-liquid ratio, CO2 partial pressure and packing height on the capture performance were clarified. The results showed that the absorption of CO2 by EHA + diglyme water-lean absorbent was dominated by liquid-phase mass transfer in the packed tower. Compared with aqueous 30 wt%MEA, the water-lean EHA + diglyme achieved much higher CO2 capture efficiency and overall volumetric mass transfer coefficient. This work demonstrated the transition from water-free absorption to water-lean absorption under the existence of water vapor in flue gas. It can provide basic data for the design of the CO2 capture process based on water-lean absorption in packed towers.

Anhydrous multi-hybrid absorbent with low viscosity and high regeneration efficiency for post-combustion CO2 capture

To reduce CO2 emissions, a new anhydrous multi-hybrid absorbent is developed for post-combustion CO2 capture. It was synthesized using tetraethylenepentamine-modified porous silica nanoparticles (TEPA-PSNs) as host unit and 2-[2-(dimethylamino)ethoxy]ethanol (DMEE) as solvent. The density and viscosity were higher with more TEPA-PSNs and lower temperatures. The viscosity of 50%-TEPA-PSNs/DMEE increased from 9.76 mPa s to 267.98 mPa s as TEPA-PSNs concentration rose from 5% to 20% at 27 °C. The effects of host unit concentration, amine group loading content, CO2 concentration in the gas phase, and temperature on CO2 absorption performance were investigated. The optimum absorption capacity was obtained with suitable TEPA-PSNs concentration and TEPA loading content to avoid the harmful effects of pore structure blockage and high viscosity on mass transfer. For 50%-TEPA-PSNs-10%/DMEE, higher CO2 concentration allowed better absorption capacity, which was 0.419 mmol/g at 20% CO2. The influence of increasing temperature on absorption capacity was first promoted and then inhibited, which was 0.410 mmol/g at 57 °C. Under 80 °C and N2 atmosphere regeneration conditions, the absorption capacity reached 95.0% of the initial use after five cycles. The absence of water in TEPA-PSNs/DMEE diminishes energy consumption and degradation. It is a promising CO2 capture material with low viscosity for post-combustion CO2 capture.

Controllable Construction of Amino-Functionalized Dynamic Covalent Porous Polymers for High-Efficiency CO2 Capture from Flue Gas.

The design of high-efficiency CO2 adsorbents with low cost, high capacity, and easy desorption is of high significance for reducing carbon emissions, which yet remains a great challenge. This work proposes a facile construction strategy of amino-functional dynamic covalent materials for effective CO2 capture from flue gas. Upon the dynamic imine assembly of N-site rich motif and aldehyde-based spacers, nanospheres and hollow nanotubes with spongy pores were constructed spontaneously at room temperature. A commercial amino-functional molecule tetraethylenepentamine could be facilely introduced into the dynamic covalent materials by virtue of the dynamic nature of imine assembly, thus inducing a high CO2 capacity (1.27 mmol·g−1) from simulated flue gas at 75 °C. This dynamic imine assembly strategy endowed the dynamic covalent materials with facile preparation, low cost, excellent CO2 capacity, and outstanding cyclic stability, providing a mild and controllable approach for the development of competitive CO2 adsorbents.

Regulating phase change behaviors of water-lean absorbents containing potassium prolinate and 2-butoxyethanol for CO2 capture: Effect of water content

Water-lean phase change amino acid salts (AAS) are of great interest as potential absorbents for post-combustion CO2 capture. In this work, effect of water content in the absorbent containing potassium prolinate (ProK) and 2-butoxyethanol (EGBE) on the phase behavior and capture performance was investigated to mimic water accumulation during wet flue gas treatment. Three types of phase separation behaviors were observed for the first time after CO2 absorption from the homogenous liquid, as increasing water content in the absorbent. Phase change mechanisms were proposed based on composition analysis of each phase, which can well explain the improved regeneration efficiency by desorbing CO2-rich phases for the three-phase system. Noticeably, forming liquid–liquid-solid phase change for water-lean ProK/EGBE absorbent shows a promising strategy with advantages of high energy efficiency and water balance management for CO2 capture.

Direct and continuous conversion of flue gas CO2 into green fuels using dual function materials in a circulating fluidized bed system

Carbon capture and utilization (CCU) technologies, such as CO2 methanation, generally require energy-intensive CO2 capture and separation processes prior to catalytic CO2 conversion. In contrast, integrated CO2 capture and reduction (CCR) technologies that use dual function materials (DFM) can directly convert low-concentration CO2 in flue gas or atmosphere into high-concentration CH4 or CO. In this study, we demonstrate a circulating fluidized bed (CFB) approach to enable continuous operation of CCR. In the CFB approach, the DFM (Na/Ni/Al2O3) circulates between two bubbling fluidized beds to enable steady-state cyclic operation of (1) selective capture of CO2 in flue gas/air and (2) hydrogenation of the captured CO2. We succeeded in the continuous synthesis of CH4 with high CO2 capture efficiency (>88 %) and high H2 conversion (>85 %) yielding mainly CH4 (selectivity > 99 %) as the product at high concentration (>20 % CH4) using 2 % CO2/N2 as the model flue gas.

Developing New Quinone Based Electrodes for Electrochemical Carbon Capture

The need for cost-effective carbon capture technology is rapidly increasing. To limit the global temperature increase to 1.5 degrees within the next century, the level of CO2 mitigation needs to be increased drastically [1]. Current technology, i.e., amine scrubbing, provides several challenges which limit their deployment: high regeneration energy, high operational costs and degradation at high temperatures [2]. An electrochemical approach avoids large energy losses and can selectively uptake CO2 by utilizing redox-active organic molecules. To compete with conventional chemical scrubbing, the electrochemical cell needs high power density, high CO2 uptake and long cycle stability. Redox-active molecules such as quinone-based molecules have been utilized in this area however suffer from low cycling stability due to organic molecules leaking into the electrolyte [3,4]. Quinone-polymer electrodes have shown a high efficiency for CO2 capture however are prone to quinone degradation and low active-material mass [5]. Here we present our work on a new class of quinone-based electrodes for electrochemical CO2 capture, and explore their electrochemistry in the presence and absence of CO2 and quantify their CO2 uptake capacities. This work paves the way for the design and discovery of improved electrode materials for electrochemical CO2 capture. The Intergovernmental Panel on Climate Change (2018), Global Warming of 1.5 degrees. Available at: https://www.ipcc.ch/sr15/ (Accessed: 10 December 2021)Rahimi, M., Zucchelli, F., Puccini, M. and Alan Hatton, T., 2020. Improved CO2 Capture Performance of Electrochemically Mediated Amine Regeneration Processes with Ionic Surfactant Additives. ACS Applied Energy Materials, 3(11), pp.10823-10830.Apaydin, D., Głowacki, E., Portenkirchner, E. and Sariciftci, N., 2014. Direct Electrochemical Capture and Release of Carbon Dioxide Using an Industrial Organic Pigment: Quinacridone. Angewandte Chemie International Edition, 53(26), pp.6819-6822.Ranjan, R., Olson, J., Singh, P., Lorance, E., Buttry, D. and Gould, I., 2015. Reversible Electrochemical Trapping of Carbon Dioxide Using 4,4′-Bipyridine That Does Not Require Thermal Activation. The Journal of Physical Chemistry Letters, 6(24), pp.4943-4946.Voskian, S and Hatton, T., 2019. Faradaic Electro-swing Reactive Adsorption for CO2 Capture. Energy and Environmental Science, 12(12), pp.3530-3547

Amine-incorporated adsorbents with reversible sites and high amine efficiency for CO2 capture in wet environment

CO2 adsorption in wet environments is attractive but difficult in terms of the unsatisfied adsorption capacity and low efficiency of active sites. Herein, we report the fabrication of a thermal-responsive adsorbent with reversible amine sites by copolymerizing N-acryloyl glycinamide (NAGA), N-[3-(dimethylamino)propyl]methacrylamide (DMAPM), and styrene (ST). During adsorption at 20 °C, the tertiary amines of the DMAPM units stretch out and act as the strong sites in water. The adsorption capacity can reach 98 mL g−1, corresponding to the highest amine efficiency (0.99 mol CO2 per mol amine), which is superior to most reported adsorbents. When elevating temperature for desorption, these active sites are shielded in the adsorbent particles because of the formation of intramolecular hydrogen bonds between the NAGA and DMAPM units. The exquisite utilization of thermal responsiveness endows the adsorbents with reversible amine sites and high amine efficiency, making them promising in practical CO2 capture.