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[Display omitted] • 1-dimethylamino-2-propanol/ N -(2-hydroxyethyl) ethylenediamine is biphasic solvent. • The solvent-rich phase is 66.67 % and the CO 2 loading can be up to 5.07 mol/L. • Biphasic solvents have a desorption rate 106.7% higher than conventional MEA. • The regeneration efficiency of the biphasic system as high as 71.8% in 60 min. • The regeneration heat is 54.1 % lower than conventional 5 mol/L MEA. Biphasic solvents are widely used for CO 2 capture owing to their low regeneration heats; however, they typically suffer from poor regeneration performance and excessive energy consumption. In this study, a mixture of 1-dimethylamino-2-propanol (1DMA2P) and N -(2-hydroxyethyl) ethylenediamine (AEEA) was proposed for CO 2 capture. By optimizing the 1DMA2P and AEEA concentrations, this biphasic solvent achieved superior phase separation and excellent absorption and regeneration performance. The proportion of CO 2 -rich phase was 66.67 %, with a CO 2 -rich phase loading of up to 5.07 mol/L. The desorption rate was improved by 106.7 % compared to that of conventional 5 mol/L monoethanolamine, and the regeneration efficiency up to 71.8 % in 60 min. Initially, CO 2 reacted with AEEA at a faster rate to form a carbamate product. Subsequently, 1DMA2P acted as a proton acceptor, facilitating the formation of bicarbonates and carbonates. Nuclear magnetic resonance analysis indicated that the reaction products (AEEACOO-, AEEAH+, and HCO 3 –/CO 3 2–) migrated to one phase, whereas 1DMA2P and any unreacted AEEA migrated to the other phase. Additionally, the disparity in polarity between the reactants and reaction products constituted the primary determinant for the phase transition. Notably, the regeneration heat of the 1DMA2P/AEEA biphasic solvent (1.83 GJ/t CO 2) was approximately 54.1 % lower than that of conventional 5 mol/L monoethanolamine. Owing to its superior absorption properties, excellent regeneration performance, and low regeneration heat, the 1DMA2P/AEEA biphasic solvent is a promising candidate for practical CO 2 capture systems. [ABSTRACT FROM AUTHOR]

Americans remain relatively unaware of the risks and benefits associated with carbon capture and storage (CCS) technology, including its role in combating CO2 emissions as a means to address climate change. Our goal is to determine factors that might help build awareness and knowledge of CCS so that citizens can make informed decisions about it. Specifically, we focus on perceived risks, benefits and emotions associated with CCS and intentions to seek information about it. We surveyed 970 adults from a region of Texas that has seen recent growth in the application of CCS technology. Consistent with prior research, most respondents were not aware of CCS or the risks and benefits associated with it. To explore CCS-related information -seeking intent, we sought guidance from the planned risk information -seeking model, which identifies factors that contribute to intentions to seek information about risk-related topics. The majority of the hypothesized relationships were supported, and the model accounted for 48% of the variance in intent to seek information about CCS risks and benefits. Furthermore, perceived benefits and hope played significant roles in explaining information-seeking intent. Implications for better engaging the public with the topic of CCS are discussed. [ABSTRACT FROM AUTHOR]

Phase change absorbents exhibit phase change after absorbing CO 2 and offering potential for energy savings. This review introduced applications of 3 types of phase change absorbents based on ionic liquids in CO 2 capture. [Display omitted] • Application of ionic liquids for CO 2 capture with phase change was reviewed. • Three classes of phase change CO 2 absorbents based on ionic liquids were discussed. • Various mechanisms triggering phase separation in absorbents were elaborated. • Advantages and limitations of ILs-based phase change CO 2 absorbents were provided. Research and development of novel absorbents with high efficiency and low energy consumption is the key to achieve large-scale carbon dioxide (CO 2) emissions reduction by chemical absorption method. Due to the advantages of adjustable structure, negligible vapor pressure, low specific heat capacity, and moderate reaction heat, the CO 2 capture technology based on ionic liquids (ILs) absorbents has remarkable potential for energy conservation. The applications of ILs in CO 2 capture process with phase change can further cut down the regeneration energy penalty. In this article, we reviewed the recent progress in ILs-based phase change absorbents for CO 2 capture technology, focusing on phase change behaviors, reaction and phase change mechanisms, and process flow and energy consumption analyses. Applications of ILs as solvents or absorbents in phase change absorbents were discussed including liquid–liquid biphasic absorbents, liquid–solid biphasic absorbents, and phase change ILs. We have provided challenges and outlooks on novel ILs-based phase change absorbents for CO 2 capture from laboratory research to industrial applications. [ABSTRACT FROM AUTHOR]

• An increase in the proportion "-NH-" functional groups causes lower ΔH abs. • Secondary amino functional groups appear to stimulate the growth of Δα CO2. • 2MPZR has a 10.7% lower ΔH abs than MEA. • The effective phase change solvent, 2MPRZ/TGBE/H 2 O, was proposed in this work. • The sensible heat of 2MPRZ/TGBE/H 2 O is 56 % lower than that of 5 M MEA. Energy consumption is one of the crucial factors in determining the suitability of the chemical absorbents for capturing carbon dioxide (CO 2). Polyamines have attracted increasing attention in recent years because of the existence of several amino functional groups that could effectively capture CO 2 in their molecules. In this work, the structures of seven polyamines with excellent CO 2 capture performance were investigated in relation to reaction rate and the CO 2 absorption heat. A high-precision microcalorimeter was applied to analyze the absorption heat of CO 2 directly, and a parameter defined as the CO 2 quasi-cycle capacity was employed to assess the cyclic capture capacity of CO 2 , absorption rate, and desorption rate. Experimental results revealed that for the selected polyamines, the increase in the ratio of the secondary amino functional group to the primary-one in the molecule leads to a decrease in the CO 2 absorption heat and an increase in the CO 2 cyclic capacity.The ΔH abs of the eight amines give out the order of HMDA (92.22 kJ/mol) > MAPA(90.91 kJ/mol) > AEEA (87.62 kJ/mol) > MEA (86.36 kJ/mol) > TEPA (82.95 k/mol) > AEP (82.36 kJ/mol) > 2MPRZ (77.08 kJ/mol) > PZ (74.41 kJ/mol). The CO 2 quasi-cycle capacity of 2MPZR is about twice that of the MEA. In addition, 2MPRZ was found to be an absorbent with phase change potential. The effective phase change solvent system, 2MPRZ + Triethylene glycol monobutyl ether (TGBE) + H 2 O, was developed in this work. Compared to the 5 M MEA aqueous solution, its sensible heat was reduced by 56.3 %, indicating that 2MPRZ is a promising absorbent. [ABSTRACT FROM AUTHOR]

• Three possible pathways for bicarbonate generation were investigated based on DFT. • Base-catalyzed CO 2 hydration is dominant in [N 1111 ][Gly]/EtOH aqueous system. • Water effect on phase change behavior is analyzed from hydrogen bonding view. • Water content of 5 wt% promotes products aggregation in favor of phase change. Ionic liquids-based anhydrous biphasic absorbents have the potential to lower the energy consumption for CO 2 capture. Recent experimental studies have revealed that the presence of water in [N 1111 ][Gly]/EtOH system leads to generation of a new CO 2 -product – bicarbonate and affects the phase change behavior. However, the reaction pathway for bicarbonate formation remains unclear. In this work, the reaction pathways were investigated in depth through quantum chemical calculations employing density functional theory, with reaction rate constants determined via transition state theory. Among the three possible reaction pathways, the base-catalyzed CO 2 hydration reaction prevailed, i.e. a one-step reaction involving [Gly]-, H 2 O, and CO 2. An H atom in H 2 O was transferred to [Gly]-'s amino group, forming protonated [Gly]-, and hydroxide combined with CO 2 to generate bicarbonate. Additionally, molecular dynamics simulations were conducted to understand the phase change behaviors with varying water content. When water content exceeded 5 wt%, an increased water content led to reduced hydrogen bonding among products and enhanced hydrogen bonding of products-solvent with the solvent, diminishing product self-aggregation. No phase change behavior were observed at water contents up to 80 wt%. This study could well explain the experimental phenomena of water effect on CO 2 absorption in [N 1111 ][Gly]/EtOH, providing theoretical references for application of ILs-based anhydrous biphasic absorbent. [ABSTRACT FROM AUTHOR]

• Amino acid salt was firstly introduced into EMAR process for carbon capture. • UV–Visible spectroscopy was used to analyze copper complex change during absorption. • Electrochemical behaviors and performance were discussed by comparing with MEA. • A one-step oxidation reaction was beneficial to reduce the energy consumption. • Homogeneity of electrode surface was observed in our proposed system. Electrochemically mediated amine regeneration (EMAR) for CO 2 capture is a promising substitute for traditional organic amine–based CO 2 capture by replacing the thermal process with electricity. To avoid problems such as oxidative degradation, toxicity, volatilization, and precipitation of organic amine absorbent, potassium β–alanine was suggested as an absorbent using EMAR process for the first time in this study. The CO 2 absorption performance under different copper loading and chemical reactions were studied, and cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and the Taffel extrapolation method were used to study the electrochemical characterization. Compared to the benchmark monoethanolamine (MEA) system, a smaller potential difference between oxidation and reduction peak was acquired in the potassium β–alanine system, of which the energy consumption was only 44.1% of the MEA system at the current of 100 A/m2. The cathode Faraday efficiency in the potassium β–alanine system was 101.9% higher than that in the MEA system at the current density of 25 A/m2. Furthermore, the result of scanning electron microscope of the electrode surface after desorption showed that potassium β–alanine absorbent improved the inhomogeneity of the electrode surface and was in favor of uniform current distribution. Overall, potassium β–alanine can be used as a more environmentally friendly absorbent in the EMAR system and has great potential to further reduce the actual energy consumption and improve the Faraday efficiency and cycling performance. [ABSTRACT FROM AUTHOR]

• Novel biphasic solvent based on polyamine was developed for CO 2 capture. • Microcalorimetry strategy was used to directly measure the CO 2 absorption heat. • The energy consumption of this absorbent was 32.6 % lower than that of 5 M MEA. • This biphasic solvent has superior phase-splitting behavior. • The salting-out effect was the main reason for the phase-splitting behavior. The CO 2 phase change absorbents(CPCAs) formed by introducing phase-splitting agents have attracted increasing attention because of their great energy-saving potential. However, the volatilization problem of the phase-splitting agents and the high viscosity of the solution affect the application of CPCAs. In this work, a novel CPCAs based on 2-Methylpiperazine (2MPRZ)/H 2 O was established by introducing triethylene glycol monobutyl ether (TGBE) with a high boiling point as a phase-splitting agent, and the 2MPRZ/H 2 O/TGBE system exhibited low volatility and low viscosity. The CO 2 capture performance of the novel CPCAs with different ratios was investigated in this work. The best CO 2 absorption rate was achieved by 2.5 M 2MPRZ/H 2 O/TGBE. The viscosity of this system before and after the CO 2 absorption process was merely 7.68 mPa·s and 11.64 mPa·s, respectively, and no volatilization of the phase-splitting agent was observed simultaneously. A convenient and rapid titration method was employed to determine the distribution of the 2MPRZ products in the two phases, which showed that 98 % of the 2MPRZ products were located in the CO 2 -rich phase. In addition, the CO 2 -rich phase captured 99 % of the total CO 2 , indicating that this system has superior phase-splitting behaviors. The regeneration energy consumption of this biphasic absorbent was 2.59 GJ/t CO 2 , which was 32.6 % lower than that of traditional MEA. Furthermore, the salting-out effect was proved to be the cause of the phase-splitting behavior by 13C NMR analysis. [ABSTRACT FROM AUTHOR]

• Water markedly affected phase change behaviors of anhydrous biphasic absorbents. • The presence of water was negative for CO 2 absorption but beneficial to desorption. • The main CO 2 -product was HCO 3 - in the presence of water rather than carbamate. • Effect of water on CO 2 absorption mechanism of [N 1111 ][Gly]/ethanol was clarified. The ionic liquids (ILs)-based biphasic absorbents are viewed as promising substitutes for CO 2 capture due to their remarkable CO 2 absorption performance, excellent stability and low energy requirement for regeneration. Further decreasing the regeneration heat requirement can be achieved by utilizing ILs-based anhydrous biphasic absorbents, whose solid CO 2 -rich phase contained small volume and low specific heat capacity. Given the high hygroscopicity of ILs and the water present in the flue gas, comprehending the effect of water is crucial for post-combustion carbon capture using ILs-based anhydrous biphasic absorbents. In this work, the effect of water on CO 2 absorption by an anhydrous biphasic absorbent, tetramethylammonium glycinate ([N 1111 ][Gly])/ethanol, was studied. The experimental results demonstrated that the CO 2 loading and absorption rate were decreased in the presence of water, but the CO 2 desorption efficiency was enhanced. Besides, the presence of water slightly reduced the reaction heat of CO 2 absorption by [N 1111 ][Gly]/ethanol to 69.48 kJ/mol CO 2 , which was 20% lower than that of monoethanolamine (MEA) absorbent. Furthermore, the 13C NMR results indicated that the primary CO 2 -product was bicarbonate in the presence of water rather than carbamate. There were three possible pathways for bicarbonate generation: zwitterion hydrolysis, carbamate hydrolysis, and base-catalyzed CO 2 hydration. Water and ethanol competed to react with carbamate. When a large amount of water was present (≥70 wt%), the reaction of ethanol with the carbamate hardly occurred. [ABSTRACT FROM AUTHOR]

Calcium looping process is well considered as one of the most promising technologies for trapping CO 2 from flue gas. But the drastic decay of CO 2 capture capacity and the severe attrition of the CaO-based sorbents are the two main obstacles for the calcium looping process. In order to enhance the CO 2 capture capacity and the anti-attrition property of the CaO-based sorbents, an extrusion-spherization method was proposed by biomass templating method to manufacture spherical sorbents. In addition, the effects of three components of biomass, lignin, cellulose and hemicellulose in the spherical sorbents on the cyclic CO 2 capture capacity were investigated in details. The CO 2 capture performance of the sorbents and pyrolysis of three biomass components were test by a simultaneous thermal analyzer (STA), and the attrition resistance properties of the sorbents were examined by a friability tester (FT). The microstructure of the sorbents was measured by N 2 adsorption/desorption measures, an X-ray diffraction apparatus (XRD) and a field emission scanning electron microscope apparatus (FESEM). Results showed that cellulose and hemicellulose templating processes were beneficial to the CO 2 capture performance of the sorbents, whereas lignin was detrimental. The BET surface area of the molded sorbents increased drastically when templated with cellulose or hemicellulose. The binder effect of the three components on the modeled sorbents followed the order: lignin > cellulose > hemicellulose. Extrusion-spherization process is a promising technology to manufacture spherical tough sorbents. Considering the effect of CO 2 capture capacity and the attrition resistance property, the optimal templating component of biomass is cellulose. [ABSTRACT FROM AUTHOR]

• The effect of AAEMs on char combustion characteristics in O 2 /CO 2 was studied. • Coal char combustion reaction kinetics were analyzed by different models. • The effect of O 2 content and heating rates on the K catalytic effect was studied. • The ignition and burnout of coal char were advanced by alkali metal potassium. The oxy-fuel combustion technology has attracted widespread attention because of its relatively low-cost and large-scale CO 2 capture. During the oxy-fuel combustion process, the low diffusivity of O 2 in CO 2 brings several difficulties on coal char combustion due to N 2 replacement with CO 2. Catalytic combustion by adding alkali and alkaline earth metals (AAEMs) is an effective way to improve the coal char combustion performance. In this work, the catalytic effects of AAEMs on coal char combustion characteristics under different conditions were studied. Besides, the kinetic parameters of char combustion were obtained by Kissinger-Akahira-Sunose, Starink, and Flynn-Wall-Ozawa methods. Results showed that compared with other AAEMs (Na, Ca, and Mg), K showed better catalytic effects on ignition, burnout, and comprehensive combustion characteristics of coal char. The promotion effect of K on the combustion performance was gradually saturated when addition ratios exceeded 1 wt%. At low O 2 concentrations or heating rates, K exhibited a strong catalytic effect on coal char combustion. Besides, K could accelerate the decrease in activation energy (E a) of coal char combustion as char conversion (α) increased. When α was 0.9, the reduced effect of K on the E a value was 13%. These results are expected to provide new insights into the improvement of coal char oxy-fuel combustion catalyzed by AAEMs. [ABSTRACT FROM AUTHOR]

Coal-direct chemical looping hydrogen generation (CDCLHG) is a novel process that uses coal to directly produce H 2 with inherent CO 2 capture. A key issue is to find out suitable oxygen carriers for this process. In this study, perovskite was proposed as the oxygen carrier for CDCLHG, and a series of Mn-based and Fe-based perovskite oxides were synthesized by a sol-gel method for CDCLHG reactions in a fixed-bed reactor. The results showed that BaMnO 3 was an optimal oxygen carrier for CDCLHG, which could obtain H 2 -rich gas (>85%) with a high H 2 gas production rate, about 13 times higher than that in char steam gasification. Further tests showed that the optimal reaction temperature and O/C ratio were 850 °C and 1: 0.05, respectively. XRD and XPS patterns indicated that part of the lattice oxygen in BaMnO 3 could convert to the carbonate oxygen in BaCO 3 during the fuel oxidation stage (FO stage) and obtained BaMnO 3-δ with plentiful oxygen vacancies in it. The BaMnO 3-δ could partially restore its lattice oxygen in the reduction of steam stage (RS stage) and completely recover its initial structure in the air calcining stage (AC stage). SEM images showed that the decrease of BaMnO 3 reaction performance after 9 cycles was mainly due to ash accumulation. • Perovskite is proposed as oxygen carrier for coal-direct chemical looping hydrogen generation. • BaMnO 3 showed good reactivity and stability in the CDCLHG reaction. • The reaction temperature, duration, and oxygen carrier to char ratio have great effect on CO 2 selectivity and H 2 purity. • Part of the lattice oxygen in BaMnO 3 could convert to the carbonate oxygen in BaCO 3 in FO stage. [ABSTRACT FROM AUTHOR]

• NaCl tailors the temperature sensitivity of CO 2 sorbents. • NaCl accelerates the sintering of the CaO-based sorbents. • NaCl triples the CO 2 capture capacity of the CaO-based sorbents. • Improved CO 2 diffusion leads to the higher CO 2 capture capacity of the NaCl tailored CaO. Calcium looping process is a prospective strategy to remove CO 2 from flue gas. However, the CO 2 capture capacity of the CaO-based sorbents would be spoiled severe over the repeated cycles. In this work, a kind of NaCl-modified CaO-based sorbents were prepared by a simultaneous hydration and impregnation process and explored for cyclic CO 2 capture by a simultaneous thermal analyzer. The promotion mechanism was discussed by electron microscope, X-ray diffraction, N 2 physisorption, X-ray photoelectron spectroscopy, and so on. Results showed that NaCl tailored the temperature sensitivity of CaO-based sorbents, and it was a good promoter to enhance the carbonation activity of CaO-based sorbents, especially under higher temperature modes. At higher temperatures, NaCl would cover the surface of CaO, and promote the CO 2 transportability in the modified sorbent, and then greatly improve the carbonation ability of the sorbents over the cycles. After 50 repeated cycles, the CO 2 capture capacity of "10 NaCl/CaO" still retained at 0.288 g/g and 0.237 g/g when carbonated at 650 °C and 750 °C, which were 2.05 and 2.63 times that of "CaCO 3 AR" respectively. Hence, the temperature-sensitive CaO-based sorbent promoted by NaCl shows a promising prospect for CO 2 capture from flue gas. [ABSTRACT FROM AUTHOR]