The AEROPILs Generation: Novel Poly(Ionic Liquid)-Based Aerogels for CO2 Capture

CO₂ levels in the atmosphere are increasing exponentially. The current climate change effects motivate an urgent need for new and sustainable materials to capture CO₂. Porous materials are particularly interesting for processes that take place near atmospheric pressure. However, materials design should not only consider the morphology, but also the chemical identity of the CO₂ sorbent to enhance the affinity towards CO₂. Poly(ionic liquid)s (PILs) can enhance CO₂ sorption capacity, but tailoring the porosity is still a challenge. Aerogel’s properties grant production strategies that ensure a porosity control. In this work, we joined both worlds, PILs and aerogels, to produce a sustainable CO₂ sorbent. PIL-chitosan aerogels (AEROPILs) in the form of beads were successfully obtained with high porosity (94.6–97.0%) and surface areas (270–744 m²/g). AEROPILs were applied for the first time as CO₂ sorbents. The combination of PILs with chitosan aerogels generally increased the CO₂ sorption capability of these materials, being the maximum CO₂ capture capacity obtained (0.70 mmol g⁻¹, at 25 °C and 1 bar) for the CHT:P[DADMA]Cl_30% AEROPIL.     

CO2 Absorption Mechanism by the Deep Eutectic Solvents Formed by Monoethanolamine-Based Protic Ionic Liquid and Ethylene Glycol

Deep eutectic solvents (DESs) have been widely used to capture CO₂ in recent years. Understanding CO₂ mechanisms by DESs is crucial to the design of efficient DESs for carbon capture. In this work, we studied the CO₂ absorption mechanism by DESs based on ethylene glycol (EG) and protic ionic liquid ([MEAH][Im]), formed by monoethanolamine (MEA) with imidazole (Im). The interactions between CO₂ and DESs [MEAH][Im]-EG (1:3) are investigated thoroughly by applying ¹H and ¹³ C nuclear magnetic resonance (NMR), 2-D NMR, and Fourier-transform infrared (FTIR) techniques. Surprisingly, the results indicate that CO₂ not only binds to the amine group of MEA but also reacts with the deprotonated EG, yielding carbamate and carbonate species, respectively. The reaction mechanism between CO₂ and DESs is proposed, which includes two pathways. One pathway is the deprotonation of the [MEAH]⁺ cation by the [Im]⁻ anion, resulting in the formation of neutral molecule MEA, which then reacts with CO₂ to form a carbamate species. In the other pathway, EG is deprotonated by the [Im]⁻, and then the deprotonated EG, HO-CH₂-CH₂-O⁻, binds with CO₂ to form a carbonate species. The absorption mechanism found by this work is different from those of other DESs formed by protic ionic liquids and EG, and we believe the new insights into the interactions between CO₂ and DESs will be beneficial to the design and applications of DESs for carbon capture in the future.     

Modeling of CO2 Solubility in Selected Imidazolium-Based Ionic Liquids

This study explores the use of COSMO-RS model and Peng-Robinson (PR) equation of state (EoS) to predict the solubility of carbon dioxide (CO₂) in specific ionic liquids (ILs). COSMO-RS was employed to estimate of CO₂ solubility at atmospheric pressure in eight imidazolium-based ILs resulting from the combination of ethyl, butyl, hexyl, and octyl-imidazolium cations with two anions: bis(trifluoromethylsulfonyl)imide ([Tf₂N]) and Trifluoromethanesulfonate ([TFO]). The results indicated relatively acceptable qualitative consistency between the experimental and predicted values. The PR EoS was employed at high pressure by tuning the interaction parameters to fit the experimental data reported in the literature. The model demonstrated excellent accuracy in predicting the solubility of CO₂ at pressure values less than the critical pressure of CO₂; however, at higher pressures, the calculated solubility diverged from the experimental values. Furthermore, the type of anion and cation used in the IL affected the performance of the PR EoS.     

Study on the influence of SDS and THF on hydrate-based gas separation performance

Hydrate additives can be used to mitigate hydrate formation conditions, promote hydrate growth rate and improve separation efficiency. CO₂ + N₂ and CO₂ + CH₄ systems with presence of sodium dodecyl sulfate (SDS) or tetrahydrofuran (THF) are studied to analyze the effect of hydrate additives on gas separation performance. The experiment results show that CO₂ can be selectively enriched in the hydrate phase. SDS can speed up the hydrate growth rate by facilitating gas molecules solubilization. When SDS concentration increases, split and loss fraction increase initially and then decrease slightly, resulting in a decreased separation factor. The optimum concentration of SDS exists at the range of 100–300 ppm. As THF can be easily encaged in hydrate cavities, hydrate formation condition can be mitigated greatly with its existence. Additionally, THF can also strengthen hydrate formation. The THF effect on separation performance is related to feed gas components. CO₂ occupies the small cavities of type II hydrate prior to N₂. But the competitiveness of CO₂ and CH₄ to occupy cavities are quite fair. The variations of split fraction, loss fraction and separation factor depend on the concentration of THF added. The work in this paper has a positive role in flue gas CO₂ capture and natural gas de-acidification.     

Effects of potassium on the chemisorption of CO2 and CO on the Mo2C/Mo(100) surface

The interaction of CO₂ with K-promoted Mo₂C/Mo(100) has been studied with high-resolution electron energy loss spectroscopy, work function measurements and temperature-programmed desorption. Pre-adsorbed potassium dramatically affects the adsorption behavior of CO₂ on the Mo₂C/Mo(100) surface. It increases the rate of adsorption, the binding energy of CO₂ and it induces the dissociation of CO₂ through the formation of negatively charged CO₂. Potassium adatoms also promote the dissociation of adsorbed CO over Mo₂C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Complexes in the Photocatalytic Reaction of CO(2) and H(2)O: Theoretical Studies

Complexes (H(2)O/CO(2), e-(H(2)O/CO(2)) and h(+)-(H(2)O/CO(2))) in the reaction system of CO(2) photoreduction with H(2)O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H(2)O/CO(2) captured photo-induced electron and hole produced e-(H(2)O/CO(2)) and h(+)-(H(2)O/CO(2)), respectively. The results revealed that CO(2) and H(2)O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO(2) and H(2)O, which might be attributed to the synergistic effect and which could not be captured experimentally.     

接枝型聚离子液体聚砜膜制备及CO2分离性能 （着急）

聚离子液体是一种具有较高CO2选择性的新型膜材料,然而,由于可聚合离子液体的种类少、价格昂贵,难以实现工业应用。对此,本文提出以商业化芳族聚合物聚砜（PSf）为基础材料,通过简单可控的氯甲基化和咪唑鎓化反应,制备接枝型聚离子液体—咪唑鎓化聚砜（PSf-g-[MIm][Cl]）膜。研究了咪唑鎓化程度、操作温度、操作压力对膜性能的影响,结果表明该膜材料具有较好的压力稳定性,并且咪唑鎓（MIm）基团含量会极大的影响其性能,随着咪唑鎓化程度的增加,膜内MIm基团逐渐形成连续的传递通道,CO2渗透系数和选择性显著提高。本文制备的聚离子液体,咪唑鎓化程度最高达172%,具有良好的成膜性,在25 ℃、0.4 MPa以及增湿条件下进行测试,CO2渗透系数达到66.4 barrer,CO2/N2选择性为118.4。     

SO2 Absorption/Desorption Characteristics of Two Novel Phosphate Ionic Liquids

Two kinds of phosphate ionic liquids were synthesized and their SO₂ absorption performance was investigated. It was found that both ionic liquids could readily absorb SO₂, and the absorption capacity could reach 2.8 and 2.7 mol SO₂ per mole ILs, respectively, at ambient temperature and under normal pressure. Moreover, the cycle of SO₂ absorption and desorption from ionic liquids was repeated for four times and no change in the absorption capacity was observed. FT-IR spectrum and ¹H NMR were used to characterize the microstructure of SO₂-absorbed ILs and ILs, analysis showed that both ionic liquids absorbed SO₂ purely by physical absorption. Comparing with the previous reported ionic liquids such as [Bmim][PF6] and [Emim][BF4], the synthesized ionic liquids showed higher absorption capacity, due to the anion based phosphate (O?P?O) with the free electrons on the oxygen interacting with the Lewis acidic sulfur of SO₂, and then showing a great affinity for SO₂.     

Optimization of a High Pressure CO2 Antisolvent Process for the Recycling of Polystyrene Wastes

The recycling of polystyrene wastes by precipitation from limonene solutions using CO₂ as antisolvent is an alternative and original environmentally friendly route to recover high quality wastes. The most suitable working conditions to conduct the process are selected based on the accurate knowledge of the phase equilibrium for the ternary mixture. To maximize the recycling of polymeric wastes while the consumption of CO₂ and limonene is minimized, high values of pressure (≥100 bar), low values of temperature (≤30°C) and moderated concentrations of polymer (≤0.4 g PS/ml limonene) are required.     

Ionogels Based on Poly(methyl methacrylate) and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties

Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs.     

Intelligent Prediction of CO2 Capture in Propyl Amine Methyl Imidazole Alanine Ionic Liquid: An Artificial Neural Network Model

The objective of this paper is to create a new artificial neural network (ANN) model to predict solubility of CO₂ in a new structure of task specific ionic liquids called propyl amine methyl imidazole alanine [pamim][Ala]. Equilibrium data of CO₂ solubility were measured at the temperatures of 25, 40, and 60°C and the pressures up to 50 bar. For the purpose of performance comparison, the two most common types of ANNs, multilayer perceptron (MLP) network and radial basis function (RBF) network were used. Water content, ionic liquid content, temperature, and pressure set as input variables to ANN, while CO₂ capture rate assigned as output. Based upon optimization process, MLP neural network with 14 neurons in the hidden layer, log-sigmoid transfer function in the hidden layer and linear transfer function in the output layer, exhibited much better performance in prediction task than RBF neural network with the same neuron numbers in the hidden layer. Results obtained demonstrated that there is a very little difference between the estimated results of ANN approach and experimental data of CO₂ capture rate for the training, validation, and test data sets. Furthermore, Henry’s law constants were obtained by fitting the equilibrium data.     

Pathways for CO2 Formation and Conversion During Fischer–Tropsch Synthesis on Iron-Based Catalysts

CO₂ reaction and formation pathways during Fischer–Tropsch synthesis (FTS) on a co-precipitated Fe–Zn catalyst promoted with Cu and K were studied using a kinetic analysis of reversible reactions and with the addition of ¹³C-labeled and unlabeled CO₂ to synthesis gas. Primary pathways for the removal of adsorbed oxygen formed in CO dissociation steps include reactions with adsorbed hydrogen to form H₂O and with adsorbed CO to form CO₂. The H₂O selectivity for these pathways is much higher than that predicted from WGS reaction equilibrium; therefore readsorption of H₂O followed by its subsequent reaction with CO-derived intermediates leads to the net formation of CO₂ with increasing reactor residence time. The forward rate of CO₂ formation increases with increasing residence time as H₂O concentration increases, but the net CO₂ formation rate decreases because of the gradual approach to WGS reaction equilibrium. CO₂ addition to synthesis gas does not influence CO₂ forward rates, but increases the rate of their reverse steps in the manner predicted by kinetic analyses of reversible reactions using non-equilibrium thermodynamic treatments. Thus the addition of CO₂ could lead to the minimization of CO₂ formation during FTS and to the preferential removal of oxygen as H₂O. This, in turn, leads to lower average H_2/CO ratios throughout the catalyst bed and to higher olefin content and C₅₊ selectivity among reaction products. The addition of ¹³CO₂ to H₂/¹²CO reactants did not lead to significant isotopic enrichment in hydrocarbon products, indicating that CO₂ is much less reactive than CO in chain initiation and growth. We find no evidence of competitive reactions of CO₂ to form hydrocarbons during reactions of H₂/CO/CO₂ mixtures, except via gas phase and adsorbed CO intermediates, which become kinetically indistinguishable from CO₂ as the chemical interconversion of CO and CO₂ becomes rapid at WGS reaction equilibrium.     

HREELS study of photo-induced formation of CO2 anion radical on Rh(111) surface

High-resolution electron loss spectroscopy revealed, probably for the first time, that the illumination of adsorbed CO₂ on K-promoted Rh(111) induces or enhances formation of the CO₂ radical.This laboratory is a part of the Center for Catalysis, Surface and Material Science at the University of Szeged.     

Effect of CO(2) Enrichment on Synthesis of Some Primary and Secondary Metabolites in Ginger (Zingiber officinale Roscoe)

The effect of two different CO(2) concentrations (400 and 800 μmol mol(-1)) on the photosynthesis rate, primary and secondary metabolite syntheses and the antioxidant activities of the leaves, stems and rhizomes of two Zingiber officinale varieties (Halia Bentong and Halia Bara) were assessed in an effort to compare and validate the medicinal potential of the subterranean part of the young ginger. High photosynthesis rate (10.05 μmol CO(2) m(-2)s(-1) in Halia Bara) and plant biomass (83.4 g in Halia Bentong) were observed at 800 μmol mol(-1) CO(2). Stomatal conductance decreased and water use efficiency increased with elevated CO(2) concentration. Total flavonoids (TF), total phenolics (TP), total soluble carbohydrates (TSC), starch and plant biomass increased significantly (P ≤ 0.05) in all parts of the ginger varieties under elevated CO(2) (800 μmol mol(-1)). The order of the TF and TP increment in the parts of the plant was rhizomes > stems > leaves. More specifically, Halia Bara had a greater increase of TF (2.05 mg/g dry weight) and TP (14.31 mg/g dry weight) compared to Halia Bentong (TF: 1.42 mg/g dry weight; TP: 9.11 mg/g dry weight) in average over the whole plant. Furthermore, plants with the highest rate of photosynthesis had the highest TSC and phenolics content. Significant differences between treatments and species were observed for TF and TP production. Correlation coefficient showed that TSC and TP content are positively correlated in both varieties. The antioxidant activity, as determined by the ferric reducing/antioxidant potential (FRAP) activity, increased in young ginger grown under elevated CO(2). The FRAP values for the leaves, rhizomes and stems extracts of both varieties grown under two different CO(2) concentrations (400 and 800 μmol mol(-1)) were significantly lower than those of vitamin C (3107.28 μmol Fe (II)/g) and α-tocopherol (953 μmol Fe (II)/g), but higher than that of BHT (74.31 μmol Fe (II)/g). These results indicate that the plant biomass, primary and secondary metabolite synthesis, and following that, antioxidant activities of Malaysian young ginger varieties can be enhanced through controlled environment (CE) and CO(2) enrichment.     

Low Temperature Liquid State Synthesis of Lithium Zirconate and its Characteristics as a CO2 Sorbent

Abstract

In this study, a new preparation method providing greatly improved CO₂ sorption is introduced. Li₂ZrO₃ sorbent was prepared by low temperature co‐precipitation and compared in CO₂ sorption performance with a sorbent prepared by the conventional high temperature solid‐state reaction method. The two sorbents were characterized using scanning electron microscopy, X‐ray diffraction and thermo‐gravimetric analysis. The Li₂ZrO₃ powder prepared by the relatively simple co‐precipitation method showed significantly better performance than the one prepared by solid‐state reaction with respect to both kinetics and CO₂ sorption capacity. Extensive study of the powder prepared by co‐precipitation has been performed at various conditions.     

Experimental study on CO2 hydrate formation in the presence of TiO2, SiO2, MWNTs nanoparticles

ABSTRACT

A series of experiments on CO₂ hydrate formation were carried out in the presence of titanium dioxide (TiO₂), silicon dioxide (SiO₂), multi-walled carbon nanotubes (MWNTs) nanoparticles. The effects of these nanoparticles on induction time, final gas consumption, and gas storage capacity have been investigated at the temperature of 274.15 K and the initial pressure of 5.0 MPa.g. The induction time of CO₂ hydrate formation was remarkably shortened to 12.5 min in the presence of 0.005 wt% MWNTs nanoparticles. The high thermal conductivity and heat capacity of MWNTs nanoparticles presented better heat transfer, and large surface area provided more suitable sites for heterogeneous nucleation of CO₂ hydrate.     

Study on the Reactivity of Aldehydes in Electrolyzed Ionic Liquids: Benzoin Condensation – Volatile Organic Compounds (VOCs) vs. Room Temperature Ionic Liquids (RTILs)

The benzoin condensation of aromatic and heteroaromatic aldehydes, catalyzed by electrochemically generated N‐heterocyclic carbenes, has been set up in the absence of organic solvents and bases. α‐Hydroxy ketones have been isolated in good to elevated yields, in short reaction times. Aldol products and carbene‐aldehyde adducts have been obtained in elevated yields from linear and short branched aldehydes, respectively. A comparison with the use of classical organic solvents has been reported     

CO2 adsorption and surface basicity evaluation of aluminophosphate oxynitride (AlPON) catalysts

Aluminophosphate oxynitrides (AlPON) are new catalysts obtained by nitridation of AlPO₄ showing a high surface area and an enhanced surface basicity. In this article, surface basicity is evaluated by CO₂ adsorption and related to the nitrogen content. CO₂ simultaneously adsorbs linearly and as bidentate carbonate and bicarbonate species on AlPON surface. Particularly strong basic centers involving hydroxyls linked to Al cations and in the vicinity of terminal –PNH₂ groups are identified. However, the influence of nitrogen content on surface basicity of AlPON is mostly through the change in the number of sites rather than on the modification of their strength. Activity results obtained for AlPON in base-catalyzed reactions are related with their capability of adsorbing CO₂.     

FTIR studies on the CO,CO2 and H2 co-adsorption over Ru-RuO x /TiO2 catalyst

FTIR spectra of a Ru-RuO_x/TiO₂ catalyst obtained on co-adsorption of CO, CO₂ and H₂ in the temperature range of 300–500 K were found to be the sum total of corresponding spectra observed during methanation of individual oxides. The two oxides compete for metal sites and at each temperature they reacted simultaneously to form distinct transient Ru(CO)_n type species even though the nature, the stability and the reactivity of these species were different in the two cases. The monocarbonyl species formed during adsorption/reaction of CO alone or of CO + H₂ were bonded more strongly than those formed during CO₂ + H₂ reaction.     

Comparison of Ultrasonic and CO(2) Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO(2) laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO(2) laser irradiation. The present work demonstrated that the CO(2) laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO(2) laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO(2) laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.