MPa CO2 Research Articles

Conversion of CO2 with epoxides to cyclic carbonates catalyzed by amino acid ionic liquids at room temperature

CO2 utilization plays an important role in rational use of carbon resources and reduction of carbon emissions. It is still a challenge to achieve efficient CO2 utilization by amino acid ionic liquids (AAILs) under room temperature and atmospheric pressure with cocatalyst- and solvent-free conditions. Herein, the newly developed AAILs including 1,1,3,3-tetramethylguanidine cation ([HTMG]+) together with both amino acid and halogen as anions, were simply synthesized by neutralization reaction. Under mild conditions (30 °C, 20 h and 1 MPa CO2), the cycloaddition reaction of CO2 and propylene oxide could be efficiently catalyzed by [HTMG][His][I] with 99 % propylene carbonate yield and selectivity in the absence of additional solvent and cocatalyst. Notably, even at room temperature and atmospheric pressure for 72 h, [HTMG][His][I] also displayed 96 % yield and 99 % selectivity due to the cooperation of [HTMG]+, [His]2– and [I]–. Meanwhile, [HTMG][His][I] performed excellent universality of various epoxides and reusability. Based on the characterization results of 1H and 13C NMR, it was verified that propylene oxide and CO2 were simultaneously activated by the functional groups in [HTMG][His][I]. Hence, the reaction mechanism for CO2 cycloaddition with epoxide catalyzed by [HTMG][His][I] was proposed. This work provided a simple strategy to prepare sustainable AAILs for efficient CO2 utilization under very mild conditions of room temperature and atmospheric pressure (even the low CO2 concentration at simulated flue gases).

Biocompatible anions-derived ionic liquids a sustainable media for CO2 conversion into quinazoline-2,4(1H,3H)-diones under additive-free conditions

Based on an one-step acid-base neutralization method, several biocompatible anions-derived ionic liquids (bio-AILs) were prepared and characterized. They were first used as dual solvent-catalyst for cyclization of CO2 and 2-aminobenzonitriles to synthesize quinazoline-2,4(1H,3H)-diones. The influence of different bio-AILs structures on the cyclization reaction were studied, and [HTMG][Lae] was confirmed to be an excellent medium. By optimizing the reaction conditions, the [HTMG][Lae]-mediated cyclization reaction could afford a 96 % quinazoline-2,4(1H,3H)-dione yield at 70 °C, 1.0 MPa CO2 pressure for 6 h without other additives. The catalytic activities of various homogeneous media for transformation of CO2 into quinazoline-2,4(1H,3H)-dione were analyzed and compared. In addition, the reusability and general applicability of the [HTMG][Lae] medium were examined, the [HTMG][Lae] could show comparable activity in the fifth experiment, and it had good versatility for cyclization of CO2 with various 2-aminobenzonitriles. Finally, an insight into the activation behaviors of [HTMG][Lae] to reactants were further investigated, and based on this, a feasible reaction mechanism was proposed.

Temperature dependence of carbon deposits within oxide scale on CrMoV steel in atmospheric and supercritical CO2

CrMoV steel was exposed to 500, 550, and 600 °C for up to 120 h in 0.1 and 10 MPa CO2. A significant change in carbon deposition content was not observed in the 0.1 MPa CO2, in contrast to the high carbon content at 550 °C and 10 MPa CO2. The formation of internal Fe-rich M3C carbides and super saturation of steel grains with dissolves carbon at 550 °C but not at 500 and 600 °C may be responsible for this difference. The effect of carbon deposition on the outward Fe diffusion via vacancy or interstitial sites was also discussed.

Selective N-formylation of amines catalysed by Ag NPs festooned over amine functionalized SBA-15 utilizing CO2 as C1 source

N-formylation of amines using CO2 as C1 source has been an uphill transformation in the catalysis research as it involves the utilization of abundant thermodyanamically stable and kinetically inert CO2 to form the N-formylated products, which are potential intermediates for the synthesis of valuable chemicals. Previously various noble as well as non-noble metal nanoparticles have been employed for N-formylation of amines. However, herein for the first time we explored N-formylation reaction under lenient conditions utilizing silver nanoparticles, which are decorated over amine functionalized periodically ordered 2D-hexagonal SBA-15 material, serving as a robust heterogeneous catalyst. The AgNPs@SBA-15-NH2 has been intensively characterized by powder XRD, Brunauer-Emmett-Teller (BET), FEG-TEM, SEM, XPS, TGA, CO2-TPD, FTIR and UV–vis spectroscopic analyses. This supported AgNPs material showed remarkable catalytic activity for N-formylation over a wide range of amines under 0.5 MPa CO2 pressure and at mild temperature (35 °C) conditions. In addition, this AgNPs@SBA-15-NH2 material exhibited high chemical stability and reusability, suggesting its promising future in the CO2 fixation reactions.

Biomethane enhancement from corn straw using anaerobic digestion by-products as pretreatment agents: A highly effective and green strategy

The development of biogas projects feed by lignocellulosic biomass has been constrained by the high cost of pre- and post-treatment. In this study, a novel strategy for pretreatment by using two by-products, i.e., CO2 and liquid digestate (LD), generated from anaerobic digestion (AD) was developed to overcome these shortcomings. Results showed that corn straw pretreated in LD pressurized under 1 Mpa CO2 at 55 ℃ resulted in increased glucose and xylose contents and a 9.80% decrease in cellulose crystallinity. After 45 days of AD conversion, the methane yield increased by 50.97% compared with untreated straw. However, pretreatment in LD pressurized under 1 Mpa CO2 at 170 ℃ produced 5-hydroxymethylfurfural and furfural, which led to a decrease in methane production from the straw in the subsequent AD conversion. The alteration of the microbial community in the pretreated slurry at 55 °C was another potential contributor to the enhanced performance of AD.

Synergetic effect between curing reaction and CO2 diffusion for microcellular epoxy foam preparation in supercritical CO2

Directly rapid depressurization foaming process has been successfully applied to prepare microcellular epoxy foams using supercritical CO2 as blowing agent. It is found that both curing reaction and CO2 diffusion are crucial for controlling cell morphology. For epoxy of tetraglycidyl-4,4′-diaminodiphenyl-methane (TGDDM) and 4,4-diaminodiphenylsulfone (4,4-DDS) system, the experimental and molecular simulation results displayed that higher CO2 pressure always promotes curing reaction, and CO2 diffusion is more sensitive to pressure at low curing degree, while limited by high curing degree. The foaming experimental results showed that there existed a suitable curing degree range, in which both unsaturated CO2 concentration and curing degree contribute to good cell structure. Higher CO2 pressure can broaden this foamable window. The microcellular epoxy foam with an average cell diameter of 14.6 µm and cell density over 109 cells/cm3 as well as volume expansion ratio of 14.5 has been obtained at 85% curing degree under 22 MPa CO2 pressure.

Imidazolium-based deep eutectic solvents as multifunctional catalysts for multisite synergistic activation of epoxides and ambient synthesis of cyclic carbonates

Novel imidazolium-based deep eutectic solvents were facilely synthesized and characterized by TGA, DSC, FT-IR, and NMR techniques. Various imidazolium salts and aromatic compounds containing active hydrogens were applied as HBAs and HBDs respectively for efficient cycloaddition of CO2 with styrene oxide under ambient conditions. The optimized [C1C2Im]I/m-DHB (1-ethyl-3-methylimidazolium iodide/m-dihydroxybenzene) DES with the molar ratio of 2:1 exhibited excellent catalytic activity at room temperature and 0.1 MPa CO2 pressure without cocatalyst, metal, and solvent. Moreover, the effects of reaction parameters, substrate scope, and catalyst recovery were studied in detail. Based on the results, the plausible reaction mechanism on the multisite synergistic activation of the epoxide by the hydrogen bonds involved with both the OH in m-DHB and C2-H in [C1C2Im]I was proposed. Finally, the reaction kinetics was studied and the cycloaddition reaction was accorded with the pseudo-first-order reaction kinetic model.

Cobalt Carbonyls Stabilized by N,P-Ligands: Synthesis, Structure, and Catalytic Property for Ethylene Oxide Hydroalkoxycarbonylation.

Reactions of N,P-Ligands as Ph2 P(o-NMe2 C6 H4 ) (1 L), 2,6-iPr2 C6 H3 NHC(Ph)=NC6 H4 (o-PPh2 ) (2 L), and Ph2 PN(R)PPh2 (R=iPr (3 L), cyclo-C6 H11 (4 L), tBu (5 L), CH2 C4 H7 O (6 L)) each with dicobalt octacarbonyl produced complexes [1 LCo(CO)3 ]2 (1), [2 LCo(CO)(μ-CO)2 Co(CO)3 ] (2), [3 LCo(CO)3 ]+ [Co(CO)4 ]- (3), [3 LCo(CO)2 ]2 (4), [4 LCo(CO)2 ]2 (5), [5 LCo(CO)2 ]+ [Co(CO)4 ]- (6), and [6 LCo(CO)2 ]+ [Co(CO)4 ]- (7). Complexes 1-7 have all been structurally characterized by X-ray crystallography, IR and NMR spectroscopies, and elemental analysis. Catalytic tests on transformation of ethylene oxide (EO), CO and MeOH into methyl 3-hydroxypropionate (3-HMP) indicate that complexes 1-7 are active, where ion-pair complexes 3 and 6-7 behave more excellently (by achieving 88.4-93.6% 3-HMP yields) than the neutral species 1-2 and 4-5 (35.0-46.5% 3-HMP yields) when the reactions are all operated at 2 MPa CO pressure and 50 °C in MeOH solvent. Density functional theory (DFT) study by selecting 3 as a model suggests a cooperative catalytic reaction mechanism by [Co(CO)4 ]- and its counter cation [3 LCo(CO)3 ]+ . The cobalt-homonuclear ion-pair catalyzed hydroalkoxycarbonylation of EO is present herein.

Experimental Study of Prefabricated Crack Propagation in Coal Briquettes under the Action of a CO2 Gas Explosion.

CO2 deep-hole presplit explosions are an important technology for enhancing gas drainage in low-permeability coal seams. In the process of a CO2 gas explosion, the initial burst crack generated by the shock wave expands the crack tip under the splitting action of high-pressure CO2 gas. To explore the effects of CO2 gas explosions on crack tips, we constructed an analytical model of gas pressure attenuation at different positions based on fluid motion equations, proposed equations for crack opening and growth rates, and inverted the energy field of the whole process of CO2 blasting. We used a test platform for the independent development of CO2 gas explosions under experimental conditions of 1 MPa axial pressure and 2 MPa CO2 gas pressure and a VIC-3D measurement system. We conducted the gas explosion experiments on prefabricated cracked samples with a crack length of 10 mm and width of 0.2 mm to analyze the dynamic response of the crack tip. The results showed that there were three stages in the propagation of a prefabricated crack under the action of a CO2 gas explosion. The first stage, from 0 to 290 ms, included energy storage at the crack tip and a maximum opening rate increment of 0.0043 m/s. The second stage, from 291 to 295 ms, was rapid crack propagation with maximum opening rate increment and propagation rates of 0.1865 and 5.35 m/s, respectively. In the third stage, from 296 to 309 ms, the crack tip propagated slowly, the maximum opening rate increment and growth rates were 0.0969 and 5.81 m/s, respectively, and the crack arrest coordinates were 4.57 and 35.28 mm. The experimental study verified the accuracy of the calculation model, proved that CO2 gas promotes the growth of crack tips, explained the spatiotemporal evolution mechanism of the CO2 explosion process, and provided experimental support for subsequent research related to explosions.

One-pot synthesis of pyridine-based ionic hyper-cross-linked polymers with hierarchical pores for efficient CO2 capture and catalytic conversion

A kind of pyridine-based ionic hyper-cross-linked polymers (Py-HCP-X, X = Cl, Br) with high surface area, plentiful hierarchical pores and abundant catalytic active units were prepared via a one-pot method. Adsorption measurements showed that the as-prepared Py-HCP-X exhibited high CO2 capture capacity (up to 1.72 mmol g−1, 273 K and 1 bar). Importantly, Py-HCP-Br displayed excellent catalytic activity for the cycloaddition of CO2 to epoxides under metal/cocatalyst/solvent-free conditions. And the propylene carbonate was produced in 97% yield with an excellent selectivity of 99% at 120 °C and 2.0 MPa CO2 for 8 h. The high performance of the present catalyst is ascribable to synergistic contributions of plentiful hierarchical pores and abundant nucleophilic bromide ions and pyridine-based active units in the Py-HCP-Br catalyst. Additionally, the catalyst is able to be simply separated by centrifugation and reused for four runs without significant loss in the performance, furthermore, the catalyst exhibits great structural stability and substrate universality.

Quaternary ammonium salt functionalized MIL-101-NH2(Cr) as a bifunctional catalyst for the cycloaddition of CO2 with epoxides to produce cyclic carbonates

The reaction of CO2 with epoxides to produce cyclic carbonates requires high-performance, low-cost, and facilely recycled catalysts. Here, we report a heterogeneous catalyst (MIL-101-N(Bnme2)Br) based on metal-organic frameworks (MOFs) for catalytic CO2 conversion into cyclic carbonates. The MIL-101-N(Bnme2)Br catalyst was prepared as follows: A MOFs precursor (MIL-101-NH2) was firstly synthesized using a method of hydrothermal synthesis, then coupled with the quaternary ammonium salt ionic liquid (N(BzBnme2)Br) via aldehyde-amide condensation. A series of comparative experiments revealed that MIL-101-N(Bnme2)Br catalyst has high activity for catalyzing the cycloaddition reaction to produce cyclic carbonates in the absence of solvents and co-catalysts. As was exampled by the synthesis of propylene carbonate, a high yield (93 %) and selectivity (99 %) was achieved under the optimized conditions (0.93 mol% MIL-101-N(Bnme2)Br catalyst, 1.4 MPa CO2 pressure, 17 mmol propylene oxide, 100 °C, 5 h). More impressive, the MIL-101-N(Bnme2)Br catalyst could be recycled easily by filtration and was reusable up to several times without a significant activity decay. Furthermore, our density functional theory (DFT) calculations suggested that such high catalytic activity mainly resulted from the cooperative catalysis between the coordinatively unsaturated Cr3+ sites and Br anions in MIL-101-N(Bnme2)Br catalyst. Meanwhile, a possible mechanism for the cycloaddition reaction catalyzed by MIL-101-N(Bnme2)Br catalyst was also proposed.

Elicitation of phenylpropanoids in maqui (Aristotelia chilensis [Mol.] Stuntz) plants micropropagated in photomixotrophic temporary immersion bioreactors (TIBs)

A biotechnological system for the production of plants biomass and phenylpropanoids of maqui was developed in photomixotrophic TIBs. The in vitro maqui multiplication was evaluated using combinations of TDZ and BAP in TIBs 1L capacity. Treatment of MS basal supplemented with TDZ 1 mg/L shows the best results for the variables fresh weight and multiplication rate. Photomixotrophic conditions were standardized in media with 3%, 2%, 1%, 0% sucrose at a light intensity of 100 µM m−2 s−1. The treatments reduced in sucrose (1 and 2%) and air supplemented with 0.4 MPa CO2 do not differ significantly in biomass production (fresh weight per cluster of plants) compared to the control treatment with sucrose 3% and standard air. Treatment with ABA (1 m/l) induced the production and accumulation of phenylpropanoids metabolites in maqui cultures bioreactors. Phenylpropanoids in in vitro biomass of maqui and culture medium from TIBs were determined in parallel with control samples from wild plants and mature fruits. After the third day of analysis, not significant differences in polyphenols and anthocyanin contents were verified between the treatments of maqui in TIBs + ABA and controls. The non-significant differences in the contents of polyphenols and anthocyanin were maintained until the 15 days of analysis. The antioxidant capacity comparing samples of maqui in bioreactors and wild plants showed no significant differences by the ORAC test from day 5 to day 15 of the study. Results originate an optimized methodology that was scale to SETIS™ bioreactors of 5L capacity. For the first time maqui micropropagation has been established in TIBs followed by elicitation of phenylpropanoids metabolites. Contents of metabolites from maqui in TIBs do not differ from those of wild fruits, while antioxidant capacity of phenylpropanoids was preserved during the study.

Reaction kinetics and phase behavior in the chemoselective hydrogenation of 3-nitrostyrene over Co-N-C single-atom catalyst in compressed CO2

Single-atom catalysts (SACs) have demonstrated excellent performances in chemoselective hydrogenation reactions. However, the employment of precious metals and/or organic solvents compromises their sustainability. Herein, we for the first time report the chemoselective hydrogenation of 3-nitrostyrene over noble-metal-free Co-N-C SAC in green solvent — compressed CO2. An interesting inverted V-curve relation is observed between the catalytic activity and CO2 pressure, where the conversion of 3-nitrostyrene reaches the maximum of 100% at 5.0 MPa CO2 (total pressure of 8.1 MPa). Meanwhile, the selectivities to 3-vinylaniline at all pressures remain high (> 99%). Phase behavior studies reveal that, in sharp contrast with the single phase which is formed at total pressure above 10.8 MPa, bi-phase composed of CO2/H2 gas-rich phase and CO2-expanded substrate liquid phase forms at total pressure of 8.1 MPa, which dramatically changes the reaction kinetics of the catalytic system. The reaction order with respect to H2 pressure decreases from ~0.5 to zero at total pressure of 8.1 MPa, suggesting the dissolved CO2 in 3-nitrostyrene greatly promotes the dissolution of H2 in the substrate, which is responsible for the high catalytic activity at the peak of the inverted V-curve.

Insight into the Influence of Properties of Poly(Ethylene-co-octene) with Different Chain Structures on Their Cell Morphology and Dimensional Stability Foamed by Supercritical CO2.

Poly(ethylene-co-octene) (POE) elastomers with different copolymer compositions and molecular weight exhibit quite distinctive foaming behaviors and dimensional stability using supercritical carbon dioxide (CO2) as a blowing agent. As the octene content decreases from 16.54% to 4.48% with constant melting index of 1, both the melting point and crystallinity of POE increase, due to the increase in fraction of ethylene homo-polymerization segment. the foaming window of POE moves to a narrow higher temperature zone from 20–50 °C to 90–110 °C under 11 Mpa CO2 pressure, and CO2 solubility as well as CO2 desorption rate decrease, so that the average cell diameter becomes larger. POE foams with higher octene content have more serious shrinkage problem due to lower compression modulus, weaker crystal structure and higher CO2 permeability. As POE molecular weight increases at similar octene content, there is little effect on crystallization and CO2 diffusion behavior, the foaming window becomes wider and cell density increases, mainly owing to higher polymer melt strength, the volume shrinkage ratio of their foams is less than 20% because of similar higher polymer modulus. In addition, when the initiate expansion ratio is over 17 times, POE foams with longer and thinner cell wall structures are more prone to shrinkage and recovery during aging process, due to more bending deformation and less compression deformation.

Effect of alcohols-regulated crystallization on foaming process and cell morphology of polypropylene

A novel approach was established to promote favorable PP foams at low temperatures by regulating the melt crystallization behavior. The crystallization behavior of PP on supercritical CO2 foaming was systematically studied in the presence of alcohol as co-blowing agent. The results of dissipative particle dynamics (DPD) simulations revealed that the diffusion coefficient of blowing agents in PP was enhanced with the increase of alcohol molecular weight. Alcohols had a significant effect on the melt and crystallization behavior of PP. The crystallization temperature was decreased from 88 ℃ to 82 ℃, and crystallinity declined from 17% to 9% by adding 1-decanol in 8 MPa CO2. The addition of co-blowing agents decelerated desorption rate of blowing agents. The lower limit of foaming temperature moved further down with the carbon chain growth of alcohol, e.g., the lower temperature decreased from 145 ℃ to 130 ℃ by adding 1-decanol.

Effect of Carbon Dioxide on Paraffinic Bitumen Froth Treatment: Asphaltene Precipitation from a Commercial Bitumen Froth Sample.

In this study, the effect of carbon dioxide in assisting paraffinic bitumen froth treatment was investigated. The work was divided into two parts, the effect of water addition on CO2-assisted asphaltene precipitation from a dry and clean bitumen sample by n-heptane and the effect of CO2 injection to a mixture of n-heptane and a commercial bitumen froth sample. It was found that water addition to the dry and clean bitumen improved the beneficial effect of CO2 on promoting asphaltene precipitation by n-heptane, where asphaltene precipitation increased by 2.5 percentage points (or 19%) with the presence of water and CO2. The asphaltene precipitation enhancement may be due to chemical reactions between injected CO2 and water in the formation of carbonic acid in the aqueous phase, which destabilized asphaltene. On the other hand, no improvement was detected under the control tests (N2). Similar results were observed in the case of CO2 injection to paraffinic solvent (n-heptane) treatment of the commercial bitumen froth sample. The results indicated that when the commercial bitumen froth sample was mixed with n-heptane at a solvent/bitumen ratio of 1.08, the injection of 1.7 MPa CO2 increased the amount of precipitated asphaltene from 10.0 ± 0.1% (without CO2) to 15.2 ± 0.2% (with 1.7 MPa CO2) at 90 °C, indicating a potential reduction of solvent usage by about 66%.

Normalization of the power-law rate equation for determining the kinetic parameters of the char-CO2 reaction

The power-law (or nth-order) rate equation is the most commonly used model to describe the kinetics of the char−CO2 reaction, which consists of three major kinetic parameters: the activation energy (E), the pre-exponential factor (A0), and the reaction order (n). So far, the temperature dependence of the reaction order and its influence on determining kinetic parameters have not attracted enough attention. This paper specially addresses the impact of the CO2 partial pressure on the reaction kinetics. CO2 gasification of the lignite char and coffee grounds char is conducted via thermogravimetry analysis (TGA) at 1098–1173 K and 0.025–0.05 MPa CO2 partial pressure. An exploration is made to normalize the power-law rate equation for kinetic computation, and pressure-independent E and A0 are obtained. Findings and insights obtained in this study can offer reliable evaluation of kinetic parameters and comparability of different kinetic studies.

Development and Evaluation of Cocoa Butter Taste Masked Ibuprofen Using Supercritical Carbon Dioxide.

Masking the unpleasant taste of the pharmaceutically active ingredients plays a critical role in patient acceptance, particularly for children. This work's primary objective was the preparation of taste-masked ibuprofen microparticles using cocoa butter with the assistance of supercritical fluid technology. Microparticles were prepared by dissolving ibuprofen in melted cocoa butter at 40 °C. The solution was then introduced into a supercritical fluid unit and processed at 10 MPa CO2 pressure for 30 min. The product was collected after depressurizing the system. The effect of the drug to cocoa butter ratio and the supercritical fluid units' configuration on product quality was evaluated and compared with the sample prepared by a conventional method. Physicochemical characterization of the prepared product, including particle size, crystallinity, entrapment efficiency, in vitro drug release, and product taste using a human volunteer panel was conducted. The produced microparticles were in the range of 1.42 to 15.28 μm. The entrapment efficiency of the formulated microparticles ranged from 66 to 81%. The drug:polymer ratio, the configuration of the supercritical fluid unit, and the method of preparation were found to have a critical role in the formulation of ibuprofen microparticles. Taste evaluation using human volunteers showed that microparticles containing 20% drug and processed with supercritical fluid technology were capable of masking the bitter taste of ibuprofen. In conclusion, the dispersion of ibuprofen in cocoa butter using supercritical fluid technology is a a promising innovative method to mask the bitter taste of ibuprofen.

Control of pore-size distribution on CO2 adsorption volume and kinetics in Gondwana coals: Implications for shallow-depth CO2 sequestration potential

We report experimental CO2 adsorption isotherms and diffusion-related parameters of fresh coal samples from Jharia (350–360 m) and South Karanpura (50–60 m) coalfields, India at three different temperatures (28, 35 and 45 °C) and up to 4 MPa CO2 pressures. The results confirm that temperature possesses an inverse relationship with the excess adsorption volume. Data modelling with the Langmuir and Dubinin-Radushkevich (D-R) equations show the D-R equation better predicts the experimental excess adsorption data. A conversion of the excess adsorbed volume to absolute adsorption further reveals that the modified D-R equation is even a better model to estimate absolute adsorption than the conventional D-R equation. Adsorption kinetics data indicate that temperature has a positive influence on the adsorption rate. We determined the diffusion coefficients of CO2 in these coals using the unipore model, which suggest that it increases with pressure and temperature. Effective diffusivity and diffusion-time maintain a direct and inverse relationship, respectively, with the elevation of temperature. The experimental adsorbed volume and kinetics data are correlated with the corresponding pore-size distribution of the samples. Shallow depth South Karanpura samples have lower average pore diameter, higher volumetric proportion of micropores and surface area compared to those of higher depth Jharia coal samples. Lower adsorption volume and sluggish adsorption kinetics in Jharia coals result from a small surface area and relatively sparse distribution of semi open-ended micropores with poor interconnection. Based on our experimental observations, we discuss and suggest the potential and possible conditions for CO2 sequestration in the Permian Gondwana coalfields, India.

One-step preparation of ammonium-specified pyrazolium ionic liquids unveil the more popular pathway for the CO2 fixation: Integrated experimental and theoretical studies

Amino-specified pyrazolium ionic liquid (APEPzBr) is synthesized by two steps. It is interesting that the product of the first step ([EPzPNH3]Br2) could also catalyze the coupling reaction of carbon dioxide (CO2) and epoxides under 70 °C along with 0.5 MPa CO2 pressure, which is even more benign than APEPzBr. It is attributed to the strong ability of [EPzPNH3]Br2 to absorb CO2 along with robust electrophilic activation, which is testified by density functional theory and 13C NMR measurement. The difference between [EPzPNH3]Br2 and APEPzBr is further elucidated by electron localization function (ELF) and atoms in molecules (AIM).