Solubility Of N2 Research Articles

Predicting the solubility of CO2 and N2 in ionic liquids based on COSMO-RS and machine learning.

As ionic liquids (ILs) continue to be prepared, there is a growing need to develop theoretical methods for predicting the properties of ILs, such as gas solubility. In this work, different strategies were employed to obtain the solubility of CO2 and N2, where a conductor-like screening model for real solvents (COSMO-RS) was used as the basis. First, experimental data on the solubility of CO2 and N2 in ILs were collected. Then, the solubility of CO2 and N2 in ILs was predicted using COSMO-RS based on the structures of cations, anions, and gases. To further improve the performance of COSMO-RS, two options were used, i.e., the polynomial expression to correct the COSMO-RS results and the combination of COSMO-RS and machine learning algorithms (eXtreme Gradient Boosting, XGBoost) to develop a hybrid model. The results show that the COSMO-RS with correction can significantly improve the prediction of CO2 solubility, and the corresponding average absolute relative deviation (AARD) is decreased from 43.4% to 11.9%. In contrast, such an option cannot improve that of the N2 dataset. Instead, the results obtained from coupling machine learning algorithms with the COSMO-RS model agree well with the experimental results, with an AARD of 0.94% for the solubility of CO2 and an average absolute deviation (AAD) of 0.15% for the solubility of N2.

Localized High-Concentration Electrolyte in Li-Mediated Nitrogen Reduction for Ammonia Synthesis.

The lithium-mediated nitrogen reduction reaction (Li-NRR) is a promising green alternative to the Haber-Bosch process for ammonia synthesis. The solid electrolyte interphase (SEI) is crucial for high efficiency and stability, as it regulates reactant diffusion and suppresses side reactions. The SEI properties are greatly influenced by the Li+ ion solvation structure, which is controllable through electrolyte engineering. Although anion-derived SEI enhances selectivity and stability, it has typically been engineered using high-concentration electrolytes (HCEs), which face mass transfer, viscosity, and cost issues. In this study, a localized high-concentration electrolyte (LHCE) in the Li-NRR is first introduced, enabling the formation of anion-derived SEI in a low-concentration electrolyte (LCE) by enhancing the Li-anion coordination using an antisolvent. Among various antisolvents, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) achieves the highest ammonia Faradaic efficiency (73.6 ± 2.5%), more than double that of the LCE (34.3 ± 2.8%) and exceeding the HCE (56.0 ± 2.8%). Systematic calculations and experimental analyses show that the LHCE exhibits anion-rich solvation structures and formsthin, inorganic SEI. Moreover, the LHCE has advantages of low viscosity and high N2 solubility, which facilitate mass transport. This study suggests the application of LHCE as an effective electrolyte engineering strategy to enhance the Li-NRR efficiency.

Exploring the Effect of Ionic Liquid Conformation on the Selective CO2 Capture of Supported Ionic Liquid-Phase Adsorbents Based on ZIFs.

The CO2 adsorption capacity and the CO2/N2 selectivity of a series of Supported Ionic Liquid-Phase adsorbents (SILPs), including the novel inversely structured SILP "Inverse SILPs", are thoroughly investigated. ZIF-8, ZIF-69 and ZIF-70 were involved as the solid matrix, while ILs, having tricyanomethanide (TCM) as an anion and alkyl-methylimidazolium of different alkyl chain lengths (C2, C6, C8) as a cation, were used as the liquid constituents of the SILPs. The ultimate target of the work was to ratify a few recently reported cases of enhanced CO2 absorptivity in ILs due to their incorporation in ZIFs and to corroborate phenomena of CO2/N2 selectivity improvements in ZIFs, due to the presence of ILs. This ambiguity originates from the vague assumption that the pores of the ZIF are filled with the IL phase, and the free pore volume of a SILP is almost zero. Yet, through the integration of theoretical predictions with N2 porosimetry analysis of an actual sample, it is suggested that a thin layer of IL covered the exterior surface of a ZIF crystal. This layer could act as an impermeable barrier for N2, inhibiting the gas molecules from reaching the empty cavities laying underneath the liquid film during porosimetry analysis. This consideration is based on the fact that the solubility of N2 in the IL is very low, and the diffusivity at 77 K is negligible. In this context, the observed result reflects an averaged adsorptivity of both the IL phase and the empty pores of the ZIF. Therefore, it is incorrect to attribute the adsorption capacity of the SILP solely to the mass of the IL that 'hypothetically' nests inside the pore cavities. In fact, the CO2 adsorption capacity of SILPs is always less than the average adsorptivity of an ideal ZIF/IL mixture, where the two phases do not interact. This reduction occurs because some ZIF pores may become inaccessible, particularly when the IL forms a layer on the pore walls, leaving only a small empty core accessible to CO2 molecules. Additionally, the IL layer masks the active sites on the ZIF's pore walls. It should also be noted that the CO2/N2 selectivity increases only when the ZIF's pores are completely filled with the IL phase. This is because ILs have a higher CO2/N2 selectivity compared to the bare ZIF.

Effect of CO2 Concentration on the Performance of Polymer-Enhanced Foam at the Steam Front.

This study examines the impact of CO2 concentration on the stability and plugging performance of polymer-enhanced foam (PEF) under high-temperature and high-pressure conditions representative of the steam front in heavy oil reservoirs. Bulk foam experiments were conducted to analyze the foam performance, interfacial properties, and rheological behavior of CHSB surfactant and Z364 polymer in different CO2 and N2 gas environments. Additionally, core flooding experiments were performed to investigate the plugging performance of PEF in porous media and the factors influencing it. The results indicate that a reduction in CO2 concentration in the foam, due to the lower solubility of N2 in water and the reduced permeability of the liquid film, enhances foam stability and flow resistance in porous media. The addition of polymers was found to significantly improve the stability of the liquid film and the flow viscosity of the foam, particularly under high-temperature conditions, effectively mitigating the foam strength degradation caused by CO2 dissolution. However, at 200 °C, a notable decrease in foam stability and a sharp reduction in the resistance factor were observed. Overall, the study elucidates the effects of gas type, temperature, and polymer concentration on the flow and plugging performance of PEF in porous media, providing reference for fluid mobility control at the steam front in heavy oil recovery.

Hydrated molten salt electrolytes effectively promote electrocatalytic NH3 synthesis at low temperatures

In the field of electrocatalytic nitrogen reduction reaction (NRR), molten salt is used as a unique electrolyte due to its advantages of high N2 solubility and wide electrochemical window. However, it has failed to be widely used due to its high reaction temperature (mostly > 200 °C) and low yield. Herein, a novel low-temperature (<100 °C) electrolysis system with hydrated molten salt hybrid electrolyte is designed. This system exhibits an ammonia yield of 1.003 × 10−8 mol s−1 cm−2 (−0.7 V vs. SCE) at 60 °C. Faradaic efficiency (FE) reaches 80.45 % (−0.65 V vs. SCE). The NH3 yield and FE are increased by 18.6 and 2 times compared to the previously reported low-temperature system, respectively. Linear sweep voltammetry (LSV), in situ Raman and in situ Fourier Transform-Infrared (FT-IR) experiments show that solid crystalline water can be used as a hydrogen source to effectively promote NRR while inhibiting the hydrogen evolution reaction (HER). Molecular dynamics (MD) experiments confirm that the electrolyte system maintains a high N2 solubility and mass transfer rate.

Dissociation line and driving force for nucleation of the nitrogen hydrate from computer simulation. II. Effect of multiple occupancy.

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. This work is the natural extension of Paper I, in which the dissociation temperature of the N2 hydrate has been obtained at 500, 1000, and 1500bar [Algaba et al., J. Chem. Phys. 159, 224707 (2023)] using the solubility method and assuming single occupancy. We extend our previous study and determine the dissociation temperature of the N2 hydrate at different pressures, from 500 to 4500bar, taking into account the single and double occupancy of the N2 molecules in the hydrate structure. We calculate the solubility of N2 in the aqueous solution as a function of temperature when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase with single and double occupancy via planar interfaces. Both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We observe a negligible effect of occupancy on the dissociation temperature. Our findings are in very good agreement with the experimental data taken from the literature. We have also obtained the driving force for the nucleation of the hydrate as a function of temperature and occupancy at several pressures. As in the case of the dissociation line, the effect of occupancy on the driving force for nucleation is negligible. To the best of our knowledge, this is the first time that the effect of the occupancy on the driving force for nucleation of a hydrate that exhibits sII crystallographic structure is studied from computer simulation.

Fluorine Domains Induced Ultrahigh Nitrogen Solubility in Ionic Liquids.

Fluorinated ionic liquids (ILs) are well-known as electrolytes in the nitrogen (N2) electroreduction reaction due to their exceptional gas solubility. However, the influence of fluorinated functional group on N2 solvation and solubility enhancement remains unclear. Massive molecular dynamics simulations and free energy perturbation methods are conducted to investigate the N2 solubility in 11 traditional and 9 fluorinated ILs. It shows that the fluorinated IL of 1-Ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([Emim]FAP) exhibits ultrahigh solubility, 4.844 × 10-3, approximately 118 times higher than that of traditional IL 1-Ethyl-3-methylimidazolium nitrate ([Emim]NO3). Moreover, fluorinated ILs with more than 10 C-F bonds possess higher N2 solubility than others and show an exothermic nature during solvation. As the C-F bonds number in ILs decreases, the N2 solubility decreases significantly and displays the opposite endothermic behavior. To understand the ultrahigh N2 solubility in fluorinated ILs, we propose a concept of fluorine densification energy (FDE), referring to the average strength of interaction between atoms per unit volume in ILs with fluorine domains, demonstrating a linear relationship with C-F bonds. Physically, lower FDE results in lower N2-anion pair dissociation energy and higher free volume, finally enhancing the N2 solubility. Consequently, medium to long alkyl fluorine tails within a polar environment defines a distinct fluorine domain, emphasizing FDE's role in enhancing N2 solubility. Overall, these quantitative results will not only deepen the understanding of N2 solvation in ILs but may also shed light on the rational design of IL-based high-performance N2 capture and conversion technologies.

Engineered Electron-Deficient Sites at Boron-Doped Strontium Titanate/Electrolyte Interfaces Accelerate the Electrocatalytic Reduction of N2 to NH3: A Combined DFT and Experimental Electrocatalysis Study.

The development of an efficient, selective, and durable catalysis system for the electrocatalytic N2 reduction reaction (ENRR) is a promising strategy for the sustainable production of ammonia. The high-performance ENRR is limited by two major challenges: poor adsorption of N2 over the catalyst surface and abysmal N2 solubility in aqueous electrolytes. Herein, with the help of our combined density functional theory (DFT) calculations and experimental electrocatalysis study, we demonstrate that concurrently induced electron-deficient Lewis acid sites in an electrocatalyst and in an electrolyte medium can significantly boost the ENRR performance. The DFT calculations, ex situ X-ray photoelectron and FTIR spectroscopy, electrochemical measurements, and N2-TPD (temperature-programmed desorption) over boron-doped strontium titanate (BSTO) samples reveal that the Lewis acid-base interactions of N2 synergistically enhance the adsorption and activation of N2. Besides, the B-dopant induces the defect sites (oxygen vacancies and Ti3+) that assist in enhanced N2 adsorption and results in suppressed hydrogen evolution due to B-induced electron-deficient sites for H+ adsorption. The insights from the DFT study evince that B prefers the Srtop position (on top of Sr) where N2 adsorbs in an end-on configuration, which favors the associative alternating pathway and suppresses the competitive hydrogen evolution. Thus, our combined experimental and DFT study demonstrates an insight toward enhancing the ENRR performance along with the suppressed hydrogen evolution via concurrently engineered electron-deficient sites at electrode and electrolyte interfaces.

Interfacial Engineering Boosting the Activity and Stability of MIL-53(Fe) toward Electrocatalytic Nitrogen Reduction.

The electrochemical nitrogen reduction reaction (eNRR) has emerged as a promising strategy for green ammonia synthesis. However, it suffers unsatisfactory reaction performance owing to the low aqueous solubility of N2 in aqueous solution, the high dissociation energy of N≡N, and the unavoidable competing hydrogen evolution reaction (HER). Herein, a MIL-53(Fe)@TiO2 catalyst is designed and synthesized for highly efficient eNRR. Relative to simple MIL-53(Fe), MIL-53(Fe)@TiO2 achieves a 2-fold enhancement in the Faradaic efficiency (FE) with an improved ammonia yield rate by 76.5% at -0.1 V versus reversible hydrogen electrode (RHE). After four cycles of electrocatalysis, MIL-53(Fe)@TiO2 can maintain a good catalytic activity, while MIL-53(Fe) exhibits a significant decrease in the NH3 yield rate and FE by 79.8 and 82.3%, respectively. Benefiting from the synergetic effect between TiO2 and MIL-53(Fe) in the composites, Fe3+ ions can be greatly stabilized in MIL-53(Fe) during the eNRR process, which greatly hinders the catalyst deactivation caused by the electrochemical reduction of Fe3+ ions. Further, the charge transfer ability in the interface of composites can be improved, and thus, the eNRR activity is significantly boosted. These findings provide a promising insight into the preparation of efficient composite electrocatalysts.

Aqueous Nitrogen-Nanobubble dispersion and supersaturation at elevated pressures up to 277 bara

Aqueous nanobubble (NB) dispersion of gaseous species has been studied and applied for various processes near atmospheric pressure, but its fundamental properties are not well understood at elevated pressures. This paper presents an experimental program that measures the gas content of aqueous NB dispersion of nitrogen (N2) at pressures up to 277 bara. The parameters directly set in the experiments were temperature, external pressure, and total volume while the overall composition of aqueous NB dispersion was obtained by constant mass expansion with material balance. The experimental data were analyzed by using a thermodynamic model for calculating an internally consistent set of properties at the experimental conditions.Results show that the N2 content in aqueous NB dispersion increased significantly with the system pressure. For example, the N2 content at 277 bara was 0.29 mol/L for aqueous NB dispersion with deionized (DI) water, which was 2.3 times greater than the inherent solubility of N2 in DI water at the same pressure. The effect of salinity was studied by using 0.88 M NaCl brine in place of DI water, but the N2 contents were similar to those with DI water for the pressures tested in this research. Application of a thermodynamic model using the GERG-2008 equation of state to the experimental data indicates that NBs themselves were unlikely the main storage of N2, but the existence of NBs enabled the supersaturation of the aqueous phase by N2 because of capillary pressure.

Highly selective capture of sulfur dioxide by low viscosity 1,2,4-triazole + [Emim]Cl deep eutectic solvents

Sulfur dioxide (SO2) is a toxic gas emitted from industrial waste gases, and its removal is crucial to improve the quality of the atmosphere and reduce the harm to human health. In this work, we investigated the absorption of SO2 by deep eutectic solvents (DESs) with low viscosity 1,2,4-triazole (Trtz) and 1-ethyl-3-methylimidazole chloride ([Emim]Cl) under different conditions. We briefly investigated the mechanism of sulfur dioxide absorption by DESs and measured the absorption performance of Trtz + [Emim]Cl DESs for SO2 at different molar ratios. The experimental results show that all Trtz + [Emim]Cl DESs have good capture performance for SO2, among which 298.2 K Trtz + [Emim]Cl (1:3) DES has an absorption capacity of 18.15 mol/kg (102.2 kPa) for SO2, surpassing most previously reported deep eutectic solvents. We found that the solubility of CO2 and N2 is much lower than that of SO2. The absorption capacity of DESs for SO2 is about 452 times that of CO2 and 1530 times that of N2.Therefore, this absorbent has extensive application prospects in the field of SO2 gas capture.

Efficient Synthesis of Nitric Acid Under Air Atmosphere with Lattice-Confined Ru Clusters

Nitrate (NO3 -) is an important industrial chemical used as fertilizers in agriculture, as well as oxidizing agents in explosives. Today, NO3 - is manufactured predominantly via an Ostwald process by oxidizing ammonia (NH3), and the ammonia used here comes primarily from the Haber–Bosch (HB) process.However, this process operates at high temperatures (300–500 °C) and pressures (200–300 bar), and requires a coupled steam reforming plant for hydrogen (H2) production. As a result, approximately 1.9 metric tons of CO2 is formed per metric ton of NH3 produced, contributing significantly to climate change. In addition, due to the complexity of the Ostwald and Haber-Bosch processes, it is only economical at large scales, leading to centralized production, which situation is poorly matched with the distributed nature of HNO3 utilization. Therefore, it is highly desirable to bypass the ammonia route and develop a direct and sustainable approach for HNO3 synthesis.Electrochemical synthesis of chemicals has been regarded as an attractive alternative to traditional thermochemical methods. In electrochemical reactions, electric potential can replace high temperature and pressure as the thermodynamic driving force.Therefore, direct electrochemical oxidation of molecular nitrogen appears to be a very potential approach for HNO3 synthesis,which could be sustainable, modular and easily integrated with intermittent renewable electricity. However, due to the lack of natural or artificial electrocatalysts as a reference, the nitrogen oxidation reaction (NOR) remains largely unexplored despite its enormous practical value as a replacement for the fossil fuel-driven two-step HNO3 preparation approach.Until 2019, Zhang et al. reported the first experimental NOR electrocatalyst composed of well-dispersed Pd nanoparticles on MXene nanosheets that can effectively convert N2 into nitrate, which definitely proved the feasibility of using electrochemistry to motivate the endothermic NOR at ambient conditions. Unfortunately, to date, there are still only a few works that reported the electrosynthesis of nitrate from nitrogen, and the proposed electrocatalysts can only achieve limited NOR activity.An in-depth exploration of the NOR process, which consists of two main steps: the first step is a rate-limiting step that converts inert N2 into the active NO* intermediate; the second step is a nonelectrochemical step where NO* reacts with H2O and the generated O* from electrocatalytic water splitting to form nitrate. Therefore, the main factors restricting the development of the electrochemical nitrate synthesis technology can be inferred as follows: (1) the strong N≡N triple bond in the dinitrogen molecule (bond energy: 940.95 kJ mol−1) is highly challenging to oxidate nitrogen to nitrate under mild conditions; (2) the potential window between the NOR and oxidation evolution reaction (OER) is quite narrow, and thus the latter as a competitive reaction can severely restrict the selectively of the nitrogen oxidation synthesis of nitrate; (3) the extremely low solubility and diffusion coefficient of N2 in aqueous electrolytes can significantly inhibit the nitrogen available for the reaction, resulting in unfavorable NOR performance. Therefore, to overcome the above obstacles, extensive studies should focus on designing efficient nitrogen oxidation catalysts and improving electrochemical reaction systems to promote NOR and suppress OER.In the present work, we firstly discovered that synthesizing Ru particles grow along the TiO2 lattice (Ru-TiO2) as the working electrode and can achieve excellent NOR performance by using air as a gas source. Textural analysis sufficiently demonstrates that the matching lattice constants of metal Ru and TiO2 allow the Ru to be confined in the TiO2 lattice, leading to the formation of Ru-Ti bonds and the transfer of electrons from TiO2 to Ru metal. Our results reveal that the electron redistribution of Ru-TiO2 can significantly alter the electronic structure of Ru, leading to the formation of highly occupied Ru 4d bands, which can effectively change the adsorption of surface species and improve the NOR activity. In addition, the Ru confined in TiO2 exhibits particularly high stability towards NOR up to potentials above 1.7 V (versus RHE). As a result, Ru-TiO2 could achieve a record-high NOR performance with a nitric acid yield rate of 18.71 ug h-1 cm-2 (150.2 μmol h-1 g-1) and Faraday efficiency of 25.17% in the air atmosphere. This discovery suggests that the surface oxophilicity and electronic structure of metal particles can be effectively modified by lattice confinement in semiconductors and offers an alternative concept for designing catalysts with unique properties for use in catalysis and beyond. Figure 1

Dissociation line and driving force for nucleation of the nitrogen hydrate from computer simulation

In this work, we determine the dissociation line of the nitrogen (N2) hydrate by computer simulation using the TIP4P/Ice model for water and the TraPPE force field for N2. We use the solubility method proposed recently by some of us to evaluate the dissociation temperature of the hydrate at different pressures, from 500 to 1500 bar. Particularly, we calculate the solubility of N2 in the aqueous solution when it is in contact with a N2-rich liquid phase and when in contact with the hydrate phase via planar interfaces as functions of temperature. Since the solubility of N2 decreases with temperature in the first case and increases with temperature in the second case, both curves intersect at a certain temperature that determines the dissociation temperature at a given pressure. We find a good agreement between the predictions obtained in this work and the experimental data taken from the literature in the range of pressures considered in this work. From our knowledge of the solubility curves of N2 in the aqueous solution, we also determine the driving force for nucleation of the hydrate, as a function of temperature, at different pressures. In particular, we use two different thermodynamic routes to evaluate the change in chemical potential for hydrate formation. Although the driving force for nucleation slightly decreases (in absolute value) when the pressure is increased, our results indicate that the effect of pressure can be considered negligible in the range of pressures studied in this work. To the best of our knowledge, this is the first time the driving force for nucleation of a hydrate that exhibits crystallographic structure sII, along its dissociation line, is studied from computer simulation.

An In situ Proton Filter Covalent Organic Framework Catalyst for Highly Efficient Aqueous Electrochemical Ammonia Production

AbstractThe electrocatalytic nitrogen reduction reaction (NRR) driven by renewable electricity provides a green synthesis route for ammonia (NH3) production under ambient conditions but suffers from a low conversion yield and poor Faradaic efficiency (F.E.) because of strong competition from hydrogen evolution reaction (HER) and the poor solubility of N2 in aqueous systems. Herein, an in situ proton filter covalent organic framework catalyst (Ru‐Tta‐Dfp) is reported with inherent Ruthenium (Ru) sites where the framework controls reactant diffusion by suppressing proton supply and enhancing N2 flux, causing highly selective and efficient catalysis. The smart catalyst design results in a remarkable ammonia production yield rate of 2.03 mg h−1 mgcat−1 with an excellent F.E. of ≈52.9%. The findings are further endorsed with the help of molecular dynamics simulations and control COF systems without in situ proton filter feasibility. The results point to a paradigm shift in engineering high‐performance NRR electrocatalysts for more feasible green NH3 production.

Synergistic Spatial Confining Effect and O Vacancy in WO3 Hollow Sphere for Enhanced N2 Reduction.

Visible-light-driven N2 reduction into NH3 in pure H2O provides an energy-saving alternative to the Haber-Bosch process for ammonia synthesizing. However, the thermodynamic stability of N≡N and low water solubility of N2 remain the key bottlenecks. Here, we propose a solution by developing a WO3-x hollow sphere with oxygen vacancies. Experimental analysis reveals that the hollow sphere structure greatly promotes the enrichment of N2 molecules in the inner cavity and facilitates the chemisorption of N2 onto WO3-x-HS. The outer layer's thin shell facilitates the photogenerated charge transfer and the full exposure of O vacancies as active sites. O vacancies exposed on the surface accelerate the activation of N≡N triple bonds. As such, the optimized catalyst shows a NH3 generation rate of 140.08 μmol g-1 h-1, which is 7.94 times higher than the counterpart WO3-bulk.

Prediction of nitrogen solubility in ionic liquids by machine learning methods based on COSMO-derived descriptors

The inertness of nitrogen (N2) results in extremely low N2 solubility in most solvents. However, in some important reactions, such as the nitrogen reduction reaction (NRR) driven by light or electrical energy, sufficient N2 feedstock in electrolyte allows the reaction to proceed more smoothly. In this context, the study concerning N2 solubility is of great significance. Previous research has demonstrated that ionic liquids (ILs) have many special characteristics and can be taken as green solvents to enhance N2 solubility. Herein, two quantitative structure–property relationship (QSPR) models are established to predict the N2 solubility in ILs by combining machine learning methods of random forest (RF) and gradient boosting regressor (GBR) with ionic fragments contribution (IFC) method. Firstly, a database with 385 N2 solubilities in 38 ILs at various temperatures and pressures is collected, in which the ILs are separated into 27 ionic fragments. Then COSMO-derived descriptors for the cations and anions of ILs are calculated and used as input variables. In specific, the determination of coefficient (R2) for the training sets by RF-IFC and GBR-IFC is 0.9983 and 0.9999, respectively. The application examples of N2 solubility in 1-hexyl-3-methyl-imidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][eFAP]) confirm the availability and usefulness of RF-IFC and GBR-IFC models, indicating that both two models are feasible and reliable for predicting N2 solubility in ILs, and hopefully can be used to design and screen ILs in the future.

Exploiting monoterpenoids in type V deep eutectic solvents: A combined high-pressure experiments and theoretical approach for enhanced carbon dioxide and nitrogen absorption

This comprehensive study investigates the development, characterization, and application of natural hydrophobic deep eutectic solvents (HDES) in high-pressure gas capture, focusing specifically on carbon dioxide (CO2) and nitrogen (N2). Two binary HDES systems were formulated, using LnA as a hydrogen bond donor (HBD) and CAR and CIN as hydrogen bond acceptors (HBA). The HDES materials were thoroughly characterized, examining properties such as density, viscosity, conductivity, acidity, surface tension, and hydrophobicity across varying temperature ranges using state-of-the-art equipment. High-pressure gas solubility experiments were conducted to assess CO2 and N2 sorption capacities, demonstrating promising results. Simultaneously, an integrated computational approach was applied: COSMO-RS was used to predict solid–liquid equilibria (SLE) and the eutectic point of the NADES, while Density Functional Theory (DFT) calculations aided in optimizing molecular geometries and understanding the dispersion interactions. Furthermore, molecular dynamics (MD) simulations were employed to evaluate solubility of CO2 and N2 in the NADES and their interaction energies. The results from this dual experimental and computational approach show the potential of these HDES systems in high-pressure gas capture. This study represents a significant addition to the knowledge of deep eutectic solvents, their synthesis, characterization, predictive modeling, and practical applications.

Copolyimide Brushes as a Component of a Hybrid Poly(phenylene Oxide) Membrane for Controlling Gas Separation: Effect of Water, Methanol, and Hexane Vapors.

The effect of water, methanol, and hexane vapors on gas permeability was studied in a hybrid membrane containing 5 wt% copolyimide brushes with poly(methyl methacrylate) side chains (PI-g-PMMA) in a poly(phenylene oxide) (PPO) matrix, and in a pristine PPO membrane. These membranes in the form of dense nonporous films were further examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM), as well as by measuring their mechanical and gas transport properties. A gas separation study of the membranes in a dry state and the membranes saturated with water, methanol, and hexane vapors was performed to estimate the effect of each vapor on the H2, CO2, N2 permeability and selectivity in the separation of H2/N2 and CO2/N2 pairs. In general, saturation with water, methanol, and hexane vapors caused a decrease in the gas permeability of both membranes. The hybrid membrane containing copolyimide brushes demonstrated enhanced selectivity in the separation of H2/N2 and CO2/N2 pairs. It was found that a special effect of the vapors used for membrane saturation is associated with their molar volume. The solubility and diffusion coefficients of N2 and CO2 were obtained by Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations.

Perspective on the interfacial engineering for electrocatalytic N2 to NH3 conversion from catalysts to systems

AbstractAmmonia (NH3) has received significant attention due to its increasing demand as a key commodity for industrial chemical production, a green fuel, and a hydrogen (H2) carrier. Electrochemical nitrogen (N2) reduction reaction (ENRR) emerges as the most attractive pathway to produce NH3. The process utilizes H2O as a proton source under mild temperature and pressure, which can reduce CO2 emissions and energy input compared to the traditional Haber‐Bosch process. However, ENRR is severely insufficient for practical applications due to its kinetically sluggish steps compared to its competitive hydrogen evolution reaction. Also, the imbalanced reactant concentrations of N2 and H2O, resulting from the low N2 solubility, and oppositely, free H2O accessibility toward catalysts, cause the ineffective three‐phase‐boundary that acts as active sites for ENRR. To overcome these challenges, it is essential to perform interfacial engineering for each part of the catalyst and reaction environment. In this perspective, recent advances in interfacial engineering are examined and critically reviewed, and further research directions are proposed to develop ENRR significantly. The sections cover catalytic active site modification, hydrophobic/hydrophilic control, electrolyte engineering, and system design. The insights and prospects in this perspective will be effective for developing ENRR in a scientific and practical manner.

Highly selective NH3 synthesis from N2 on electron-rich Bi0 in a pressurized electrolyzer

Electrochemical conversion of N2 into ammonia presents a sustainable pathway to produce hydrogen storage carrier but yet requires further advancement in electrocatalyst design and electrolyzer integration. This technology suffers from low selectivity and yield owing to the extremely strong N≡N bond and the exceptionally low solubility of N2 in aqueous systems. A high NH3 synthesis performance is restricted by the high activation energy of N≡N bond and the supply insufficiency of N2 to active sites. This paper describes the introduction of electron-rich Bi0 sites into Ag catalysts with a high-pressure electrolyzer that enables a dramatically enhanced Faradaic efficiency of 44.0% and yield of 28.43 μg cm-2 h-1 at 4.0 MPa. Combined with density functional theory results, in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy demonstrates that N2 reduction reaction follows an associative mechanism, in which a high coverage of N-N bond and -NH2 intermediates suggest electron-rich Bi0 boosts sound activation of N2 molecules and low hydrogenation barrier. The proposed strategy of engineering electrochemical catalysts and devices provides powerful guidelines for achieving industrial-level green ammonia production.