Here, we propose the hydrophobic porous ionic liquids (PILs) for CO2 capture and conversion from humid flue gas. Specifically, silver was introduced onto the surface of ZIF-90 and the resultant material was incorporated into the hydrophobic ionic liquids (ILs) to form Type III PILs. The obtained LADDA-PIL exhibited an exceptional CO2 absorption capacity and CO2/N-2 (15/85) selectivity of 2021, surpassing nearly all previously reported porous liquids. Dynamic breakthrough experiments confirmed that LADDA-PIL successfully captured CO2 from humid flue gas. Moreover, the pi-interaction between silver in LADDA-PIL and the alkynyl group enabled high-yield carboxylative cyclization of CO2 with propargylic alcohols at ambient temperature. Density functional theory calculations and molecular dynamics simulations revealed that the hydrophobic ILs act as an effective H2O barrier, while the -NH2 moiety of the ILs facilitates CO2 transport and conversion. This study offers a promising strategy for energy-efficient carbon capture under humid conditions.

For the selective removal of H2S from natural gas, five deep eutectic solvents (DESs) were designed and synthesized by combining functionalized ionic liquids (ILs) bearing dual tertiary amine sites with high-boiling-point solvents. The thermodynamic parameters for the dissolution of H2S and CO2 in [C4-PMDTA]Br-ME were calculated using variable temperature measurements of solubility and the Krichevsky-Kasarnovsky (K-K) equation. These DESs demonstrate superior H2S performance and H2S/CO2 selectivity over other DESs. Nuclear magnetic resonance, quantum chemical calculations, and molecular dynamics simulation reveal that the efficient capture and separation of H2S originate from the synergistic effect between the protonation of tertiary amine sites and hydrogen-bonding interactions. More importantly, the H2S activated by tertiary amine sites can be efficiently converted into high-value-added thiol products under mild reaction conditions, and DESs can be recovered by water washing extraction. These functionalized DESs offer a promising alternative for the capture and conversion of H2S.

The proton transfer strategy was applied to prepare porous liquids (PLs) via one-step mixing at room temperature. Benefiting from the dual effects of the cavities of UiO-66-OH and the reversible addition reaction between carbonyl sites and H2S, the selective capture of H2S over CO2 and CH4 is achieved. Additionally, these PLs can catalyze the reaction of H2S with α,β-unsaturated carboxylic acid esters to generate thiols and thioethers.

Ionic liquids are treated as advanced materials for the efficient capture and directional conversion of H2S. This study developed an innovative multiscale, rate-based model framework that rigorously couples gas-liquid phase equilibrium, interfacial mass transfer, and reaction kinetics to describe multicomponent reactive separation processes. Low-viscosity, task-specific dual-Lewis-base ionic liquid (DIL)-based hybrid solvent systems were introduced, which leveraged the synergy between thermodynamic and kinetic effects to achieve selective separation of H2S and CO2, resulting in a process-based separation selectivity index of 9.2-10.7. Notably, the specific steam consumption during the regeneration stage is only 1.97-2.16 GJ/t H2S, substantially lower than that of conventional aqueous alkanolamine desulfurization processes. Additionally, the DIL enables the rapid and quantitative conversion of alpha, beta-unsaturated carboxylate esters into high-value thiols and thioethers. On this basis, a low-energy, resource-oriented hybrid process integrating absorption, conversion, and separation was proposed. This work provides new insights into H2S capture and conversion for future industrial natural gas purification.

In this study, aprotic and protic carbonyl-functionalized hydrophobic ionic liquids (CHILs) were designed for the selective separation and conversion of H2S. Impressively, [TMACAC][Tf2N] exhibited a remarkable H2S solubility of 2.286 mol/mol and the H2S/CO2 selectivity of 35.7 at 313.2 K and 1.0 bar H2S partial pressure, exceeding all the reported absorbents under experimental conditions. The thermodynamic parameters for the dissolution of H2S, CO2, and CH4 in [TMACAC][Tf2N] were calculated using variable temperature measurements of solubility and the Krichevsky-Kasarnovsky (K-K) equation. The breakthrough curve verifies the possibility of sequential separation of the components in natural gas. Furthermore, CHILs were used as catalysts for the conversion of H2S to thiols or thioethers by alpha, beta-unsaturated carboxylates, and the self-separation of the products and catalysts was realized. Therefore, these CHILs have obvious superior absorption performance and provide a new strategy for desulfurization of natural gas and utilization of separated H2S.

Abstract In this study, aprotic and protic carbonyl‐functionalized hydrophobic ionic liquids (CHILs) were designed for the selective separation and conversion of H 2 S. Impressively, [TMACAC][Tf 2 N] exhibited a remarkable H 2 S solubility of 2.286 mol/mol and the H 2 S/CO 2 selectivity of 35.7 at 313.2 K and 1.0 bar H 2 S partial pressure, exceeding all the reported absorbents under experimental conditions. The thermodynamic parameters for the dissolution of H 2 S, CO 2 , and CH 4 in [TMACAC][Tf 2 N] were calculated using variable temperature measurements of solubility and the Krichevsky–Kasarnovsky (K–K) equation. The breakthrough curve verifies the possibility of sequential separation of the components in natural gas. Furthermore, CHILs were used as catalysts for the conversion of H 2 S to thiols or thioethers by α, β‐unsaturated carboxylates, and the self‐separation of the products and catalysts was realized. Therefore, these CHILs have obvious superior absorption performance and provide a new strategy for desulfurization of natural gas and utilization of separated H 2 S.

The removal of hydrogen sulfide (H2S), a highly toxic and corrosive component from fossil fuel processing and utilization, constitutes a critical environmental challenge in the clean utilization of carbon resources. The use of O2 as a green oxidant for its catalytic oxidation represents a promising and sustainable removal strategy. While most current gas-liquid systems employ chelated iron catalysts and exhibit favorable catalytic activity, they suffer from inherent limitations such as sluggish regeneration of Fe(ii) and the chemical instability of organic ligands-key obstacles hindering their practical deployment. In this work, we report that basic imidazolium acetate ionic liquids (ILs) can efficiently catalyze the oxidation of H2S to elemental sulfur using molecular O2 under mild conditions, without requiring additional catalysts or additives. Detailed study revealed that imidazolium acetate ILs establish an optimal alkaline environment that promotes both the effective capture and activation of H2S, facilitating its selective oxidation. Moreover, the integrated "solvent-catalyst" design simplifies downstream processing, enabling facile catalyst recovery through simple solid-liquid separation and dehydration. The system maintains high performance over five consecutive cycles without noticeable deactivation, underscoring its robust recyclability. We hold the view that this work not only presents a novel strategy for the coupling of H2S capture and resource utilization, but also serves as a valuable reference for the future development of green, low-energy-consumption and resource-recovery gas purification technologies.

The efficient capture and conversion of hydrogen sulfide (H2S) represent a critical challenge in addressing key issues in energy and environmental fields. In this study, we innovatively designed and synthesized a series of carbonyl-functionalized metallic ionic liquids (CMILs), which exhibit dual functionality as both absorbents and catalysts under mild conditions. Experimental results demonstrate that the [Na-15C][LA] system delivers outstanding performance under ambient conditions (30 degrees C, 1.0 bar), achieving an H2S absorption capacity of 1.73 mol mol(-1), an H2S/CO2 selectivity of 101.2, and an exceptionally high H2S/CH4 selectivity of 1122.2. NMR, FT-IR, and DFT calculations confirm that the carbonyl group serves as the active site for efficient H2S capture. Notably, these CMILs function as highly effective catalysts, facilitating the solvent-free conversion of H2S with alpha,beta-unsaturated carboxylates into thiols and thioethers under mild conditions. Moreover, the system enables spontaneous phase separation between the catalyst and products without requiring additional components, achieving quantitative conversion (>99%) while adhering to green chemistry principles. This integrated design provides a novel technical approach for the efficient capture and resource utilization of H2S.

Abstract The efficient and selective elimination of H2S from natural gas holds considerable practical and scientific importance for gas purification. However, the lack of suitable media that enable high H2S/CO2 selectivity has constrained the resource-oriented utilization of both gases. Herein, we present for the first time the synthesis of a series of carbonyl-functionalized deep eutectic solvents (CFDESs). Systematic gas absorption evaluations demonstrate that these CFDESs enable selective and efficient capture of H2S over CO2 and CH4. It is noteworthy that the CFDES derived from 4-methylcyclohexanone (4M-DMAEE) achieves a remarkable H2S uptake of 1.80 mol/mol (7.34 mol/kg) under conditions of 313.2 K and 1.0 bar, marking one of the highest recorded values to date. Leveraging the specific recognition ability of carbonyl groups toward H2S and CO2, 4M-DMAEE shows outstanding H2S/CO2 separation selectivity, particularly under low partial pressure conditions. Moreover, the H2S/CH4 selectivity reaches 519–858 under conditions of 313.2 K and 1.0 bar, outperforming most reported materials. Mechanistic investigations combining NMR, FT-IR, and theoretical calculations reveal a cascade H2S capture process involving nucleophilic addition reactions. Importantly, these CFDESs also feature ultra-low viscosity (<5 mPa·s at 40 °C), favorable mass transfer performance, and excellent cyclic regeneration capability. This work offers a highly selective and energy-efficient separation medium for applications requiring preferential H2S removal and recovery in resource-oriented natural gas upgrading.

The efficient separation of H2S and CO2 is critical for natural gas purification and sulfur resource recovery. In this work, a novel and rigorous rate-based chemical absorption model was developed to describe the selective removal of H2S from natural gas using hydrophobic protic ionic liquids. The model incorporates factors such as gas-liquid interactions, solubility, mass transfer, and reaction kinetics, enabling it to capture the dynamic behavior of the chemical absorption process under non-equilibrium conditions, thereby accurately predicting gas absorption performance and separation efficiency under different operating conditions. The results indicate that the proposed processes exhibit excellent H2S/CO2 separation selectivity and low energy demand. The process-based separation selectivity index increases significantly from 3.5 to 49.2 under low-pressure conditions (0.3 MPa) and from 2.2 to 10.9 under high-pressure conditions (6 MPa). Although the absorbent flow rate and electricity consumption increased, the amount of regeneration steam required for the proposed process was significantly reduced. As a result, the total operating cost was reduced by 39.6 % at 0.3 MPa and by 15.8 % at 6 MPa, compared to the commercial aqueous MDEA desulfurization process.

The efficient and selective capture of SO2 from flue gas remains a critical challenge due to the high viscosity and poor SO2/CO2 selectivity of conventional functionalized ionic liquids (FILs). Herein, a series of carboxylatefunctionalized ionic liquids based on tetraethylammonium ([N2222]) with different anions (DMG, NA, ImAc) were synthesized, and high-boiling sulfolane (SUL), ethylene glycol (EG), and N-methylpyrrolidone (NMP) were introduced as co-solvents to reduce viscosity and tune the interaction environment. Among all systems, the [N2222][ImAc]-SUL mixed solvent exhibited the best comprehensive performance, achieving an ultrahigh SO2 absorption capacity of 15.9 mol/kg at 293.2 K and an outstanding SO2/CO2 selectivity of 36.0. Combined FT-IR and NMR characterizations with DFT calculations and molecular dynamics simulations revealed a multi-site synergistic mechanism: the carboxylate oxygen (-COO-) serves as the primary chemisorption site (Delta H =-67.9 kJ/mol), the sp2-hybridized imidazole nitrogen provides auxiliary coordination, and sulfolane contributes physical solvation via dipole-dipole interactions. Furthermore, the system demonstrated satisfactory cyclic stability over five absorption-desorption cycles at a mild regeneration temperature of 343.2 K. This work provides a highly promising absorbent for industrial SO2 emission control and offers mechanistic insights for designing selective acid gas capture systems.

Desulfurization and decarbonization are indispensable processes in natural gas upgrading. Although functionalized ionic liquids (ILs) have demonstrated potential in gas purification, their practical application is hindered by insufficient absorption capacities for H2S and CO2 under low partial pressure condition. To address this limitation, a series of novel protic thiolate ILs (TILs) through acid-base neutralization reactions between organic superbases and thiols have been developed in this work. The capture performance of H2S, CO2, and CH4 by these TILs was systematically investigated at temperatures ranging from 303.2 to 343.2 K. Notably, the representative TIL formed by 1,5-diazabicyclo [4.3.0] non-5-ene and 3-mercapto-1-propanol ([DBNH][MP]) demonstrated remarkable absorption capacities, achieving 1.42 mol/mol (6.58 mol/kg) for H2S and 0.95 mol/mol (4.37 mol/ kg) for CO2 at 303.2 K and 1.0 bar. Even under reduced pressure condition (0.05 bar), [DBNH][MP] maintained exceptional absorption performance, with capacities of 1.00 mol/mol for H2S and 0.81 mol/mol for CO2. Moreover, the H2S/CH4 and CO2/CH4 selectivities in [DBNH][MP] also reached 838 and 680 (0.05 bar H2S/CO2 vs. 1.0 bar CH4), respectively, surpassing those of all previously reported absorbents. To elucidate the underlying mechanisms, we conducted comprehensive characterization studies using nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. Density functional theory (DFT) calculations coupled with independent gradient model based on Hirshfeld partition (IGMH) analysis revealed that the exceptional gases capture performance originates from strong chemical interactions between thiolate anions (RS-) and the target gas molecules. These findings demonstrate that the developed TILs are promising candidates for the simultaneous removal of H2S and CO2 during natural gas upgrading processes.

Natural deep eutectic solvents (NDESs) are recognized as promising membrane materials for sustainable SO2 separation. Evaluating their separation performances is necessary, as well as understanding of the role that each hydrogen bonding site (including anion and functional groups in NDESs) plays in SO2 separation. Herein, three choline chloride (ChCl)-based NDESs bearing different number and type of functional groups were firstly incorporated into Pebax matrix to fabricate blended membranes for removing SO2 from CO2 and N-2. The Pebax/NDES membranes show SO2 permeability up to 10502 Barrer (0.20 bar and 40 degrees C), with excellent SO2/N-2 and SO2/CO2 selectivity of 1808 and 62.5 obtained, respectively, which are enhanced by 156 %, 61.5 % and 56.1 % compared with those in neat Pebax membrane. By means of gas solubility and diffusivity measurements, quantum chemical calculations and spectral characterizations, the highly-reversible multi-site interactions between SO2 and hydrogen bonding sites in NDESs (Cl- center dot center dot center dot SO2, carbonyl O center dot center dot center dot SO2 and hydroxyl O center dot center dot center dot SO2) were revealed. Meanwhile, the strength of hydrogen bonding network inside the NDESs, which is governed by the hydrogen bonding sites, is found to significantly influence the gas diffusion. More importantly, SO2/CO2/N-2 (2.5/15/82.5 mol%) mixed gas separation experiment also displays the superior separation performance and long-term stability of Pebax/NDES membrane.

This study presents a comprehensive overview of a pioneering 1 million-ton carbon capture, utilization, and storage (CCUS) project implemented in the Qilu Petrochemical Shengli Oilfield in China. The project involved a compression-condensation-purification process and aimed to capture CO2 from the coal gas of the second chemical fertiliser plant of the Qilu Petrochemical Company. Molecular sieves were used to dry the captured CO2, and MellapakPlus™ structured packing was employed for purification. Two novel energy-saving processes were implemented, a lithium bromide refrigerator unit to recover waste heat for cooling and an expansion generator unit to recover pressure energy from the tail gas. The project layout and land area were carefully determined. The consumption of utilities in the capture system was analysed. Furthermore, an economic assessment of the project was conducted. The technical and economic feasibility of this project was confirmed by the findings. The comprehensive energy consumption per unit of the capture process was 2.649 GJ/t CO2, the total investment (excluding tax) for CO2 capture was CNY 380 million (380 CNY/t CO2), the payback period of the project was 9.20 years, and the sales price (excluding tax) of the project was 194.4 CNY/t CO2 at a yield of 8%.

Separation of C 2 H 2 from industrially important gas pairs using energy‐efficient adsorptive techniques with multifunctional porous materials remains a significant yet challenging issue. Here, we report the highly efficient separation of C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures with isostructural metal‐containing hydrogen‐bonded organic frameworks (M–HOFs), which feature micropore channels decorated with high‐density and uncoordinated carboxyl groups. Single‐crystal X‐ray diffraction analysis reveals that each free carboxyl group is capable of trapping one C 2 H 2 molecule through hydrogen bonding. This endows the M–HOFs with excellent C 2 H 2 capture capability, achieving a benchmark storage density of 396.0 mg cm −3 , while simultaneously demonstrating remarkable selectivity over C 2 H 4 (420–97) and CO 2 (188–53). Breakthrough experiments confirm that binary gas mixtures can be efficiently separated by M–HOFs, where an impressive C 2 H 4 productivity (137.4 mol kg −1 ) is realized in the separation of C 2 H 2 /C 2 H 4 (1/99), and an outstanding separation factor (17) is achieved for C 2 H 2 /CO 2 (50/50) splitting. Coupled with their superior chemical stability, these M–HOFs display tremendous potential for practical applications.

This study introduces innovative hydrophobic nanostructured composite deep eutectic solvents (HS-SiO2/DBUEG) to overcome limitations of amine absorbents in humid CO2. The HS-SiO2/DBU-EG achieved a significantly enhanced CO2 absorption capacity of 4.14 mol/kg and maintaining a high regeneration efficiency of 95 %, attributed to its inherent synergistically hydrophobic nanostructure. In contrast, while DBU-EG showed improved absorption under humid CO2 but reduced regeneration performance. Spectroscopic analysis revealed that DBU-EG relies on hydrolysis-induced N-sites for absorption, but the resulting products are challenging to decompose. Conversely, HS-SiO2/DBU-EG utilizes the O-sites of EG as the absorption sites, a mechanism supported by thermodynamic analysis and quantum calculations demonstrating a low enthalpy change value of the reaction. Fixed-bed experiments further confirmed its efficient and continuous absorption performance. This research emphasizes the value of low-energy absorption mechanisms and hydrophobic design for advanced industrial CO2 capture.

Removing H2S and CO2 is of great significance for natural gas purification. With excellent gas affinity and tunable structure, ionic liquids (ILs) have been regarded as nontrivial candidates for fabricating polymer-based membranes. Herein, we firstly reported the incorporation of protic ILs (PILs) having ether-rich and carboxylate sites (ECPILs) into poly(ether-block-amide) (Pebax) matrix for efficient separation H2S and CO2 from CH4. Notably, the optimal permeability of H2S reaches up to 4310 Barrer (40 ºC, 0.50 bar) in Pebax/ECPIL membranes, along with H2S/CH4 and (H2S+CO2)/CH4 selectivity of 97.7 and 112.3, respectively. These values are increased by 1125%, 160.8% and 145.9% compared to those in neat Pebax membrane. Additionally, the solubility and diffusion coefficients of the gases were measured, demonstrating that ECPIL can simultaneously strengthen the dissolution and diffusion of H2S and CO2, thus elevating the permeability and permselectivity. By using quantum chemical calculations and FT-IR spectroscopy, the highly reversible multi-site hydrogen bonding interaction between ECPILs and H2S was revealed, which is responsible for the fast permeation of H2S and good selectivity. Furthermore, H2S/CO2/CH4 (3/3/94 mol%) ternary mixed gas can be efficiently and stably separated by Pebax/ECPIL membrane for at least 100 h. Overall, this work not only illustrates that PILs with ether-rich and carboxylate hydrogen bonding sites are outstanding materials for simultaneous removal of H2S and CO2, but may also provide a novel insight into the design of membrane materials for natural gas upgrading.

Separation of C 2 H 2 from industrially important gas pairs using energy-efficient adsorptive techniques with multifunctional porous materials remains a significant yet challenging issue. Here, we report the highly efficient separation of C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures with isostructural metal-containing hydrogen-bonded organic frameworks (M–HOFs), which feature micropore channels decorated with high-density and uncoordinated carboxyl groups. Single-crystal X-ray diffraction analysis reveals that each free carboxyl group is capable of trapping one C 2 H 2 molecule through hydrogen bonding. This endows the M–HOFs with excellent C 2 H 2 capture capability, achieving a benchmark storage density of 396.0 mg cm −3 , while simultaneously demonstrating remarkable selectivity over C 2 H 4 (420–97) and CO 2 (188–53). Breakthrough experiments confirm that binary gas mixtures can be efficiently separated by M–HOFs, where an impressive C 2 H 4 productivity (137.4 mol kg −1 ) is realized in the separation of C 2 H 2 /C 2 H 4 (1/99), and an outstanding separation factor (17) is achieved for C 2 H 2 /CO 2 (50/50) splitting. Coupled with their superior chemical stability, these M–HOFs display tremendous potential for practical applications.