Search

Ionic liquids (ILs) are promising solvents for separating aromatics from fuel oils. However, studies for separate polycyclic aromatics with ILs are rare and insufficient, and the impact of solute structure on extraction performance still needs to be determined. In this work, we use 1‐ethyl‐3‐methylimidazolium bis([trifluoromethyl]sulfonyl)imide ([EMIM][NTF2]) as an extractant to separate 1‐methylnaphthalene, quinoline, and benzothiophene from dodecane mixtures. Liquid–liquid equilibrium experiments identified the optimal operating conditions. Nine solute molecules, including five alkanes and four aromatic hydrocarbons, were used to study the relationship between extraction performance and solute structure. Molecular dynamics simulation and quantum chemistry calculations gave a deep insight and reasonable interpretation of the structure‐performance relationship at the molecular level. An industrial‐scale extraction process was proposed. The IL can be easily regenerated using heptane as a back‐extractive solvent. A high‐purity fuel oil with aromatic content below 0.5 wt% is obtained after 8‐stage extraction. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) as promising green drying agents were first proposed to natural gas (NG) dehydration. In this work, choline chloride (ChCl)‐based DESs were prepared using ChCl as hydrogen bond acceptor (HBA) and triethylene glycol (TEG), ethylene glycol (EG) or Urea as hydrogen bond donors (HBDs). To explore the potential application, methane (CH4) dehydration experiment was conducted to verify the dehydration performance using prepared DESs. The thermodynamic properties were predicted by COSMO‐RS model (Conductor‐like screening model for real solvents). The quantum chemistry calculation was applied to understand the separation mechanism at the molecular level. The absorption performance of H2O in DESs depends on the weak interaction between Cl atom (or N and O atom) of ChCl and H atom of H2O as well as the free volume of DESs. Molecular dynamics (MD) simulation discloses the intermolecular interaction between HBA and HBD. This work makes the first multi‐scale analysis on NG dehydration using DESs. [ABSTRACT FROM AUTHOR]

• A control test was carried out based on the prediction results of COSMO-RS model. • Extraction efficiency of TP and BTP by TEAC:PrA were 98.06 % and 98.53 %, respectively. • The structure–activity relationship between DES and TP or BTP was studied by molecular simulation. • The interaction types and site distribution of extractive desulphurization were revealed at the atomic level. The improvement of fuel quality requires the reduction of sulfur content. The main challenge of catalytic cracking diesel extraction desulfurization is to find low-price and good-performance extractants. Based on experimental research, this work further explores the separation mechanism of DES for thiophene (TP) and benzothiophene (BTP). First, the COSMOS-RS model was used to predict the separation performance of 10 HBAs and 10 HBDs for TP and BTP. The results showed that the low-cost carboxylic acid based DES had excellent separation performance. Secondly, the effect of experimental conditions on the separation performance of three carboxylic acid based DESs was investigated. When the molar ratio of DES to TP and BTP was 3:1, after three stage extraction, the extraction rates of TP and BTP by TEAC: PrA(1:3) were 98.06 % and 98.53 %, respectively. Finally, the structure–activity relationship was studied by using quantum chemistry and molecular dynamics simulation. It was found that E vdW plays a dominant role in the desulfurization process and does not include H-bond interactions. TEA+ was distributed parallel to the aromatic ring and has a CH···π interaction with thiophene. TP and BTP were distributed in the voids of DES and do not affect the regeneration performance of DES. [ABSTRACT FROM AUTHOR]

The effective separation of ethyl acetate (EAC)/isopropanol(IPA)/water azeotrope from industrial wastewater significantly reduces environmental risks and recycling resources. An azeotrope separation technique was proposed, combining ionic liquid mixed entrainer and dividing wall column extractive distillation (DWC-ED). The selectivity and solubility of 225 ionic liquids were calculated based on the COSMO-RS model. The molecular polarity of EAC, IPA, H 2 O, dimethyl sulfoxide (DMSO), and [EMIM][AC] was studied, and 1-ethyl-3-methylimidazolium acetate ([EMIM][AC]) was determined as the best solvent. In addition, the interaction mechanism between [EMIM][AC] (or DMSO) and EAC/IPA/H 2 O was studied using the quantum chemistry (QC) theory. Independent gradient model (IGM), interaction energy, and atoms in molecules (AIM) analysis showed that hydrogen bonds and vdW forces were formed between [AC]− anion and H 2 O/IPA/EAC, and the interaction energy was gradually weakened, which significantly improved the performance of extractive distillation process. The results showed that the total annual cost (TAC) and energy consumption of IL-based mixed solvent extractive distillation were reduced by 36.04 % and 37.72 %, respectively, compared to the single DMSO extractive distillation process. The TAC and energy consumption of the DWC-ED process were 44.61 % and 51.43 % lower than the benchmark processes. [ABSTRACT FROM AUTHOR]

A clean and sustainable process for separating n-heptanol/n-hexanol/water industrial mixing system by extractive distillation via mixing organic solvent with ionic liquid as an entrainer was proposed. The mechanism of intermolecular microscopic interaction was explored by quantum chemistry calculation. By using multi-objective optimization, the optimal operating parameters of the process were obtained. In addition, process intensification technology was introduced, which improved the problems of high cost and high energy consumption in the conventional extractive distillation process. Finally, multiple performances were evaluated and analyzed for different processes. It was found that the coupled heat integration and heat pump technology to assist the extractive distillation process saved 10.45% in terms of economy, reduced gas emissions by 49.00%, and reduced energy consumption by 48.99% compared to the basic extractive distillation process. This confirmed the reliability and feasibility of implementing the process intensification technology. This work demonstrates the application of organic solvent mixed with ionic liquid as entrainer and process intensification technology in the extractive distillation process, providing guidance and reference for the design of the extractive distillation process. [ABSTRACT FROM AUTHOR]

• The application of DESs in MTBE production is proposed for the first. • An extraction coupled distillation process based on DESs was developed. • The separation mechanism of DESs was elucidated at molecular scale. • DESs was determined by quantum chemistry and molecular dynamics simulation. Deep eutectic solvents (DESs) were first applied in the azeotrope separation process for the production of methyl tert -butyl ether (MTBE). Quantum chemistry and molecular dynamics simulations were used to explore the interaction mechanism of ChCl-based DESs in the liquid–liquid extraction of the MTBE–methanol (MeOH) system. The results showed that the extraction of MeOH by DESs mainly depended on the Van der Waals interactions between Cl atoms in ChCl and H atoms in the MeOH hydroxyl group. Hydrogen bond donors also enhanced the extraction effect to a certain extent. Liquid-liquid equilibrium experiments were carried out for the three selected DESs, and the ideal separation effect was obtained. The complete separation process of the MTBE-MeOH system was developed based on experimental data. This work demonstrates the application of DESs in the MTBE-MEOH system and provides guidance for the selecting and analysis of other DES extractants for the separation of low-carbon alcohol systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • The IL ([EMIM][DEP]) can efficiently capture the higher alcohols from CO 2 gas mixture; • Interaction mechanisms were identified at the molecular level; • The relationship between VLE behaviors and HB interactions was explored; • Capturing higher alcohols from CO 2 gas with ILs is a process intensification technology. Ionic liquids (ILs) as green solvents were first proposed to capture low-carbon alcohols (e.g., methanol, ethanol and 1-propanol) from the syngas tail gas. The vapor–liquid equilibrium (VLE) data for the binary mixtures of low-carbon alcohols with 1-ethyl-3-methyl-imidazolium diethyl phosphate ([EMIM][DEP]) were experimentally measured. The UNIFAC-Lei model demonstrated the best performance in predicting VLE data among all the investigated predictive molecular thermodynamic models. However, the COSMO-SAC-UNIFAC model could reproduce the low-carbon alcohols gas absorption characteristics without any experimental data input, and was more accurate than the original UNIFAC and COSMO-SAC models in this case. Using quantum chemistry calculations and wave function analysis, the separation mechanism was revealed on a molecular level. The relationship between thermodynamic behaviors and hydrogen bond interactions in CO 2 –low-carbon alcohols–[EMIM][DEP] systems was systematically explored. Additionally, theoretical guidance for the design and screening of task-specific ILs in condensable gas separation processes was provided. [ABSTRACT FROM AUTHOR]