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Deep eutectic solvents (DES) are eutectic mixtures of hydrogen bond acceptors and hydrogen bond donors. The stability of DES depends on the nature of interatomic interactions during their structural formation. This study focuses on the structural analysis of choline chloride (ChCl)-urea DES system (molar ratio 1:2) at the atomic level using density functional theory. Both gauche- and trans- conformers of choline were considered for geometric optimization with chloride anion at various orientations. The most stable structure of each conformer was further considered with urea to optimize the DES structure. Energy Decomposition Analysis (EDA) study showed that the binding energy (Δ E b i n d) for gauche- DES was more negative (−82.59 kJ/mol) than trans- DES (−7.60 kJ/mol). This indicated lower bond strength in trans- DES, hence higher stability in gauche- DES. It also agrees with calculation by dispersion energy, the Bader's atoms-in-molecules theory for electrostatic interactions, the frontier molecular orbital analysis and Non-Covalent Interactions (NCI) analysis. [Display omitted] • The hydrogen bond and dihydrogen bond play major role in the formation of DES. • HOMO-LUMO energy gap confirmed that gauche- DES is less reactive than trans- DES. • Electrostatic interactions are higher for the gauche- DES as per QTAIM theory. • The stability of the gauche- DES structure was mainly affected by the steric energy. [ABSTRACT FROM AUTHOR]

Biobutanol obtained via an acetone–butanol–ethanol(ABE) fermentation process is now considered a potential biofuel.In recent times low density phosphonium cations were found to removebutanol from aqueous solutions. In this regard, low density phosphonium-basedionic liquids (ILs) trihexyl(tetradecyl)phosphonium dicyanamide [TDTHP][DCA]and trihexyl(tetradecyl)phosphonium decanoate [TDTHP][DEC] have beenused for the separation of 1-butanol from aqueous solution. Ternaryliquid–liquid equilibrium data for IL(1)–1-butanol(2)–water(3)are measured at T= 298.15 K and p= 1 atm. Butanol partition coefficients are obtained in the rangeof 25–85 and 20–290 for [TDTHP][DCA] and [TDTHP][DEC],respectively. 1H NMR spectra indicates the absence of ILand water in the raffinate and extract phase, respectively. This experimentallyconfirms that there will be negligible cross-contamination of waterand IL in either phase. The separation factor of butanol over waterapproaches infinity for both systems. A wider spread of binodal curveindicated a higher recovery of butanol at different feed concentrations.The experimental data were compared with excess Gibb’s freeenergy models, namely the nonrandom two liquid (NRTL) and the universalquasichemical (UNIQUAC) models. NRTL and UNIQUAC gave root mean squaredeviation (RMSD) values in the range of 0.12–0.14% and 0.48–0.55%,respectively, for both ILs. Further the predictive ability of a statisticalmechanical framework was also performed using the well-known COSMO-RSmodel. The COSMO-RS model gave RMSD values of 18.67% and 16.21% forthe systems containing the ILs respectively, [TDTHP][DCA] and [TDTHP][DEC]. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are eco-friendlysolvents due to their lowvapor pressure. Properties such as density should be known as it affectsthe mass transfer rates. Due to its limitless combinations, it isimpractical to measure densities experimentally. For the first time,the cohesion factor in the cubic equations of state (CEOS) is usedto predict the densities of six commercial ILs, namely, 1-ethyl-3-methylimidazoliummethane sulfonate [EMIM][MeSO3], 1-ethyl-3-methylimidazoliumacetate [EMIM][Ac], 1-ethyl-3-methylimidazolium thiocynate [EMIM][SCN],1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO4],Tris(2-hydroxyethyl)-methylammonium methyl sulfate [TEMA][MeSO4], and trihexyl(tetradecyl) phosphonium bis(2,4,4-trimethylpentyl)phosphinate [TDTHP] [Phosph]. CEOS models such as predictive Soave–Redlich–Kwong(PSRK) coupled with cohesion factor gave better results when comparedto the correlations such as Reid et al. (RR), Mchaweh et al. (MH),and the linear generalized model (LGM). In this work the PSRK equationof state (EOS) with the derived NSM1 alpha function and PSRK withoriginal SRK alpha function were used for the prediction. PSRK EOSmodel with NSM1 alpha function and PSRK EOS with original SRK alphafunction proved very accurate with average minimum deviation of 0.02% to 0.44 % and 0.29 % to 0.66 % from experimental values for sixILs, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] LLE of ammonium and phosphonium ionic liquids-aromatic-aliphatic component reported. [•] Experimental data were correlated with NRTL and UNIQUAC models. [•] Successful prediction using quantum chemical based COSMO-RS model. [•] Low cross contamination between both phases reported. [Copyright &y& Elsevier]

Highlights: [•] Low density IL was used for recovery of butanol and propanol from aqueous solution. [•] Raffinate phase contains mainly water due to less solubility of IL in water. [•] Selectivity for extraction of 1-butanol ranges from 50 to 250. [•] Tie line data correlated with NRTL and UNIQUAC model with RMSD <1%. [Copyright &y& Elsevier]

The interaction of CO 2 with different deep eutectic solvents (DES) has been studied at the molecular level using density functional theory. Choline chloride and choline bromide were selected as the hydrogen bond acceptors (HBA); urea, ethylene glycol and glycerol were selected as the hydrogen bond donors (HBD). The type and intensity of interactions in DES and that between DES and CO 2 molecules at various interaction sites as well as the quantification of short-range interactions has been studied using Bader's quantum theory of atoms in molecules (QTAIM). The distribution of electrostatic potential (ESP) charges during these interactions has been detailed using the Charges from ESP using a grid (CHELPG) scheme. The non-covalent interactions have been identified using the reduced density gradient (RDG) analysis. Strong van der Waals forces were observed to contribute in the formation of DES. The highest interaction energy of −10.65 kcal/mol was found between the DES2 that comprised of choline chloride and ethylene glycol in the molar ratio of 1:2 and the CO 2. The results of this study show that both HBA and HBD affect the interaction between CO 2 and DES. This study can contribute in designing more specific DES for CO 2 capture and utilization. [Display omitted] [ABSTRACT FROM AUTHOR]

The thermodynamic analysis of Ca-looping sorption enhanced steam reforming of renewable energy source bio-butanol was carried out. The effect of reformer temperature, steam to carbon molar ratio and CaO to carbon molar ratio were investigated on the production rate of H2, CO, CO2 and CH4. The favorable reformer conditions were proposed as 600°C reformer temperature, steam to carbon molar ratio = 4 and CaO to carbon molar ratio = 1 with respect to hydrogen production rate and utility requirement of Ca-looping process. A process was developed for the application of reformer exhaust gases for solid oxide fuel cell. Performance of different reforming processes (sorption enhanced steam reforming, steam reforming and auto-thermal reforming) was evaluated in terms of overall energy efficiency. Among all these processes the auto-thermal reforming exhibited the highest overall energy efficiency of 77.30% followed by steam reforming (66.57%) and sorption enhanced steam reforming (66.04%). [ABSTRACT FROM AUTHOR]