Cyano-containing ionic liquids for the extraction of aromatic hydrocarbons from an aromatic/aliphatic mixture

Ionic liquids can replace conventional solvents in aromatic/aliphatic extractions, if they have higher aromatic distribution coefficients and higher or similar aromatic/aliphatic selectivities. Also physical properties, such as density and viscosity, must be taken into account if a solvent is applied in an industrial extraction process. Cyano-containing ionic liquids have a lower density than the benchmark solvent sulfolane and a higher viscosity. Sulfolane is from a hydrodynamic point of view a better solvent than ionic liquids for the aromatic/aliphatic extraction. The most suitable ionic liquids for the extraction of aromatic hydrocarbons from a mixture of aromatic and aliphatic hydrocarbons are [bmim]C(CN)(3), [3-mebupy]N(CN)(2), [3-mebupy]C(CN)(3), [3-mebupy]B(CN)(4) and [mebupyrr]B(CN)(4). They have factors of 1.2-2.3 higher mass-based distribution coefficients than sulfolane and a similar or higher, up to a factor of 1.9 higher, aromatic/aliphatic selectivity than sulfolane. The IL [3-mebupy]N(CN)(2) is a better extractant for the separation of toluene from a mixture of toluene/n-heptane in a pilot plant Rotating Disc Contactor (RDC) than sulfolan

Vielversprechende Loesungsmittel. Ionisch Fluessigkeiten als alternative Loesungsmittel bei der Extraction von petrochemikalien

Die Trennung aromatischer von aliphatischen Kohlenwasserstoffverbindungen stellt insofern eine Herausforderung dar, als diese Kohlenwasserstoffe nah beieinander liegende Siedepunkte aufweisen und verschiedene Kombinationen azeotroper Gemische bilden [1]. Die herkömmlichen Verfahren zur Trennung dieser aromatischen und aliphatischen Kohlenwasserstoffverbindungen sind die Flüssigextraktion, die für den Bereich von 20–65 Gew.-% aromatischer Inhaltsstoffe geeignet ist, die Extraktivdestillation für den Bereich von 65–90 Gew.-% an Aromaten und die azeotrope Destillation für einen hohen Gehalt an Aromaten, >90 Gew.-%. Typische Lösungsmittel, die verwendet werden, sind polare Komponenten wie z. B. Sulfolan, N-Methylpyrrolidon (NMP), N-Formylmorpholin (NFM), Ethylenglycole oder Propylenkarbonat

Ternary liquid-liquid equilibria for mixtures of an aromatic + an aliphatic hydrocarbon + 4-methyl-N-butylpyridinium tetrafluoroborate

This research focused on a study of the ionic liquid 4-methyl-N-butylpyridinium tetrafluoroborate ([mebupy]BF4) as a solvent in liquid-liquid extraction. Liquid-liquid equilibrium data were obtained for mixtures of 4-methyl-N-butylpyridinium tetrafluoroborate + (benzene or ethylbenzene or m-xylene) + (N-hexane or N-octane) at T = (313.2 and 348.2) K and T = (313.2 and 333.2) K for the ternary mixture with benzene and p = 0.1 MPa. The experimental data for the binary and ternary systems were well-correlated with the NRTL model. The aromatic/aliphatic selectivity values were comparable to those of toluene + N-heptane. The ionic liquid [mebupy]BF4 is therefore a suitable solvent for an industrial extraction process for the separation of aromatic and aliphatic hydrocarbons

Renewable glycoaldehyde isolation from pyrolysis oil by reactive extraction with primary amines

The transition to a sustainable bio-based economy has rapidly increased the interest to obtain renewable platform chemicals from biomass. Glycolaldehyde is one of potential future platform chemicals, which is present in high quantity (5–13 wt%) in wood-derived pyrolysis oil. Water addition to pyrolysis oil isolates glycolaldehyde and other polar compounds, nearly quantitatively in the aqueous phase. In order to apply extraction for the subsequent glycolaldehyde recovery a water-insoluble solvent is required. This work was done to identify a suitable solvent. Firstly, several long chain alkanes and alcohols were evaluated by extracting an aqueous solution of 6.2 wt% glycolaldehyde. The results demonstrated that alkanes cannot extract glycolaldehyde whereas the distribution coefficient of glycolaldehyde in alcohols decreases with chain length, from 0.23 for 1-octanol to 0.04 for oleyl alcohol. Due to low distribution coefficients, primary amines were considered extractants since they can form reversible imines with aldehydes. A solution of 1 M Primene JM-T in 1-octanol and pure Primene JM-T increases the distribution coefficient of glycolaldehyde in 1-octanol by a factor of 10 and 75, respectively. The extraction factors are 0.46 for 1-octanol, 3.79 for 1 M Primene JM-T in 1-octanol and 30.87 for pure Primene JM-T. Another alternative is aniline derivatives. At a concentration of 1 M, 4-ethylaniline gives more than two orders of magnitude higher distribution ratio than 2-ethylaniline and Primene JM-T. The extraction capability of amines is: octylamine >4-ethylaniline >phenylethylamine >>Primene JM-T >2-ethylaniline. In conclusion, highly branched primary amines and orthoalkylanilines are promising extractants, taking into account the reversibility of the Schiff base formation. The final selection of the most suitable extractant/diluent combination will depend on the actual selectivity towards glycolaldehyde and back-extraction yield

Production of discrete oxygenated target chemicals from pyrolysis oil

Biomass is a promising renewable feedstock for chemicals. Pyrolysis of biomass produces a dark, brown coloured liquid (bio oil), which consists of a complex mixture of oxygenated hydrocarbons, water and char. The key advantage of the produced bio-liquids over crude oil is their high content of oxygenates

Laboratory scale conceptual process development for the isolation of renewable glycolaldehyde from pyrolysis oil to produce fermentation feedstock

A laboratory-based separation sequence has been developed to produce an aqueous glycolaldehyde solution as fermentation feedstock. It consists of water extraction of pyrolysis oil, acid removal, water removal, octanol extraction, phenolic removal, back-extraction, and washing. The octanol-free aqueous glycolaldehyde solution contains approximately 4 wt% glycolaldehyde, which meets the requirement of fermentation feedstoc

Pilot plant study on the extractive distillation of toluene-methylcyclohexane mixtures using NMP and the ionic liquid [hmim][TCB] as solvents

\u3cp\u3eThe separation of the close-boiling point mixture: toluene - methylcyclohexane can be carried out by extractive distillation using the ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate ([hmim][TCB]), reported as promising solvent for the separation of this mixture. However, the polar nature of ionic liquids causes the formation of two liquid phases which can be overcome with high solvent-to-feed ratios (S/F) resulting in high liquid phase viscosities that cause mass transfer limitations. Experiments in an extractive distillation pilot plant were performed with the objective of firstly exploring different operating conditions and secondly to compare the mass transfer efficiencies produced by [hmim][TCB] and the reference organic solvent N-methyl-2-pyrrolidone. Pure viscosity, density and surface tension data as well as ternary viscosity and density data of tolune - methylcyclohexane - [hmim][TCB] were measured to compute the mass transfer efficiency. From pilot plant experiments it was found that all the studied operating conditions did not form two-liquid phases. However, the high solvent-to-feed ratios increased the liquid phase viscosities and consequently the use of this ionic liquid produces Height Equivalent to a Theoretical Plates (HETPs) twice as high as the reference solvent NMP causing slightly lower top purities and a longer required distillation column for a required separation.\u3c/p\u3

Solvent properties of functionalized ionic liquids for CO2 absorption

onic liqs. can be used as solvents for gas absorption operations in order to improve the process economy and general efficiency of gas sepns. This work investigates solvent properties of ionic liqs. and compares them to amine solns. used for absorption of carbon dioxide (CO2). The CO2 soly. into six different room temp. ionic liqs. (RTILs) was measured at temps. between 298-343 K and pressures up to about 1 MPa. The RTILs used were: [bmim]+[BF4]-, [bmim]+[DCA]-, and four imidazolium-based ionic liqs. paired with [DCA] and [BF4], in which the cation was functionalized with either a primary, tertiary amine or a hydroxyl group. The d., viscosity and surface tension of the studied RTILs were measured at temps. ranging from 293-363 K. The results showed that CO2 absorption behavior was affected by the functionalized chains appended to the RTILs cation. A chem. enhancement of the CO2 absorption was obsd. when functionalized RTILs were used as absorption solvents. It was possible to increase the ionic liq. volumetric gas load almost threefold by attaching functional groups to the ionic liq., whereas for the traditional amine solns. the max. gas load is stoichiometrically limited

Binary and ternary (liquid + liquid) equilibrium for {methylcyclohexane (1) + toluene (2) + 1-hexyl-3-methylimidazolium tetracyanoborate (3)/1-butyl-3-methylimidazolium tetracyanoborate (3))

This paper focuses on the study of the solubility behaviour of 1-hexyl-3-methylimidazolium tetracyanoborate [HMIM][TCB] and 1-butyl-3-methylimidazolium tetracyanoborate [BMIM][TCB] in combination with methylcyclohexane and toluene as representatives for non-aromatic and aromatic components. Binary and ternary (liquid + liquid) equilibrium data were collected at three different temperatures and at atmospheric pressure (0.1 MPa). The experimental data were well-correlated with the NRTL and UNIQUAC thermodynamic models; however, the UNIQUAC model gave better predictions than the NRTL, with a root mean square error below 0.97%. The non-aromatic/aromatic selectivities of the ionic liquids make them suitable solvents to be used in extractive distillation processe