Screening of Ionic Liquid/H₂O Working Pairs for Application in Low Temperature Driven Sorption Heat Pump Systems

Due to the known corrosion and crystallization issues of LiBr/H₂O, the state-of-the-art working pair in sorption heat pump (SHP) systems, research into alternative working pairs is of high practical relevance. We have studied a wide range of ionic liquids (ILs) for this application in order to find potential new systems with enhanced performance. The screening was conducted with a focus on vapor pressure measurements of, in total, 74 examined working pairs. As common vapor–liquid-equilibrium measurements are very precise but rather time-consuming, we developed a new setup allowing a fast relative determination of humidities with very small sample volumes for screening purposes. By this method we identified seventeen IL/H₂O working pairs fulfilling the technical relevant criterion of a water vapor pressure <i>p</i>_H₂O ≤ 10 mbar at <i>T</i> = 308 K with an IL content of less than 80 wt % (<i>w</i>_IL < 0.8). Further evaluation of these candidates with respect to their thermal stability and viscosity allowed us to identify [MMIM]­[HCOO]/H₂O, [MMIM]­[OAc]/H₂O, [MMIM]­[C₂H₅COO]/H₂O, [Me₄N]­[HCOO]/H₂O, [Me₄N]­[OAc]/H₂O and [Me₄N] [C₂H₅COO]/H₂O as the most promising IL/H₂O systems for a possible application in SHP systems

Continuous Gas-Phase Synthesis of Oxymethylene Dimethyl Ethers Using Supported Ionic Liquid Phase Catalysts

Acidic supported ionic liquid phase catalysts were investigated for the synthesis of oxymethylene dimethyl ethers (OMEs). The application of OME1 and trioxane for the gas-phase synthesis of higher OMEs and in particular the generation of OMEn with n higher than 3 was successfully demonstrated. Raising the pressure led to an increase in the conversion of OME1 and to higher selectivity for higher molecular weight OMEs. Furthermore, a correlation between the ionic liquid’s acidity and the catalytic activity was shown with higher acidity leading to higher conversion of trioxane and OME1. Moreover, successful long-term operation for more than 200 h time on stream has been demonstrated with good catalyst system stability

Solid-State Structures of Double-Long-Chain Imidazolium Ionic Liquids: Influence of Anion Shape on Cation Geometry and Crystal Packing

The syntheses and solid-state structures of a series of imidazolium (IM) salt-based, double C12 alkyl chain functionalized ionic liquids, namely, [C12C12IM][A], where the anion A is I−, I3−, I5−, N(CN)2−, C(CN)3−, B(CN)4−, or SbF6−, are reported. All compounds were fully characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction studies on single crystals. The molecular structure of the IM [C12C12IM]+ cation, as found in the individual crystal packing arrangements, is discussed in relation to the different anions used for crystallization. Depending on the geometry of the counteranions used (linear, bent, planar, and spherical), different molecular structures of the IM cations (rod-, V-, and U-shaped) resulted. The crystal packing in the solid-state structure is examined on the basis of a Hirshfeld surface analysis and is discussed in terms of polar and nonpolar regions

Solid-State Structures of Double-Long-Chain Imidazolium Ionic Liquids: Influence of Anion Shape on Cation Geometry and Crystal Packing

The syntheses and solid-state structures of a series of imidazolium (IM) salt-based, double C12 alkyl chain functionalized ionic liquids, namely, [C12C12IM][A], where the anion A is I−, I3−, I5−, N(CN)2−, C(CN)3−, B(CN)4−, or SbF6−, are reported. All compounds were fully characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction studies on single crystals. The molecular structure of the IM [C12C12IM]+ cation, as found in the individual crystal packing arrangements, is discussed in relation to the different anions used for crystallization. Depending on the geometry of the counteranions used (linear, bent, planar, and spherical), different molecular structures of the IM cations (rod-, V-, and U-shaped) resulted. The crystal packing in the solid-state structure is examined on the basis of a Hirshfeld surface analysis and is discussed in terms of polar and nonpolar regions

Solid-State Structures of Double-Long-Chain Imidazolium Ionic Liquids: Influence of Anion Shape on Cation Geometry and Crystal Packing

The syntheses and solid-state structures of a series of imidazolium (IM) salt-based, double C12 alkyl chain functionalized ionic liquids, namely, [C12C12IM][A], where the anion A is I−, I3−, I5−, N(CN)2−, C(CN)3−, B(CN)4−, or SbF6−, are reported. All compounds were fully characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction studies on single crystals. The molecular structure of the IM [C12C12IM]+ cation, as found in the individual crystal packing arrangements, is discussed in relation to the different anions used for crystallization. Depending on the geometry of the counteranions used (linear, bent, planar, and spherical), different molecular structures of the IM cations (rod-, V-, and U-shaped) resulted. The crystal packing in the solid-state structure is examined on the basis of a Hirshfeld surface analysis and is discussed in terms of polar and nonpolar regions

Solid-State Structures of Double-Long-Chain Imidazolium Ionic Liquids: Influence of Anion Shape on Cation Geometry and Crystal Packing

The syntheses and solid-state structures of a series of imidazolium (IM) salt-based, double C12 alkyl chain functionalized ionic liquids, namely, [C12C12IM][A], where the anion A is I−, I3−, I5−, N(CN)2−, C(CN)3−, B(CN)4−, or SbF6−, are reported. All compounds were fully characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction studies on single crystals. The molecular structure of the IM [C12C12IM]+ cation, as found in the individual crystal packing arrangements, is discussed in relation to the different anions used for crystallization. Depending on the geometry of the counteranions used (linear, bent, planar, and spherical), different molecular structures of the IM cations (rod-, V-, and U-shaped) resulted. The crystal packing in the solid-state structure is examined on the basis of a Hirshfeld surface analysis and is discussed in terms of polar and nonpolar regions

Ionic Phosphine Ligands with Cobaltocenium Backbone: Novel Ligands for the Highly Selective, Biphasic, Rhodium-Catalyzed Hydroformylation of 1-Octene in Ionic Liquids^†

The use of electron-poor phosphine-substituted cobaltocenium salts as ligands for the biphasic hydroformylation in ionic liquids has been investigated. Using improved oxidation methods, 1,1‘-bis(diphenylphosphino)cobaltocenium nitrate, 1,1‘-bis(diphenylphosphino)cobaltocenium hexafluorophosphate, and 1,1‘-bis[1-methyl(1-diphenylphosphino)ethyl]cobaltocenium hexafluorophosphate have been synthesized. 1,1‘-Bis(diphenylphosphinocobaltocenium hexafluorophosphate in particular proved to be a very suitable ligand for the biphasic hydroformylation of 1-octene in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF6), enabling high catalyst activity, high selectivity to the n-product, and no detectable catalyst leaching. In contrast to aqueous biphasic systems, the ionic liquid BMIM PF6 provides for the rhodium catalyst a low-coordinating medium with limited but sufficient solubility for 1-octene to allow high reaction rates

Solid-State Structures of Double-Long-Chain Imidazolium Ionic Liquids: Influence of Anion Shape on Cation Geometry and Crystal Packing

The syntheses and solid-state structures of a series of imidazolium (IM) salt-based, double C12 alkyl chain functionalized ionic liquids, namely, [C12C12IM][A], where the anion A is I−, I3−, I5−, N(CN)2−, C(CN)3−, B(CN)4−, or SbF6−, are reported. All compounds were fully characterized by CHN elemental analysis, 1H and 13C NMR spectroscopy, and X-ray diffraction studies on single crystals. The molecular structure of the IM [C12C12IM]+ cation, as found in the individual crystal packing arrangements, is discussed in relation to the different anions used for crystallization. Depending on the geometry of the counteranions used (linear, bent, planar, and spherical), different molecular structures of the IM cations (rod-, V-, and U-shaped) resulted. The crystal packing in the solid-state structure is examined on the basis of a Hirshfeld surface analysis and is discussed in terms of polar and nonpolar regions

Catalyst Activation and Influence of the Oil Matrix on Extractive Oxidative Desulfurization Using Aqueous Polyoxometalate Solutions and Molecular Oxygen

Our contribution describes the oxidative desulfurization of dibenzothiophene (DBT) from model oils using an aqueous H₈PV₅Mo₇O₄₀ (HPA-5) catalyst solution and molecular oxygen as the oxidant. In contrast to common oxidative desulfurization (ODS) protocols, the organic sulfur compound DBT is oxidized to water-soluble compounds, such as sulfuric acid (50–55%), sulfoacetic acid (20–25%), and sulfobenzoic acid (25–30%), which are extracted <i>in situ</i> into the aqueous catalyst phase. We describe the activating effect of oxalic acid on the ODS performance of the catalyst and propose a mechanism for the catalyst activation. Moreover, we report on the influence of various organic solvents, i.e., <i>n</i>-alkanes and aromatics, on the oxidative DBT removal. Remarkably, the rate of DBT oxidation and removal enhances with an increasing chain length of the alkane matrix, whereas aromatic compounds in the oil matrix inhibit the desulfurization rate. Moreover, we demonstrate that the aqueous catalyst phase can be reused at least 5 times without loss in catalytic performance