Phasenverhalten von hochselektiven nichtflüchtigen Flüssigkeiten mit designbarem Eigenschaftsprofil und neue Anwendungen in der thermischen Verfahrenstechnik

Abstract

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Separation of azeotropic mixtures using hyperbranched polymers or ionic liquids

“…However, the solution viscosities are still far below the acceptable distillation limit of 100 mPa s −1 , a barrier above which the number of required transfer units drastically increases and the manageability of the separation becomes increasingly difficult (Böcker and Ronge, 2003). At 343 K (that is, more than 50 K below the bottom temperature and more than 15 K below the temperature at the entrainer feed stage of the main column), the dynamic viscosity of a binary PG–water solution amounts to 70 mPas at 70 wt % PG (Seiler et al, 2004). The solution viscosity of the [EMIM] + [BF 4 ] − –water solution is even smaller (Jork et al, 2003b).…”

“…Both distillation columns do not require a rectifying section. The purification of the extract and the raffinate could also be achieved by combining the extraction unit with crystallization steps (Seiler et al, 2004).…”

“…Because the polarity of hyperbranched macromolecules can be adjusted by their functional end groups, selective solvents (consisting of either pure hyperbranched polymers or fractions of hyperbranched polymers) can be designed. Unlike the conventional linear polymers, hyperbranched polymers not only show a remarkable selectivity and capacity (Seiler et al, 2003a; Seiler, 2004), but, because of a lack of chain entanglements, also a comparatively low solution and melt viscosity (Hult et al, 1999; Kim, 1998; Mourey et al, 1992; Pirrung et al, 2002; Wooley et al, 1994) as well as an enormous thermal stability (Hult et al, 1999; Kim et al, 1990). Therefore, hyperbranched polymers can be used for the optimization of a number of separation and production processes.…”

“…Therefore, hyperbranched polymers can be used for the optimization of a number of separation and production processes. Seiler and Arlt suggested the use of hyperbranched polymers as entrainers for extractive distillation and as selective solvents for liquid–liquid extraction (Arlt et al, 2001a; Seiler, 2002a; Seiler et al, 2004). Furthermore, the use of hyperbranched polymers as selectivity‐ and capacity‐increasing solvent additives for absorption processes, as stationary phases for analytical and even preparative chromatography, and as carriers for the controlled release of drugs seems promising (Seiler et al, 2002d; Seiler, 2004).…”

Transesterification of methylsulfate and ethylsulfate ionic liquids—an environmentally benign way to synthesize long-chain and functionalized alkylsulfate ionic liquids

“…In order to shift the equilibrium of the transesterification reaction towards the desired products, ethanol (or methanol) liberated in the transformation must be efficiently removed, a well-known procedure in transesterification reactions. One main problem we encountered during the investigation of this specific aspect was the fact that components such as alcohols show different vapour pressure when dissolved in ionic liquids (a fact that is technically used in extractive distillation with ionic liquids being used as entrainer fluids 28 ). The strong interactions between the ionic liquids and the highly polar methanol or ethanol decrease the vapour pressure of these short chain alcohols significantly.…”