Heterogeneous separations

Blasucd, V.M., Husain, Z.A., Fadhel, A.Z., Donaldson, M.E., Vyhmeister, E., Pollet, P., Hotta, C.L. and Eckert, C.A. (2010) Combining homogeneous catalysis with heterogeneous separation using tunable solvent systems. Journal of Physical Chemistry A, 114 (11), 3932-3938. 

Hill, E.M., Broering, J.M., Hallett, J.P., Bommarius, A.S., Liotta, C.L. and Eckert, C.A. (2007) Coupling chiral homogeneous biocatalytic reactions with benign heterogeneous separation. Green Chemistry, 9 (8), 888—893. 

Thermoregulated phase-transfer and phase-separable catalysis are attractive catalyst recycUng techniques complementing other approaches of multiphase catalysis. They utilize temperature-dependent solubility or miscibiUty phenomena to switch between homogeneous reaction and heterogeneous separation stages. 

The technique of aqueous catalytic reactions has had such an impact on the field of more general two-phase reactions that scientists have now also proposed and tested other solutions. Fluorous systems (FBS, perfluorinated solvents cf. Section 7.2) and nonaqueous ionic liquids (NAILs, molten salts cf. Section 7.3) meet the demand for rapid separation of catalyst and product phases and, owing to the thermoreversibility of their phase behavior, have advantages in the homogeneous reaction and the heterogeneous separation. However, it is safe to predict that the specially tailored ligands necessary for these technologies will be too expensive for normal applications. Compared to the cheap and ubiquitous solvent water, with its unique combination of properties (cf. Table 1), other solvents may well remain of little importance, at least for industrial applications. Other ideas are mentioned in Section 7.6. 

In this book, the focus is on rules of thumb about process equipment. Chapters 2 to 10 provide details of equipment for transportation, energy exchange, separations, heterogeneous separations, reactions, mixing, size reduction, size enlargement and process vessels, respectively. 

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