Reaction Engineering Aspects

The reaction engineering aspects of liquid-liquid reactions have been well studied ([86-88], cf. Section 4.1). The performance of these reactions depends on the hydrodynamics of the dispersion, the mixing of the two fluid phases, the interface mass-transfer steps, the phase equilibria and kinetics of the reactions involved. 

Some of the examples presented in Section 4.2.2 are, however, not only restricted to the two liquid phases discussed, but contain in addition a further gas phase [89]. For instance, in hydroformylation a water-gas phase exists, in oligomerizations an ethylene phase and in telomerizations a butadiene phase. For these gas-liquid-liquid systems there is so far only a limited amount of published information on the reaction engineering aspects [90]. One exception is the study of 1-oc-tene hydrogenation using a rhodium/TPPTS catalyst [91], in which both thermodynamics and kinetics have been investigated in some detail. The same group also studied the hydroformylation of 1-octene [92]. 

Some further special technical aspects should be mentioned. The intensive mixture of the two liquid phases is an important condition for obtaining high reaction rates. This mixing can be achieved in bubble columns, tray columns or in stirred-tank reactors. In the few publications on industrially realized two-phase reactions the stirred tank reactor is always cited, but without detailed information on the stirring device. One further possible way to increase the mass transfer between the two liquid phases is by the influence of sonification. Cornils et al. applied this technique in the hydroformylation of hexene or diisobutene and found a considerable increase in the turnover numbers [93]. Another possibility for increasing the mass transfer may be by the use of microemulsions and micellar systems [94], which can be reached by addition of certain surfactants. This aspect is discussed in Sections 3.2.4 and 4.5. The separation of catalyst compounds in two-phase systems in combination with membranes has been studied recently by Muller and Bahrmann [95], 

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Mechanochemical and chemical reaction engineering aspects in the break down of turbulent drag reduction of cationic surfactant solutions... 

Transport properties and reaction engineering aspects of F-T synthesis have been the subject of comprehensive reviews, e.g., Kolbel and Ralek (1980), Anderson (1984), and Saxena et al. (1986). Readers are referred to these references for details on the F-T synthesis and the extensive literature listings contained in them. 

Chemical Reaction Engineering Aspects of Homogeneous Hydrogenations... 

Chemical Reaction Engineering Aspects of Homogeneous Hydrogenations Using these definitions, Eq. (1) can be rewritten as Eq. (4) ... 

The reaction engineering aspects of these polymerizations are similar. Excellent heat transfer makes them suitable for vinyl addition polymerizations. Free radical catalysis is mostly used, but cationic catalysis is used for non-aqueous dispersion polymerization (e.g., of isobutene). High conversions are generally possible, and the resulting polymer, either as a latex or as beads, is directly suitable for some applications (e.g., paints, gel-permeation chromatography beads, expanded polystyrene). Most of these polymerizations are run in the batch mode, but continuous emulsion polymerization is common. 

K. VandenBussche, Reaction engineering aspects of the Sintef-UOP combinatorial chemistry effort, CPAC Summer Instimte meeting July 2001. 

The more challenging forms of tissue culture involve two or more types or animal cells grown simultaneously. Good progress has been made on skin replacements with products approved by the FDA Administration. Martin and Vermette (2005) discuss the reaction engineering aspects of tissue culture and conclude that the womb with its good mass transfer and essentially zero shear is ideal for growing complicated structures. 

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