Cascades multicomponent mixture separation

Cascades for multicomponent mixture separation involving other separation processes... 

The isolation of paclitaxel exemplifies that most preparative separations must be downsized to a level where a limited number of individual compounds are present to ease the final purification steps. This downsizing of the separation problem can be done by crude separations or by a cascade of consecutive chromatographic separation steps. One finally ends up at a point where a multicomponent mixture with a broad concentration range of the different substances has to be fractionated to a series of mixtures. This approach is described in Fig. 4.4. In general, a mixture can be split into three types of fractions, which each represent a specific separation problem. These three fractions exemplify possible separation scenarios that differ with regard to the ratio of target products and impurities. 

Large-scale utilization of a cascade of separation devices of one particular type for the separation of a multicomponent mbrture is primarily found in the case of distillation based separation of a multicomponent mixture of volatile chemicals (see Section 9.2). We refer here to steady state operation of these distillation devices since chromatographic operation separates a multicomponent mixture generally... 

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