Catalyst diversity

Every model has limitations. Even the most robust and best-validated regression model will not predict the outcome for all catalysts. Therefore, you must define the application domain of the model. Usually, interpolation within the model space will yield acceptable results. Extrapolation is more dangerous, and should be done only in cases where the new catalysts or reaction conditions are sufficiently close to the model. There are several statistical parameters for measuring this closeness, such as the distance to the nearest neighbor within the model space (see the discussion on catalyst diversity in Section 6.3.5). Another approach uses the effective prediction domain (EPD), which defines the prediction boundaries of regression models with correlated variables [105]. 

Lennon IC, Pilkington CJ. The application of asymmetric hydrogenation for the manufacture of pharmaceutical intermediates the need for catalyst diversity. Synthesis 2003 1639-1642. 

As depicted in Figure 4.13, HREM images provide a direct visualisation of the particles present in a supported catalyst Diverse parameters of these particles can be... 

The discovery that the protonated forms of zeolites could be used as active, stable and shape selective catalysts in hydrocarbon transformations has been of immense benefit to the refining and petrochemicals industry. The need for optimised microporous acid catalysts will continue as fuel specifications change and the requirements of the chemicals market shift. The likely growth in demand for synthetic fuels, including diesels, is one expected trend that could involve zeolite catalysts. Diverse feedstock chemicals and fine chemicals synthesis involving zeolite catalysts are also being developed. 

Finally, the overall results of running the genetic algorithm for all 96 value combinations of the adjustable parameters are summarised in Table 7.3 (convergence of the algorithm) and Table 7.4 (decrease of catalyst diversity). In Table 7.3, the following indicators of convergence have been used ... 

According to the concept of asymmetric activation, a chiral molecule (activator) is able not only to selectively activate one enantiomer of a racemic chiral catalyst but also to make the enantiopure catalyst even more efficient, that is, to produce a higher enantiomeric excess in the product than can the enantiomerically pure catalyst on its own [3, 11]. On the basis of this concept, Mikami and coworkers [29] have successfully applied the combinatorial approach to the discovery of highly enantioselective catalysts for addition of diethylzinc to aldehydes, via screening of the catalyst diversity generated by a combination of chiral ligand and activator... 

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