Method-operable design region

ATP Verification Studies and Establishment of the Method Operable Design Region... 

The performance of a chemical plant depends upon an enormously high number of design and operating variables. This great number of process variables makes it impossible to find optimal conditions within the region of safe operation if no quantitative relationships (defined in terms of mathematics) between performance indices and process variables are known. In general, optima are complex functions of process variables, and therefore quantification of experimental ressults is needed. The methods for scale-up that were conventionally used at the time of Perkin chemistry resulted in successful commercialization of many laboratory recipes. This evolutionary, step-by-step method of scale-up is illustrated in Fig. 5.3-1 (after Moulijn et al. 2001). 

In the results just discussed, the attempt was to determine conditions for equal performance, from which regions of relative superiority of either reactor could be identified. Moreover, the relationship between the location of this boundary and some key parameters has been studied. It is difficult to show the location of the boundary using two- or three-dimensional plots. The most practical method would be to optimize a process for a defined set of model parameters with respect to design and operating conditions, and to compare optima for the MR and the TBR to find which of the two is superior. 

The characteristics of limited operating regions, substrate or product inhibition, and reactions in aqueous solutions have often been considered as the most serious drawbacks of biocatalysts. Many of these drawbacks, however, turn out to be misconceptions and prejudices.For example, many commercially used enzymes show excellent stability with half-lives of months or even years under process conditions. In addition, there is an enzyme-catalyzed reaction equivalent to almost every type of known organic reaction. Many enzymes can accept non-natural substrates and convert them into desired products. More importantly, almost all of the biocatalyst characteristics can be tailored with protein engineering and metabolic engineering methods (refer to the section Biocatalyst Engineering and see also the entry Protein Design ) to meet the desired process conditions. 

---