Optimization, intermediate concentration profile

Figure 5.11 presents typical concentration profiles in a PFR with cooling. As known for consecutive reactions A — P —-—> R, the maximum achievable yield in the intermediate P depends on the ratio ki/k2. There is an optimal per-pass conversion and residence time. Good selectivity may be obtained either at lower conversion with less selective catalyst, but spending more for recycles, or with more selective catalyst at higher conversion. Thus, operating the reaction system at variable per-pass conversion may be used to manipulate the selectivity pattern. 

It was concluded that this overall increase in efficiency is essentially because of thermal enhancement of subsequent oxidation reactions of the primary photoreaction intermediates. Optimization revealed that this effect is particularly significant for samples containing low concentrations of H2O2, although a large excess of H2O2 was essential for complete destruction in most experiments. The degradation profiles of the techniques used in the destruction of 4-chlorophenol are com-... 

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