Case Studies That Were Rate Limited

4 Case Studies That Were Rate Limited 

Seven commerciai case studies are presented in the next sections that describe rate-iimited processes and the strategies and soiutions to increase extrusion rates. Additionai case studies that had iimited rates and additional defects were presented in Chapters 11 and 12. 

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This might be the case since the full mercury arc was used in this series of experiments. Vibrationally nonequilibrated ethyl radicals were observed in azoethane photolysis at the shorter wavelength (5). It is expected that the rate constant for the reaction of a thermally equilibrated isobutyl radical with oxygen will be nearly equal to that for the ethyl radical. Certainly one should accept the present estimate of k7 + k as a lower limit of the value for thermally equilibrated isobutyl radicals. We plan to test the order of the reaction more extensively and redetermine k7 + kg using the flash photolysis technique employed in the methyl (21) and ethyl (5) radical studies with oxygen to shed further light on this problem. 

The absorption of ozone from the gas occurred simultaneously with the reaction of the PAH inside the oil droplets. In order to prove that the mass transfer rates of ozone were not limiting in this case, the mass transfer gas/water was optimized and the influence of the mass transfer water/oil was studied by ozonating various oil/water-emulsions with defined oil droplet size distributions. No influence of the mean droplet diameter (1.2 15 pm) on the reaction rate of PAH was observed, consequently the chemical reaction was not controlled by mass transfer at the water/oil interface or diffusion inside the oil droplets. Therefore, a microkinetic description was possible by a first order reaction with regard to the PAH concentration (Kornmuller et al., 1997 a). The effects of pH variation and addition of scavengers indicated a selective direct reaction mechanism of PAH inside the oil droplets... 

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