Dynamic catalysis transient kinetics

The Bodenstein steady state approximation is widely applied in catalysis. At the same time this approximation is often not valid and the dynamics should be taken into accout. Transient kinetic modelling as well as oscillation reactions will be considered in Chapter 8. 

The basic ideas of the transient method applied to heterogeneous catalysis were set forth by K. Tamaru. In general, the term transient refers to changing one or more of the system parameters. In transient kinetic studies, a dynamic change is introduced into a reactor system, and the response of a reaction quantity is observed. A typical transient response experiment is sketched in Figure 8.3. 

Then, a survey of micro reactors for heterogeneous catalyst screening introduces the technological methods used for screening. The description of microstructured reactors will be supplemented by other, conventional small-scale equipment such as mini-batch and fixed-bed reactors and small monoliths. For each of these reactors, exemplary applications will be given in order to demonstrate the properties of small-scale operation. Among a number of examples, methane oxidation as a sample reaction will be considered in detail. In a detailed case study, some intrinsic theoretical aspects of micro devices are discussed with respect to reactor design and experimental evaluation under the transient mode of reactor operation. It will be shown that, as soon as fluid dynamic information is added to the pure experimental data, more complex aspects of catalysis are derivable from overall conversion data, such as the intrinsic reaction kinetics. 

Steady state and transient experiments, the substantial though fragmented literature, and new interpretations are combined in an attempt to define and understand the catalytic kinetics for crrbon monoxide oxidation over cobalt oxide (C03O4) supported on alumina. The result is a rather coherent picture of oxidation-reduction catalysis by a metal oxide. It is shown that the dynamic methods yield vastly more information than steady state studies with significantly less experimental effort. 

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Bennett, C.O., 1967. A dynamic method for the study of heterogeneous catalytic kinetics. AICHE J. 13, 890-895. Bennett, C.O., 1976. The transient method and elementary steps in heterogeneous catalysis. Catal. Rev. 13,121-148. Bennett, C.O., 2000. Experiments and processes in the transient regime for heterogeneous catalysis. In Haag, W.O., Gates, B., Knozinger, H. (Eds.), Advances in Catalysis. Elsevier Sciences, Dordrecht, pp. 329-416. 

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