Dedicated to Prof. Dr. Jens Weitkamp on the occasion of his 60 th birthdayData available from the literature and experimental results have shown that the distribution of the catalytic active components can be irregular already for fresh catalysts. The determination of the local concentrations of the catalytic active components using wavelength dispersive X-ray spectroscopy confirms this for microstructured wafers used in microchannel reactors. Considering this nonuniform distribution, the used model gives the relation between the local concentration profiles of the reactants inside the pores and the product yield in the entire pore. These results were used in an equation for the diffusion flux at the pore mouth, which is useful for a microchannel model developed in a recent paper [1]. The theoretical considerations deal with cylindrical pores with known reactant concentrations at the pore mouth and known distribution of the catalytic active component within the pore. Beside numerical results, some analytical solutions with low mathematical expense, applicable to special cases, are discussed. The nonconsideration of the irregular distribution of the catalytic active component can be the reason for difficulties during the extrapolation of experimental results to slightly different conditions and can have a great influence on the reaction results. The regarded examples are typical of wall-catalyzed reactions in microchannel reactors with mesopores.
In dieser Arbeit wird der Aufbau einer künstlichen Nase und deren Erprobung beschrieben. Der wesentliche Unterschied zu herkömmlichen elektronischen Nasen besteht darin, dass neben der Geruchsstoffszuordnung in Geruchsklassen auch eine Geruchsintensitätserkennung vorgenommen wird. Dazu werden die Gassensoren direkt der Geruchsfahne ausgesetzt und neben den Messsignalen der Gassensoren auch die Überströmgeschwindigkeit in den eingesetzten künstlich-neuronalen Netzen (KNN) verarbeitet. Die verwendeten Gassensoren, die elektronische Schaltung und die KNNs werden getestet.
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