Prognose des Diffusionsverhaltens von dreikomponentigen Systemen bei heterogenen Gasreaktionen mit Hilfe neuartiger Diagramme

Abstract

In the industrial application of porous catalysts for gas reactions, gas mixtures of three or more components are usually encountered. How can their diffusional behaviour be modelled? How good an approximation is the simple Fick's law without Stefan flow? A method is presented which provides a general answer to these questions, based on a type of "principle of corresponding states" for the interdependence of the diffusion coefficients. -Two practical examples are chosen for illustration. Firstly, it is shown that diffusional balances -contrary to the theoretical results of other authors -can also be quite non-linear. However, in most cases, they are nearly linear. -Secondly, it is pointed out that this allows a substantial simplification in the modelling of three component reactions using the results from two component systems with volume change. The volume change modulus for the latter case can be modified for use in three component systems and it is pointed out when special attention to this modulus is necessary.