Rates ten times faster for the conversion of ethylbenzene (EB) into styrene are possible over unpromoted hematite catalysts if reduction to magnetite and coking is prevented by adding traces of oxygen. This finding results from measurements made with the stagnation‐point microflow reactor shown (1: model catalyst, 2: cap, 3: diode laser).

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A vast amount of surface science experiments provides a detailed qualitative picture of the mechanisms governing the catalytic dehydrogenation of ethylbenzene (EB) to Styrene (St) over unpromoted iron oxide. Also values of kinetic and energetic parameters for adsorption and desorption are available. We present a methodology of kinetic modelling based upon this knowledge, aiming at an accurate prediction of the behaviour of the technical catalysts including deactivation and regeneration. This paper contains the detailed kinetic model and the procedure followed for determining the kinetic parameters.

Surface science methods originating from analysis of noble metal catalysts are increasingly applied to metal oxides. These methods provide direct access to fundamental structural properties and phase equilibria governing the catalytic properties of metal oxide surfaces. However, no systematic way existed so far for transferring this knowledge to technical catalysts. The aim of this paper is to combine surface science with chemical engineering methods to bridge this gap. Styrene synthesis over pure and K-doped iron oxides is used as an example to develop and to explain the methodology. Single crystal films (SCF), grown epitaxially on a Pt-carrier are considered as ideal model surfaces. Comprehensive UHV analyses yield the structural properties of SCF as well as their interaction with relevant components of the reaction mixture. Their results are combined with conversion experiments to derive a mechanistic catalyst model along with quantitative information on the reaction rates. The activity of SCF as well as their phase transitions under reactive conditions can be described with a continuum model depending on the macroscopic properties of the system. This model forms the crucial link towards technical catalysts. It is shown that the behaviour of a powder catalyst can be described as a superposition of the above kinetic model and an appropriate porous model. In this paper we review the developed methodology and conclude with the evaluation of the concept.

Edelmetallhaltige Katalysatoren werden in zahlreichen Verfahren und Prozessen der petrochemischen und chemischen Industrie sowie im Umweltschutz verwendet. Eine wichtige Anwendung ist die Reinigung von Abgasen aus Dieselmotoren von Kraftfahrzeugen mit Hilfe von Oxidationskatalysatoren. Vorgestellt wird die Reaktivabscheidung von Platin aus überkritischem Kohlendioxid auf mit Washcoat beschichteten Monolithen zur Herstellung von Katalysatoren für die Reinigung von Automobilabgasen.