OTKA Project No.: T 037241

Formation of active sites of metal catalysts; effect of additives

The effect of the most important astoichiometric component, hydrogen will be investigated on the reactions of model hydrocarbons over unsupported metal catalysts in the pressure range from a few mbar to >1 bar. In addition to the well-known Pt catalyst, Pd, Rh, Ir will be studied. We shall prepare bimetallic catalyst combinations, using reduction in microemulsions, metal adsorption, electrolytic method and acetic acid as the reducing agent. The second metal will form a surface layer on particles, except for the microemulsion method. The catalytic properties of the system will be studied (to decide if additivity is valid or if entirely new active ensembles will be produced in the bimetallic system). Further, we shall study their stability after their treatment with hydrogen or oxygen as well as under catalytic conditions. Selected model hydrocarbons will be used, to simulate reactions of naphtha reforming under laboratory conditions. These reactions are accompanied by assumulation of carbonaceous deposits ("carbon"). Its amount and chemical state will be investigated after reaction and/or intentional deactivation by electron spectroscopy and/or radioactive tracer studies. The results will be compared to those obtained over supported model catalysts, in order to clarify the effect of support, method of preparation and additives influencing the size and structure of active ensembles.