PREPARATION, CHARACTERIZATION AND TESTING OF TITANIA-SUPPORTED IRON-OXIDE BASED DEHYDROGENATION CATALYSTS

Iron oxide-based catalysts supported on titania and zirconia have been investigated as alternatives for the currently used bulk iron oxide d ehydrogenation catalysts. The present study focuses on titania-support ed catalysts. Catalyst samples were prepared by pore-volume impregnati on of commercially available pre-shaped support bodies with solutions of various iron precursor compounds, Transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) revealed that the bes t microscopic distribution is achieved with ammonium iron citrate. X-r ay diffraction (XRD) showed a difference between the investigated supp orts: on rutile TiO2, iron was present as hematite (Fe2O3), whereas on anatase, pseudobrookite (Fe2TiO5) was formed. When testing the cataly tic activity in but-1-ene dehydrogenation, rapid deactivation was obse rved which could not be prevented by using a catalyst containing potas sium. Without potassium, deactivation is attributed to the formation o f ilmenite, FeTiO3. With potassium, the iron oxide phase reacts with b oth potassium and TiO2, which diminishes the activity which initially was present in catalysts without potassium. When a more inert support is used, viz. ZrO2, no solid state reaction is observed, and a stable catalyst is obtained.