PREPARATION, CHARACTERIZATION AND CATALYTIC TESTING OF COBALT OXIDE AND MANGANESE OXIDE CATALYSTS SUPPORTED ON ZIRCONIA

Zirconia-supported dehydrogenation catalysts based on manganese oxide and cobalt oxide were investigated. Preparation of zirconia-supported Mn(-K) and Co(-K) catalysts was carried out by (co-) impregnation of z irconia pellets to incipient wetness. Characterization of the fresh ca talysts was performed using nitrogen adsorption, electron microscopy ( TEM), X-ray diffraction (XRD), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The dehydrogenation of I- butene was used as a catalytic test reaction. It was shown that cataly sts containing finely divided cobalt oxide or manganese oxide homogene ously distributed over zirconia supports can be prepared using a pre-s haped zirconia support. From the results obtained with various charact erization techniques it was concluded that preparation using complex o rganic precursors results in the best dispersion of the active phase. The metal-EDTA complex seems the most suitable for producing the desir ed catalyst systems. Catalysts without potassium carbonate deactivate due to carbon deposition. The deactivation behaviour of supported coba lt oxide is similar to that of supported iron oxide, while supported m anganese oxide shows a more gradual deactivation. The Mn- or Co-based catalysts containing potassium carbonate did not show deactivation up to at least 10 h on stream. The activity and selectivity are different , however. The activity ranking was found to be Fe,K > Mn,K > Co,K. Th e selectivity of the manganese oxide-based system was found to be high er than in the iron oxide-based catalyst.