Oxidative dehydrogenation of isobutane on Cr–Ce–O oxide:: I. Effect of the preparation method and of the Cr content Original Research Article

The Cr–Ce–O catalysts of different Cr content have been synthesised using co-precipitation or impregnation techniques, and tested in the oxidative dehydrogenation of isobutane. The Ce–-Cr–O system has already been found to be active and selective in this reaction at low temperatures around 270°C, with the selectivities to isobutene of about 60% at 10% isobutane conversion and a maximum yield of isobutene of about 8%. The total specific activity increases with the increase in the Cr content to a constant value observed for the samples prepared by precipitation at Cr/Ce ratio equal to 1, and those obtained by the impregnation at the Cr content of 10 At Cr nm−2. The maximum specific activity does not depend considerably on the preparation technique, slightly higher yields are found, however, for the samples prepared by impregnation. Nevertheless, the co-precipitation technique leads to the less reproducible catalysts in which the potassium impurity may exert a poisoning effect.