In situ characterization of carbonaceous deposits formed on chromia/zirconia during isobutane dehydrogenation

The formation of carbonaceous species during isobutane dehydrogenation on chromia/zirconia was studied by in situ diffuse reflectance Fourier transform infrared spectroscopy combined with mass spectrometry for on-line product gas analysis. The reactions of the hydroxyl groups of zirconia support with the hydrocarbons and the reduction of the chromates resulted in the formation of adsorbed acetone, formate and acetate. However, they were suspected not be involved in the dehydrogenation. The reduced chromia/zirconia catalysts were active in the dehydrogenation of isobutane but deactivated due to formation of coke. These unsaturated/aromatic hydrocarbon species were suggested to form through the adsorbed dehydrogenation intermediates or products.