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The effect of alumina structure (γ‐, η‐, χ‐Al2O3) on the long‐term stability of industrial‐like Cr2O3/Al2O3dehydrogenation catalysts under industrial dehydrogenation conditions is studied. It is shown that the type of alumina support determines physicochemical and catalytic stability of the catalyst: η‐Al2O3is the most stable against irreversible deactivation, whereas χ‐Al2O3is the least stable. One of the possible reasons of predominant stability of η‐Al2O3‐based catalyst is its relatively high sintering stability under real plant conditions. High‐temperature (>800 °C) calcination, sometimes used to compare stabilities of chromia/alumina catalysts, appears to be unable to simulate industrial aging because of the inconsistency of the phase composition of industrially and artificially aged catalysts. Alumina supports (γ‐, η‐, χ‐Al2O3) of chromia/alumina dehydrogenation catalysts with industrial‐like chromia loading affect the structural and catalytic stability under industrial dehydrogenation conditions. It is shown that apart from the stability pattern of the catalysts under artificial aging conditions such as high‐temperature (>800 °C) calcination where γ‐Al2O3‐based catalyst is the most stable one, Cr2O3/η‐Al2O3is the most aging‐resistant catalyst in an industrial dehydrogenation reactor.

The effect of transition alumina (γ‐, η‐, χ‐Al2O3) on the activity and stability of model chromia/alumina catalysts with 4 wt% Cr in isobutane dehydrogenation is studied. It is shown that a fresh catalyst with η‐Al2O3as a support has the highest activity, while with χ‐Al2O3has the lowest one. The characterization of the catalysts by N2adsorption, X‐ray diffraction (XRD), electron spin resonance (ESR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS) is used to describe changes in the catalysts induced by high‐temperature treatment at 800, 1000, and 1200 °C in air. It is shown that sintering of the alumina support and formation of chromia‐alumina solid solutions are the reasons of irreversible decline in the catalytic activity. Cr/γ‐Al2O3is found to be the most stable to sintering and phase transformation, whereas Cr/χ‐Al2O3is found to be the least stable. Due to its highest initial activity, the η‐Al2O3‐supported catalyst loses its dehydrogenation activity most rapidly as the calcination temperature is raised. The segregation of sodium impurities is observed in the course of heat treatment, which may be an additional cause of deactivation. Alumina supports of chromia‐alumina dehydrogenation catalysts not only provide different catalytic activity of the as‐prepared catalysts but also exert an effect on their thermal stability. The intensity of Cr/Al2O3irreversible deactivation upon high‐temperature heat treatment in air lowers from Cr/χ‐Al2O3through Cr/η‐Al2O3to Cr/γ‐Al2O3, revealing a pronounced structural stability of the γ‐Al2O3‐based catalyst.