The Effect of Transition Alumina (γ‐, η‐, χ‐Al2O3) on the Activity and Stability of Chromia/Alumina Catalysts. Part II: Industrial‐Like Catalysts and Real Plant Aging Conditions

The effect of alumina structure (γ‐, η‐, χ‐Al2O3) on the long‐term stability of industrial‐like Cr2O3/Al2O3 dehydrogenation 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‐Al2O3 is the most stable against irreversible deactivation, whereas χ‐Al2O3 is 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‐Al2O3 is the most aging‐resistant catalyst in an industrial dehydrogenation reactor.