Dual bed catalyst system for oxidative dehydrogenation of mixed-butenes: a synergistic mechanism

Abstract

Oxidative dehydrogenation (ODH) of mono and mixed-butenes to 1,3-butadiene (BD) was conducted using individual and dual bed catalyst systems, consisting of ZnFe2O4, Co9Fe3Bi1Mo12O51 or both. The dual bed catalyst system gave improved catalytic performance. A mechanism based on synergy between the catalysts is proposed to explain the improved overall butene conversion. The proportion of the reactants differed between the catalyst beds in the dual bed system, making better use of the catalytic activity of the second bed. The existence of all butene isomers inhibited isomerization, leading to a higher proportion of ODH reactions and thus improved the conversion of butene and the yield of BD. The packing sequences and the volume ratio of the catalysts in the bed were optimized. The results indicated that the sequence with ZnFe2O4 on top and a catalyst packing ratio of between 4:6 and 6:4 led to better activity.