Modeling of adiabatic moving-bed reactor for dehydrogenation of isobutane to isobutene

The dehydrogenation of isobutane to isobutene in adiabatic radial-flow moving-bed reactors was studied. First order rate expressions were considered for the primary reaction and deactivation kinetics incorporating the reversibility of dehydrogenation reaction. Kinetic data from a fixed-bed lab-scale reactor were used for modeling of the commercial size moving-bed reactor. The model was solved numerically by dividing the reactor into differential isothermal moving-bed reactors. The conversion of isobutane to isobutene was found to be equilibrium limited in commercial-sized reactors. The model predicted the trends of conversion, temperature, and catalyst activity with conversion levels somewhat lower than observed values which was attributed to the side-reactions.

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► First-order kinetic expressions can express the trend of parameters in reactors.
► Slopes of adiabatic operating lines are underestimates due to side reactions.
► The dehydrogenation products leaving each reactor are close to equilibrium.
► Catalyst activity loss during a cycle before regeneration is large (ca. 75%).