Kinetic modeling of dehydrogenation of isobutane on chromia/alumina catalyst

The kinetics of isobutane dehydrogenation was studied on a chromia/alumina catalyst developed for fluidized-bed operation. The dehydrogenation activity measurements were carried out in a laboratory-scale plug-flow reactor at 520-580 degreesC under atmospheric pressure. Several kinetic models were derived from different mechanisms, and the suitability of the models in describing the rate of the dehydrogenation reaction was tested. The results of the kinetic modeling suggested that the rate-determining step is isobutane adsorption, possibly on a pair of chromium and oxygen ions. A satisfactory description of the reaction rate depended on inclusion of the isobutene and hydrogen adsorption parameters in the mathematical model. The activation energy of the dehydrogenation reaction was estimated to be 133-142 kJ/mol.