MATHEMATICAL ANALYSIS ON CATALYTIC DEHYDROGENATION OF CYCLOHEXANE USING MICROPOROUS MEMBRANE

Abstract

A steady state, isothermal one dimensional mathematical model has been developed for dehydrogenation of cyclohexane carried out in a microporous membrane reactor. The performance of three reactor configurations viz. conventional fixed bed, full length membrane reactor and hybrid reactor have been studied at two feed conditions: one is without hydrogen and the other is with hydrogen. Hydrogen has been added co-feed to increase the stability of catalyst and membrane and to reduce the possibility of coking. FAU type zeolite microporous membrane has been used. The expressions which relate permeance of components through FAU type membrane to temperature have been formulated on the basis of experimental data available in open literature. The model equations have been solved by using MATLAB. The simulated results at a given set of operating conditions and boundary conditions have been found to be in good agreement with the experimental results. The variation in conversion along the length of the reactor and with temperature has been studied for all three reactor configurations and feed conditions. This study reveals that the conversion is maximum in full length membrane reactor and minimum in fixed bed reactor. The conversion in hybrid reactor has been found to be in between fixed bed and full length membrane reactor. On being endothermic reaction the conversion increases with temperature. Although the conversion is lower in hybrid reactor than full length membrane reactor the performance of hybrid reactor may be considered superior at the expense of high cost and high reactant loss in full length membrane reactor. In case of co-feeding of hydrogen with cyclohexane, the conversion in all cases is lower than without hydrogen due to high hydrogen concentration in the reactant. This reduction in conversion may be accepted on commercial level in order to maintain stability of membrane and catalyst