Simulation of Catalytic Dehydrogenation of Cyclohexane in Zeolite Membrane Reactor

Abstract

A mathematical model is presented to investigate the performance of tubular catalytic membrane reactor for dehydrogenation of cyclohexane using a FAU type zeolite membrane. The empirical correlations for the permeance of cyclohexane, benzene and hydrogen through FAU type zeolite membrane as a function of temperature have been developed. Three reactor configurations have been considered: conventional fixed bed, full length membrane reactor and hybrid reactor. The reactor performance has been studied in terms of conversion of cyclohexane to produce hydrogen. The observed conversions are ranked in the order: full length membrane reactor > hybrid reactor > fixed bed reactor. The simulation studies have been carried out for two feed conditions: one with hydrogen and another without hydrogen. The effect of cofeeding of hydrogen, sweep gas flow rate variation, and dilution ratio on the conversion of cyclohexane has been investigated in detail. The maximum percent increase in conversion of cyclohexane has been obtained at 473 K in hybrid as well as in membrane reactor. This temperature is also found to be optimum for sweep gas flow rate of 4.5 x 10-5 mol s-1. The conversion is observed to be suppressed by cofeeding of hydrogen and percent reduction is lowest at high temperature of 490 K in membrane reactor. The enhancement in the conversion is observed as a consequence of dilution of the feed with inert gas. The results reveal that hybrid reactor is not necessarily a better choice than the full length membrane reactor. However, at the expense of loss of reactant, hybrid reactor is better than full length membrane reactor.