Catalytic dehydrogenation of cyclohexane in an FAU-type zeolite membrane reactor

An FAU-type zeolite membrane was formed on a porous α-Al2O3 support tube, for use in the selective separation of benzene and hydrogen from cyclohexane. The membrane was used for the catalytic dehydrogenation of cyclohexane in a membrane reactor packed with a Pt/Al2O3 catalyst. The reaction was carried out in the temperature range of 423–523 K over a 1.0 wt.% Pt/Al2O3 catalyst prepared by means of an impregnation method. The activity of the catalyst was evaluated in a conventional packed bed and no significant deactivation was found after at least 3 days of use. The conversion of cyclohexane in the membrane reactor increased beyond the thermodynamic equilibrium value due to the simultaneous removal of hydrogen and benzene from the reaction site. The conversion of cyclohexane increased with increasing sweep flow rate, which can be attributed to the fact that the rapid removal of products leads to a high turnover rate. In addition, a decrease in the feed rate of cyclohexane led to a higher cyclohexane conversion. When the sweep flow rate was maintained at 100 cm3 (STP) min−1 and the cyclohexane feed rate was maintained at 1.1 mol h−1, the conversion of cyclohexane in the FAU-type zeolite membrane reactor reached 72.1% at 473 K, compared to the calculated equilibrium value, 32.2%.