Zeolite membrane reactors

Advanced membrane reactor systems with FAU-type zeolite membranes were described. 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 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 without the coke formation. In order to prepare Pt-loaded catalytic zeolite membranes (PtY membrane) for the selective oxidation of CO in an H2-rich mixture, FAU-type zeolite membrane was ion-exchanged and calcined in air. A mixture of CO (10000 ppm), O2 and H2 was fed to the outer surface of the membrane, and CO was selectively oxidized during its permeation through the thin layer. The PtY membrane rejected CO at a H2/CO separation factor of 10. When the O2-feed rate exceeded the CO feed rate, the CO concentration on the permeate side was decreased to less than 8 ppm. Permeation fluxes were calculated by means of a mathematical model using effective diffusion coefficients and reaction kinetics. The oxidation rates of CO were determined over a particulate catalyst that had the same composition as the PtY membrane. The predicted permeation fluxes of H2 and CO using the mathematical model were in good agreement with the experimental data.