Catalytic dehydrogenation of propane in hydrogen permselective membrane reactors

Propane dehydrogenation was studied in hydrogen permselective packed-bed membrane reactors and conventional packed-bed reactors. Two different types of developmental membranes were investigated: microporous silica-based membranes and a palladium thin film supported by a porous ceramic substrate. The membrane reactors were operated at liquid hourly space velocities (LHSVs) similar to those used in commercial reactors for propane dehydrogenation. Although the initial hydrogen permselectivity of the palladium membrane was substantially higher than that of the silica-based membranes, this membrane deactivated and eventually failed after several hours of exposure to reaction conditions. Moderate improvements in propylene yield were obtained with the silica-based membrane reactors. A propylene yield of 39.6% was obtained at an LHSV of 3 and a temperature of 823 K compared to a yield of 29.6% in a conventional packed-bed reactor operated with the same flow rate. The reaction selectivity for propylene was generally above 97 mol % in both the conventional and membrane reactors, however, catalyst deactivation rates were generally higher in the membrane reactors.