Abstract: Porous Pd/α-Al2O3 catalytically active membrane was prepared by microemulsion and impregnation techniques. Palladium nanoparticles in the microemulsion and in the pore structure of α-Al2O3 membrane were characterized by transmission electron microscopy, scanning electron microscopy, andX-raydiffraction. The results show that the palladium nanoparticles dispersed in microemulsion are evenly immobilized in the pore structure of the membrane in the form of palladium crystalline particles with several hundred nanometers by impregnation. The catalytic activity and selectivity of porous Pd/α-Al2O3 active membranes were investigated for the hydrogenation of1,5-cyclo-octadiene (COD) in a catalytic membrane contactor and were compared with the Pd-polyacrylic acid (PAA) membrane reactor (MR), slurry reactor, and fixed-bed reactor (FBR). The results show that both reaction rate of COD and selectivity for 1-cyclo-octene in Pd/α-Al2O3 MR are considerably improved compared with Pd-PAA MR and FBR. The effects of Pd/α-Al2O3 MR in facilitating mass transfer and in eliminating diffusion inside the pores are remarkable. This can be attributed to the distribution of palladium in the membrane structure and the high flow rate of reactants in the membrane pores.

Key words: palladium, alumina, catalytically active membrane, membrane reactor, 5-cyclo-octadiene, selective hydrogenation, microemulsion