Rh-modified alumina membranes: preparation, characterization and reaction studies Original Research Article

The Rh-modified γ-Al2O3 membranes were prepared by two ways. The pore size distribution demonstrates that, after addition of a small amount of rhodium to the boehmite sol, the structure of γ-Al2O3 membrane still remains intact. The mean pore diameter remained at about 3 nm. Meanwhile, Rh-modified γ-Al2O3 membrane exhibited a much higher separation factor of H2/Ar than pure γ-Al2O3 membrane in the range of 100–350°C. In addition, the Rh-modified γ-Al2O3 membranes were applied to the membrane reactors of ethanol dehydrogenation, and the effects of the temperature and flow rate of sweeping argon on ethanol conversion were investigated. The results showed that the ethanol conversion and the selectivity of acetaldehyde in the Rh–Al2O3 membrane reactor were higher than those in Al2O3–Rh membrane reactor, owing to the formerʹs higher hydrogen permeability and separation factor in the range of experimental temperature. The reduction temperature and hydrogen adsorption properties of Rh-modified alumina membrane were measured by TPR and TPD separately; the morphology and structure of the membrane were characterized by SEM, TEM and XRD, respectively.