An improvement of the hydrogen permeability of C/Al2O3 membranes by palladium deposition into the pores

Abstract

The development of compact hydrogen separator based on membrane technology is of key importance for hydrogen energy utilization, and the Pd-modified carbon membranes with enhanced hydrogen permeability were investigated in this work. The C/Al2O3 membranes were prepared by coating and carbonization of polyfurfuryl alcohol, then the palladium was introduced through impregnation–precipitation and colloid impregnation methods with a PdCl2/HCl solution and a Pd(OH)2 colloid as the palladium resources, and the reduction was carried out with a N2H4 solution. The resulting Pd/C/Al2O3 membranes were characterized by means of SEM, EDX, XRD, XPS and TEM, and their permeation performances were tested with H2, CO2, N2 and CH4 at 25 °C. Compared with the colloid impregnation method, the impregnation–precipitation is more effective in deposition of palladium clusters inside of the carbon layer, and this kind of Pd/C/Al2O3 membranes exhibits excellent hydrogen permeability and permselectivity. Best hydrogen permeance, 1.9 × 10−7 mol/m2 s Pa, is observed at Pd/C = 0.1 wt/wt, and the corresponding H2/N2, H2/CO2 and H2/CH4 permselectivities are 275, 15 and 317, respectively.