A comparative evaluation of the hydrogen separation, purification and transport behavior of α-alumina membrane and γ-alumina membranes modified with ALOOH sol.
The main purpose of this work is to investigate the hydrogen permeation behavior of a commercial ceramic alumina membrane and compare same with that of a γ-alumina membrane graded with an AlOOH sol using the dip coating method. The permeance of hydrogen and 5 other single gases (He, N2, CH4, CO2 and Ar) were investigated at high temperatures. Mixed gas permeation tests for a H2 gas mixture were also carried out. Results showed that the permeance of H2 increased with increasing temperature for the graded γ- Al2O3 membrane while it decreased for the α-Al2O3 support. For the single gas tests, the α-Al2O3 support show higher permeance of up to 9.45 x 10-3 mol m-2 s-1 Pa -1 compared to 1.03 x 10-3 mol m-2 s-1 Pa-1 for the γ-Al2O3 but the graded substrate was permeable to only H2 at fifth coating. The mixed gas tests for a gas mixture (H2= 50%, CO= 28%, CO2=10% CH4=8%, N2=4%) show lower H2 permeance which was attributed to the inhibition effect of CO2 in the gas mixture. The H2/N2 permselectivity for both membranes was close to the theoretical Knudsen value of 3.73 which suggests a combined viscous and Knudsen flow transport mechanism
