LAUSR

Abstract H 2 utilization as a green energy carrier involved a growing interest towards inorganic H 2 permeable membranes, useful for its separation and purification. On this regard, Pd resulted to be the dominant membrane material due to its particular behavior to be fully H 2 perm-selective with respect to all the other gases. In the last decade, composite Pd-based membranes demonstrated their superiority over the unsupported Pd-based membranes owing to their lower cost (related to a reduced Pd content), better mechanical resistance and higher H 2 permeability. In this work, a Pd 70 -Cu 30 /γ-Al 2 O 3 membrane was prepared by metal vapor synthesis, depositing the two metals (Pd and Cu) in their active form from solvent-stabilized bimetallic nanoparticles (solvated metal atoms). An experimental campaign in terms of single gas (H 2 , N 2 , CO 2 , CH 4 ) permeation tests was carried out by varying the temperature between 300 °C and 470 °C and the feed pressure from 150 to 250 kPa. The H 2 partial pressure exponential factor (n- value ), described in the equation reporting the relationship between the H 2 permeating flux and the H 2 permeation driving force, was analyzed as a function of temperature and pressure variation. An apparent activation energy of 18.5 kJ/mol was obtained, resulting comparable to other literature data. At 400 °C and 50 kPa of transmembrane pressure, the reference H 2 /N 2 perm-selectivity was around 1800, remaining stable for around 1000 h under operation. Meanwhile, an excellent H 2 /CO 2 selectivity (6500) at the same operating conditions was reached, overcoming greatly the Robeson's upper-bound and constituting an interesting result for the application of this Pd-Cu/Al 2 O 3 membrane in pre-combustion capture. Furthermore, the effect of the thermal cycles in long-term experimental tests was also investigated and discussed.