Adolfo Iulianelli, Giuseppe Bagnato, Angelo Basile Pd-alloy supported membranes: hydrogen separation/purification and membrane reactor applications Adolfo Iulianelli, Giuseppe Bagnato, Angelo Basile Institute on Membrane Technology of the Italian National Research Council (ITM-CNR), Via P. Bucci Cubo 17/C c/o University of Calabria, Rende (CS), 87036 – Italy; a.iulianelli@itm.cnr.it; +39 0984 492011 SEPARATION TECHNIQUES 2016 – Valencia, September 26-28, 2016

Membranes for H2 separation Polimeric Microporous Metallic Carbon Ceramic Temperature range < 200 °C 200 – 600 °C 300 – 600 °C 500 – 900 °C 600 – 900 °C aH2/N2 low 5 – 139 > 1000 4 – 20 > 100 Stability issues Swelling, mechanical strenght Stability in H2O Phase Transition Brittle, Oxidization Stability in CO2 Poisoning issues HCl, SOx H2S, HCl, CO Strong adsorbing vapours, organics H2S Material Polymers Silica, Alumina, Zirconia, Titania, Zeolite Palladium, Palladium Alloy, etc. Proton Conductivity ceramics (mainly SrCeO3-d, BaCeO3-d) aH2/N2 = permeanceH2/permeanceN2

Pd-based composite membranes: the best compromise A = Intermediate region; B = High H2 ideal selectivity and permeance; C = Low H2 ideal selectivity and permeance; S. Yun, S. Ted Oyama / Journal of Membrane Science 375 (2011) 28–45

Supported Pd-Au/PSS : fabrication & performance Housing a tubular Pd-Au/PSS membrane (5 wt% of Au), with 7 μm of thickness, 10 mm of O.D., 150 mm of total length (12 mm active length) and closed at one end. ELP

He leak tests on the Pd-Au/PSS membrane at room temperature He leak testing at room temperature

Steady state conditions PH2 the hydrogen permeance, pH2,reaction and pH2,permeate the hydrogen partial pressures in the reaction and permeate sides, respectively. n is variable in the range 0.5 - 1 depending on the rate limiting step of hydrogen diffusion

Steady state conditions

S. Yun, S. Ted Oyama / Journal of Membrane Science 375 (2011) 28–45

Supported Pd-Au/PSS : application in membrane reactor for methane steam reforming reaction T = 420 °C Ni/Al2O3 catalyst MR TR A. Iulianelli, M. Alavi, G. Bagnato, S. Liguori, J. Wilcox, M.R. Rahimpour, R. Eslamlouyan, B. Anzelmo, A. Basile, Supported Pd-Au membrane reactor for hydrogen production: membrane preparation, characterization and testing, Molecules, 21 (2016) 581-594

Critical issue: coke formation CH4 detected inside the lumen of the membrane reactor Before reaction tests After reaction tests

Supported Pd/PSS membrane: fabrication & performance A bare support (PSS); B oxidized support; C g-alumina layer; D activated layer; E Pd-layer 10 mm thick Ideal selectivity [α (H2/N2)] = H2 permeance/N2 permeance He permeance at room temperature α (H2/N2) > 10,000 (T = 400 °C) S. Liguori, A. Iulianelli, F. Dalena, P. Pinacci, F. Drago, M. Broglia, Y. Huang, A. Basile, Performance and long-term stability of Pd/PSS and Pd/Al2O3 for hydrogen separation, Membranes, 4 (2014) 143-162.

He permeance at room temperature Supported Pd/PSS Supported Pd-Au/PSS 2.0E-05 α (H2/N2) > 10,000 (T = 400 °C) α (H2/N2) < 1,000 (T = 420 °C)

Supported Pd/a-Al2O3 : fabrication & performance ELP SEM image of the cross section of the composite Pd/Al2O3 membrane (a); morphology of the Pd-surface (b). Pd - layer = 5/6 μm, Support: a-Al2O3

Supported Pd/a-Al2O3 : pure gas permeation tests DOE Target: aH2/N2 = 104 Membrane failure

Fick-Sieverts law

A. Iulianelli, V. Palma, G. Bagnato, C. Ruocco, Y. Huang, G. Vitulli, E. Macchia, N.T. Veziroğlu, A. Basile, From industrial bioethanol to high grade hydrogen generation: steam reforming reaction promoted by a novel Co-Pt catalyst in a H2-full perm-selective Pd-based membrane reactor, submitted to Journal of Power Sources.

Supported Pd/a-Al2O3 : application in membrane reactor for methane steam reforming reaction Ni/Al2O3 catalyst H2-purity > 99.5%

Supported Pd/a-Al2O3 : critical issues Membrane failure

Supported Pd-Cu/g-Al2O3 – SiO2: fabrication & performance Pd65%-Cu35% dense layer ~ 20 mm Metal vapour synthesis

Conclusions In composite Pd and Pd-alloy membranes, the role of the intermediate layers and the preparation technique as well play a critical role, determinig the membrane performance in terms of hydrogen separation (perm-selectivity and purity). Ceramic supports are preferred material with respect to porous stainless steel. Among ceramic supports, a-Al2O3 has to be preferred to g-Al2O3. Pure Pd-based membranes seem to be more effective than Pd-alloy ones, even though the latter constitute better solutions for potential attack of H2S (Pd-Au and Pd-Cu based). Pd and Pd-alloy membranes, applied to membrane reactors (methane steam reforming), allow interesting performance in terms of H2 purity and recovery, but they suffer the coke formation and the thermal cycles.

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