1. 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), – Italy;
SEPARATION TECHNIQUES 2016 – Valencia, September 26-28, 2016

2. 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

3. 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

4. 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

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

6. 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 depending on the rate limiting step of hydrogen diffusion

7. Steady state conditions

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

9. 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)

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

11. 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)

12. 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)

13. 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

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

15. Fick-Sieverts law

16. 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.

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

18. Supported Pd/a-Al2O3 : critical issues
Membrane failure

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

20. 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.

21. Institute on Membrane Technology
ITM-CNR
Institute on Membrane Technology
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