(608c) Synthesis & Performance Study of Pd-Au/PSS Membrane Reactor to Produce Highly Pure Hydrogen Via Natural Gas Steam Reforming

One possible use of hydrogen, without direct greenhouse gas emissions, is as feed for a fuel cell (FC), with the most readily available technology being a proton exchange membrane FC (PEMFC). In order to avoid poisoning of PEMFC’s Pt-based catalyst due to the presence of ppm levels of CO, the hydrogen feed needs to be ultra-pure. The industrial process for hydrogen production, which is a multi-step energy-intensive process followed by further separation/purification, can be a potential source [1]. However, as an alternative method, a Pd-based membrane reactor (MR) may be used due to its ability to provide high-purity hydrogen directly. Moreover, the MR works at milder operating conditions compared to a traditional system.

In recent years, Pd-based composite membranes, i.e., thin metallic layers supported on porous materials such as ceramics or stainless steel, have been considered due to their lower cost (thin Pd layer) and higher mechanical resistant (porous support) compared to dense Pd-based membranes [2,3]. Moreover, the use of Pd-alloys, in particular, Ag, Au, Pt, has grown in the recent years given their ability to resist sulfur poisoning in addition to their enhanced hydrogen permeability [4]. Therefore, the aim of this study was to fabricate a Pd-Au membranes supported on porous stainless steel (PSS) with the intent to produce high-purity hydrogen from natural gas steam reforming. The membrane used in this study was fabricated via an electroless plating technique for depositing Pd and electro-plating for the deposition of Au.

The initial characterization of the membrane by way of ideal selectivity took place at 400 °C with H₂, He and N₂, and with DP in the range of 1.5 - 3.0 bar. After ideal selectivity characterization of the Pd-Au/PSS membrane, the natural gas steam reforming reaction was carried out and the MR performance in terms of CH₄ conversion, hydrogen production and hydrogen permeate purity has been analyzed and will be discussed.

References

[1] Rostrup-Nielsen, J.R., Catalytic steam reforming. 1984: Springer.

[2] 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 membranes for hydrogen separation", Membranes, 4 (2014) 143-162.

[3] B. Anzelmo, J. Wilcox, S. Liguori, "Natural gas steam reforming reaction at low temperature and pressure conditions for hydrogen production via Pd/PSS membrane reactor", Journal of Membrane Science, 522 (2017) 343-350.

[4] Chen, C.-H. and Y.H. Ma, "The effect of H₂S on the performance of Pd and Pd/Au composite membrane". Journal of Membrane Science, 362 (2010) 535-544.