Steam methane reforming in a PdAu membrane reactor: Long-term assessment

• Pd28Au/YSZ/PSS membrane was integrated with catalytic SMR reactor to produce H2.
• Methane conversion of 84% versus equilibrium of 35%.
• H2 flux and methane conversion stable at 2.8 MPa for 500 h.
• H2 permeate purity >99.2% over the course of testing.
• Membrane was completely annealed as revealed by EDS, XRD, XRF and ICP-AES.

In this work, electroless deposition was used to fabricate a 5.0 μm thick Pd28Au (wt. %) membrane (16.10 cm2) supported on a YSZ/PSS substrate. After annealing in hydrogen, steam methane reforming (SMR) was conducted continuously for 530 h, with permeate purity remaining above 99.2% for the duration. The reactor used a 0.5 wt. % Ru/Al2O2 catalyst and ran at 2.8 MPa and a steam-to-carbon ratio of 3, with temperature varied between 480 °C and 580 °C. Methane conversion was as high as 94% depending on temperature and space velocity. This represents a significant improvement over the thermodynamic equilibrium shift of 35% under similar conditions. Additionally, the hydrogen flux and overall methane conversion showed stable performance over time. The membrane thickness and composition were verified using SEM/EDS, XRD, XRF and ICP-AES. Furthermore, cross sectional EDS and XRD data indicated uniform gold composition throughout the film, suggesting homogeneous alloy formation.