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

In this work, electroless deposition was used to fabricate a 5.0 mu m thick Pd-28Au (wt. %) membrane (16.10 cm(2)) 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 degrees C and 580 degrees 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. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.