Hydrogen production capacity of membrane reformer for methane steam reforming near practical working conditions

Currently, H-2 production techniques for application to proton exchange membrane fuel cells (PEMFC) are intensively investigated, aiming to realize a clean hydrogen society. Due to the limitation by the thermodynamics of methane steam reforming (MSR), multi-reactions and multi-steps should be performed before the generated H-2-rich gas could be delivered to PEMFC, which inevitably increases the cost of H-2. However, using a thermodynamic shifting membrane reformer, H-2 could be produced compactly from MSR, provided that the catalyst showed high performance for MSR reaction and membrane efficiently removed H-2 from the reaction zone. We presented here a Pd-based membrane reformer for MSR reaction. In contrast with previous reports, nickel-based catalyst pre-reduced at high temperature was applied in this work, as well as high performance Pd-based membrane. The performances of the membrane reformer in terms of H-2 production capacity were also widely investigated. It was found that combination of an active catalyst for MSR and a H-2 ultra-permeable Pd membrane obtained high flux of H-2 across the membrane and recovery rate of H-2 in the membrane reformer. For instance, 98.8% methane conversion, over 97.0% selectivity to CO2 and over 95.0% recovery rate of H-2 were obtained under mild working conditions. Simultaneously, the hydrogen flux across the membrane reached 18.6 m(3)/(m(2) h), and Pd-based pure H2 production capacity significantly increased and reached around 387.5 m(3)/(kg(Pd) h) in membrane reformer. Further work on stability investigation may develop an efficient on-site route of H-2 production process for application to on-site power generation using PEMFC. (C) 2008 Elsevier B.V. All rights reserved.