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

Abstract

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 CO 2 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 H 2 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.