Sean C. Emerson

Advanced Water-Gas Shift Membrane Reactor

The overall objectives for this project were: (1) to identify a suitable PdCu tri-metallic alloy membrane with high stability and commercially relevant hydrogen permeation in the presence of trace amounts of carbon monoxide and sulfur; and (2) to identify and synthesize a water gas shift catalyst with a high operating life that is sulfur and chlorine tolerant at low concentrations of these impurities. This work successfully achieved the first project objective to identify a suitable PdCu tri-metallic alloy membrane composition, Pd{sub 0.47}Cu{sub 0.52}G5{sub 0.01}, that was selected based on atomistic and thermodynamic modeling alone. The second objective was partially successful in that catalysts were identified and evaluated that can withstand sulfur in high concentrations and at high pressures, but a long operating life was not achieved at the end of the project. From the limited durability testing it appears that the best catalyst, Pt-Re/Ce{sub 0.333}Zr{sub 0.333}E4{sub 0.333}O{sub 2}, is unable to maintain a long operating life at space velocities of 200,000 h{sup -1}. The reasons for the low durability do not appear to be related to the high concentrations of H{sub 2}S, but rather due to the high operating pressure and the influence the pressure has on the WGS reaction at this space velocity.

Model-Based Design of Energy Efficient Palladium Membrane Water Gas Shift Fuel Processors for PEM Fuel Cell Power Plants

An integrated, palladium alloy membrane Water-Gas Shift (WGS) reactor can significantly reduce the size, cost and complexity of a fuel processor for a Polymer Electrolyte Membrane fuel cell power system. Physics-based system modeling that accounts for component performance under transient conditions is essential to derive the full benefit from this technology. Modeling elucidates system designs and operating philosophies that maximize system efficiency and performance. This advanced WGS membrane reactor fuel processor is enabled by high activity noble metal alloy/ceria-based WGS catalysts [1, 2] and porous metal tube supported palladium alloy membranes such as those investigated by Ma and co-workers [3–6].