free reformate to the fuel cell. Under different operating parameters, the same fuel processor operated up to a <¡1 of 3.8 without carbon formation. During operation at this condition, there were some C-2 hydrocarbons in the reformate stream.

CO Clean-up Technologies

Proton Exchange Membrane (PEM) anode catalysts are poisoned by carbon monoxide. TheLTS converter in the ADL multi-fuel reformer is designed to achieve equilibrium concentrations of CO according to the equilibrium constant of the water-gas shift reaction. In practice, the CO concentration is reduced by the LTS to a range between 0.5 to 1.0% depending on the steam to carbon ratio and the bed operating temperature. However, depending on the PEM fuel cell anode catalyst composition and loading, significant performance degradation can occur at CO concentrations on the order of 10 to 100 ppm. Therefore, some sort of CO polishing device is needed between the fuel processor and the fuel cell. In support of the gasoline reformer program, ADL is working with Los Alamos National Lab (LANL) in order to integrate a LANL preferential oxidizer (PROX) into the reformer system Along with this effort, ADL is also working with Johnson Matthey to integrate their proprietary PROX technology with the gasoline reformer. Finally, ADL is currently testing a proprietary PROX catalyst which features enhanced selectivity over normal platinum based PROX catalysts. This catalyst was tested in a temperature range between 150-270 °C with simulated reformate and has shown CO oxidation rates comparable to conventional PROX catalysts with significantly enhanced selectivity. As another approach to CO clean-up, ADL is also investigating the use of membrane technology to supply pure hydrogen to the fuel cell.

1—'—I—1—I—'—r 1.60 2.00 2.40 2.80 320 3.60

Equivalence Ratio Figure 8. JP-8 POX Conversion

1—'—I—1—I—'—r 1.60 2.00 2.40 2.80 320 3.60

Equivalence Ratio Figure 8. JP-8 POX Conversion


Five years of development effort at Arthur D. Little have resulted in a family of low-cost, small-scale fuel processor designs which have been optimized for multiple fuels, applications, and fuel cell technologies. When properly integrated, system efficiencies of 43% at rated power can be achieved as shown in Table 1, which are similar to reported system efficiencies using methanol steam reformers. Other achievements to date include:

• 2500 + hours of operating experience at 50 kWe on ethanol, gasoline, JP-8, methanol, and natural gas

• Demonstrated performance of .7 kw/1 and .6 kW/kg compares favorably with PNGV targets.

• Simple, automotive-type control system developed.

• Difficult issues resolved with functioning hardware including:

• Vaporization of aromatics

• Catalyst thermal control

• Sulfur Control

• Promising paths for CO control including:

• Proprietary PROX catalyst with enhanced selectivity

• Membrane technology

Table 1. System Performance -E95

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