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Summary: CERIA-BASED WATER-GAS-SHIFT CATALYSTS
S. Swartz, A-M. Azad, M. Seabaugh
NexTech Materials, Ltd., Worthington, OH
Introduction
Proton-exchange membrane (PEM) fuel cells are being developed for automotive (motive and/or
auxiliary) and stationary (residential) power applications. PEM fuel cells operate either on pure
hydrogen or a hydrogen-rich gas with little or no carbon monoxide. In the near term, fuel cells will
need to be operated using our existing hydrocarbon fuel infrastructure (e.g., natural gas, propane,
gasoline or diesel). Fuel processors convert these hydrocarbons into a "clean" hydrogen fuel
needed for PEM fuel cell operation. The water-gas-shift (WGS) reaction (CO + H2 CO2 + H2O)
is a critical reaction used in fuel processors. This reaction increases the hydrogen content and
reduces the carbon monoxide concentration, prior to final CO "cleanup" in subsequent preferential
oxidation (or methanation) steps. Commercial WGS catalysts, designed for steady-state operation,
are unsuitable for fuel cell applications because of their tendency to degrade under transient (e.g.,
start-stop, load-following) conditions encountered real systems.
Over the past few years, NexTech Materials has pursued the development of WGS catalysts based
on ceria-supported precious metals. Our work has demonstrated that Pt/ceria catalysts offer several
advantages compared to existing copper-based catalysts: (1) operation over a wider range of
temperature (up to 400ºC); (2) no need for activation prior to use; (3) no degradation upon exposure
to air (non-pyrophoric); (4) capability for regeneration of deactivated catalysts by simple air-
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