(380e) Precious Metal Monolithic Catalysts for Fuel Processing – Overcoming the Limitations of Base Metal Particulate Catalysts
Fuel processing for small scale hydrogen production from hydrocarbons either for fuel cell applications or for industrial hydrogen use involves several unit operations and use of several catalysts. These are desulfurization of the hydrocarbon, steam reforming or autothermal reforming, water gas shift and final clean up by preferential oxidation of CO (PROX) or a PSA system. Identical unit operations can be found in large scale hydrogen plants and initial attempts were to scale down those plants for fuel cell applications and use the same traditional particulate base metal oxide catalysts. However, existing large scale hydrogen plants cannot simply be reduced in size to meet the economic, safety and duty cycle requirements for applications for fuel cells, fueling stations and industrial uses such as hydrogenation reactions, gas turbine cooling; metal processing etc. Specifically, we have found severe limitations of traditional catalysts for hydrogen production in the environment (i.e. no trained operator) and duty cycle (i.e. frequent start and stop) encountered during fuel cell applications. Especially start-stop operations can occur daily (i.e in Japan) and decrease the catalysts' mechanical integrity and lead to loss of catalytic activity due water condensation or low temperature steam or air exposure. We did extensive simulated start-stop testing of both base metal particulate and precious metal monolithic catalysts and concluded that precious metal monolithic catalysts are the best option to overcome the inherent limitation of base metal particulate catalysts in those applications. In addition to being resistant to daily start-stop operation (resistance to air and water or steam exposure) these catalysts enable a faster start-up because of their lower heat capacity, lower pressure drop of the overall reformer. Catalyst washcoats also enable the use of catalyzed heat exchangers and novel reactor concepts to minimize heat transfer resistances and significant size reduction of the entire reformer.