Hydrocarbons can be converted into a H2- and CO-rich gas stream for a variety of applications, including fuel cells, through catalytic partial oxidation (CPOX). This process requires a catalyst with thermal and mechanical stability, as well as resistance to deactivation in the presence of common contaminants. Liquid fuels considered appropriate for transportation applications often contain sulfur and aromatic compounds that deactivate traditional supported metal catalysts through sulfur poisoning and carbon formation. Typically, precious metal catalysts like Rh have been found to be the most active and stable materials for the CPOX of these fuels. However, these catalysts are very expensive.  Previous work has demonstrated that substituting active metals into thermally stable oxide structures, such as pyrochlores, significantly reduces catalyst deactivation from sintering, sulfur poisoning, and excessive carbon formation. Further, the potential for reducing the amount of expensive, precious metal required to achieve desired levels of catalyst performance has been demonstrated by placing less expensive metals (Ni and Ru) in sections of the reactor that are less likely to cause deactivation. This is a result of the indirect mechanism widely reported in literature for the CPOX of hydrocarbons.  This work demonstrates the potential benefit of a multi-composition, or �graded,� monolith comprised of Ni-, Ru-, and Rh-substituted pyrochlore catalysts deposited onto alumina foams and placed in different configurations in the reactor. Catalytic testing followed by carbon characterization of the individual coated foams allowed for quantification of carbon formation on each catalyst in different sections of the reactor during CPOX.

Carbon formation in a graded-composition monolithic catalyst during partial oxidation of hydrocarbons

243rd National Meeting (2012)

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