An unconventional Au/TiO2 PROX system for complete removal of CO from non-reformate hydrogen

Au-based catalysts, generally known for high activity in the selective catalytic oxidation of CO to CO2 at ambient temperatures, can play a significant role in increasing the fuel cell system’s CO tolerance. In this work, an unconventional CO tolerance method, using an Au/TiO2 “guard bed”, has been investigated. The system is unconventional in the sense that it does operate as a PROX catalyst, but not in a traditional reformer system configuration. Instead, it has been developed to completely remove CO onboard the vehicle over a wide range, ppm to percentage levels, from impure pressurized H2-rich gas, i.e. from partially enriched H2 that would be stored in a fuel tank/cylinder but that would have some CO contamination and would essentially be dry. This set up will allow a reduction in the cost and complexity of conventional “off-board” hydrogen enrichment. The system CO tolerance obtained with the Au/TiO2 system was compared with state of the art PtRu/C and PtMo/C CO tolerant anode technologies. Catalytic effectiveness in the removal of CO has been directly monitored by both direct analytical measurements and by monitoring the operation of a laboratory fuel cell to which the purified hydrogen stream was passed.