Preferential oxidation (PROX) of CO in H2-rich stream has received significant interest to provide clean H2 for proton exchange membrane fuel cell (PEMFC) operation. This is because the H2 produced via hydrocarbons reforming contains CO as a byproduct. CO is poisoning and can deactivate Pt catalysts used in the fuel cell electrodes. Thus, there is a need for selective removal of CO to reduce its concentration to ppm level before H2 is used. The key to the PROX research is to find good catalyst which can remove CO efficiently and selectively. There have been considerable research efforts in the field, with various types of developed catalysts. However, one common problem with current catalysts is their narrow operation temperature window, with a rapid decrease in the PROX selectivity above around room temperature. Because PROX typically occurs between around RT and 180 °C for practical applications, it is thus of high desire to achieve good control on the activity and selectivity properties in a broader temperature range. We report the study of Pt-M (M=Mn and Ni) alloy nanoparticles with engineered surfaces consisting of bifunctional active sites in CO PROX, and our finding that the activity and selectivity properties can be correlated to reducibility of the second element as well as the surface geometry. The findings led to the development of new catalysts possessing better PROX properties, with Pt-Mn alloy nanoparticles showing 100% PROX selectivity up to about 170 °C and octahedral Pt3Ni showing both high activity and 100 % selectivity up to about 100 °C. We believe the research provides valuable guidance in new catalyst development to achieve tunable PROX properties via engineering the catalyst active sites.

Tuning carbon monoxide preferential oxidation properties on platinum alloy nanoparticle catalyst via engineering the active sites

253rd National Meeting (2017)

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