Yang Lou1 Jingyue Liu1

1, Arizona State University, Tempe, Arizona, United States

Preferential oxidation of CO (CO-PROX) in H2-rich stream has been recognized critical to efficiently eliminating the CO molecules to purify hydrogen [1-2]. However, the major challenge for CO-PROX is the low activity at low temperatures and dramatic drop of activity at high temperatures. Although the introduction of Fe species to Pt-based catalysts is able to simultaneously enhance the oxygen activation and weaken the CO adsorption strength these catalysts cannot completely convert CO to CO2 with excellent O2 selectivity (O2 selectivity ≥ 50%) under a wide temperature window ranging from room temperature to 200 oC (the operation temperature of a low-temperature shift reactor). In this work, we report a new strategy to synthesize a single molecule catalyst by dispersing single-atom Fe species onto the surfaces of Pt nanoparticles and clusters that are supported on high-surface-area alumina. Such a catalyst is used for oxidation of CO in the excess of H2 (CO-PROX). The synthesized Fe1/Pt/Al2O3 can achieve 100% CO conversion and 50% O2 selectivity with a reaction temperature window ranging from 25 oC to 200 oC (O2/CO molecular ratio of 1) and 100% CO conversion and 100% O2 selectivity from 25 oC to 140 oC (stoichiometric O2/CO ratio). Moreover, the Pt specific rate of the Fe1/Pt/Al2O3 catalyst is more than 3 times higher than that of the previous best Pt-based catalysts. The structural and electronic stability of single-atom Fe species under reaction conditions and the possible structural model of the Fe1/Pt systems will be discussed [3].

[1] Qiao, B., Liu, J., Wang, Y.-G., Lin, Q., Liu, X., Wang, A., Li, J., Zhang, T. Liu, J. ACS Catal. 2015, 5, 6249-6254.
[2] Liu, K., Wang, A. Q., Zhang, T. ACS Catal. 2012, 2, 1165-1178.
[3] This work was supported by National Science Foundation under CHE-1465057.