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The role of Pt-FexOy interfacial sites for CO oxidation

Ro, Insoo, Aragao, Isaias B., Chada, Joseph P., Liu, Yifei, Rivera-Dones, Keishla R., Ball, Madelyn R., Zanchet, Daniela, Dumesic, James A., Huber, George W.
Journal of catalysis 2018 v.358 pp. 19-26
X-ray photoelectron spectroscopy, adsorption, atmospheric pressure, carbon monoxide, catalysts, energy, hydrogen, iron, iron oxides, oxidation, oxygen
Supported Pt catalysts with different Fe/Pt atomic ratios were synthesized using controlled surface reactions to deposit (cyclohexadiene) iron tricarbonyl onto Pt/SiO2 to create Pt-FexOy interfacial sites. X-ray photoelectron spectroscopy measurements show that Pt and Fe species exist as metallic Pt and Fe oxides phases, respectively, after treatment in H2 at 573 K, whereas Fe becomes more oxidized under reaction conditions for CO oxidation at 313 K (CO:O2 = 1:1). The addition of Fe increases the turnover frequency of Pt1Fex/SiO2 at 313 K and atmospheric pressure by up to two orders of magnitude compared to Pt/SiO2. The reaction order with respect to the O2 partial pressure suggests that O2 adsorption on the surface is likely to be a rate controlling step for both Pt/SiO2 and Pt1Fe0.2/SiO2. The enhanced activity over Pt1Fex/SiO2 catalysts compared to Pt/SiO2 can be associated with a lower energy barrier for O2 adsorption and activation over Pt-FexOy interfacial sites.