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Low-temperature CO oxidation over Pt-Fe/SiO2 and Pt/ɣ-Fe2O3 catalysts

  • Mengqiao Di (Chalmers University of Technology, Sweden)
Date
Tuesday 31 March 2020
Time
Address
Hotel NH Noordwijk Conference Centre Leeuwenhorst

Mengqiao Dia, Magnus Skoglundha and Per-Anders Carlssona
a Department of Chemistry and Chemical Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
e-mail: mengqiao@chalmers.se

Figure 1: TEM of synthesized Pt48Fe52 alloyed nanoparticles (right) and STEM of synthesized Pt/ɣ-Fe2O3 (left). The large bright part is from overlapping of ɣ-Fe2O3.

The catalytic oxidation of CO over supported bimetallic catalysts, sometimes showing strong metal-support interactions, has been widely studied for decades. This is because of the many relevant applications, e.g., suppressing CO poisoning of anode reactions in polymer electrolyte membrane fuel cells and mitigation of CO emissions from vehicles, especially the cold-start emissions during the start-up of the vehicle. Still, the low-temperature performance of most catalysts is insufficient due to detrimental CO self-poisoning of the catalytic reaction. It has been shown that the catalytic activity of platinum (Pt) nanoparticles can be enhanced by the choice of the support material, e.g., CeO2, FexOy or NiO [1] -exhibiting redox properties , or by adding a promoters such as iron (Fe), tin (Sn) or copper (Cu) [2] .
    
In this work, alloyed Pt-Fe nanoparticles and Pt nanoparticles supported on maghemite (ɣ-Fe2O3) were synthesized by wet-chemical methods, see Figure [1]. Synthesis of nanosized ɣ-Fe2O3 was explored by screening various methods for drying and calcination. A number of ex situ methods (BET, XRD and TEM/EDX) were employed to characterize the surface area, crystal structure and morphology of the parent samples. Incipient wetness impregnation (IWI) was employed to load Pt onto ɣ-Fe2O3 as to obtain the platinum nanoparticles dispersed over the nanosized ɣ-Fe2O3  support. Moreover, alloyed Pt-Fe nanoparticles were produced and deposited onto silica, and the samples were characterized by XRD, TEM/EDX and TGA/DSC.

Currently we study the performance of the catalysts, using Pt/SiO2 as reference, by operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The main focus is on understanding how the different catalyst formulations counteracts CO self-poisoning and to which degree this still influences their catalytic activity. Also, we study how different pre-treatment conditions (reducing/oxidizing/annealing) may play a role for the low-temperature activity.

Acknowledgements

The Competence Centre for Catalysis is hosted by Chalmers University of Technology and financially supported by the Swedish Energy Agency and the member companies AB Volvo, ECAPS AB, Johnson Matthey AB, Preem AB, Scania CV AB, Umicore AG & Co. KG and Volvo Car Corporation AB.

References

  1. Liu, L., Zhou, F., Wang, L., Qi, X., Shi, F., & Deng, Y. (2010). Low-temperature CO oxidation over supported Pt, Pd catalysts: Particular role of FeOx support for oxygen supply during reactions. Journal of Catalysis, 274(1), 1-10..
  2. Siani, A., Alexeev, O. S., Captain, B., Lafaye, G., Marécot, P., Adams, R. D., & Amiridis, M. D. (2008). Synthesis of cluster-derived PtFe/SiO2 catalysts for the oxidation of CO. Journal of catalysis, 255(2), 162-179.
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