469620 Understanding the Role of Fe in Bi-Metallic Ni-Fe Dry Reforming Catalysts: A Combined in-Situ XAS-XRD Study

Thursday, November 17, 2016: 9:24 AM
Franciscan C (Hilton San Francisco Union Square)
Sung Min Kim1, Paula Abdala1, Wouter van Beek2, Tigran Margossian3, Christophe Copéret3, Christoph Mueller1 and Qasim Imtiaz4, (1)Department of Mechanical and Process Engineering, ETH, Zürich, Switzerland, (2)ESRF, Grenoble, France, (3)Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland, (4)Department of Mechanical and Process Engineering, ETH Zürich, Zürich, Switzerland

One major drawback of Ni-based dry reforming (CH4 + CO2 → 2CO + 2H2) catalysts is coke formation.1,2 In order to overcome this limitation, bi-metallic Ni-Fe catalysts have been developed, synthesized via a hydrotalcite-based precursor. Here, Ni and Fe are embedded in a thermally stable MgxAlyOz matrix. The formation of alloyed Ni-Fe nanoparticles was confirmed via TEM-EDX, XRD and XAS measurements. The catalytic performance of monometallic Ni and Fe as well as the Ni-Fe bimetallic catalysts was evaluated at 650 °C. It was found that the bi-metallic catalysts, in particular, Ni4Fe1 (2.6 h-1 of TOFCH4) have a high activity and stability, whereas fast deactivation and a low catalytic activity was observed for monometallic Ni (1.8 h-1 of TOFCH4) and Fe (0.4 h-1 of TOFCH4) catalysts, respectively. In-situ XAS and XRD analysis in combination with Raman, TEM, TGA and TPO allowed us to elucidate the underlying reason for the high activity and stability of the bimetallic Ni-Fe catalyst. The formation of FeO was observed in bimetallic Ni-Fe catalysts via in-situ XAS measurement, whereas metallic Ni0 was maintained in both Ni and Ni-Fe catalysts. Furthermore, using combined in-situ XAS and XRD experiments, we could demonstrate that FeO removes the carbon deposited via a redox mechanism (C + FeO → CO + Fe).

References

  1. V.C.H. Kroll, H.M. Swaan, S. Lacombe, C. Mirodatos, J. Catal.,1996, 2, 387-398
  2. E. Ruckenstein and Y.H. Hu, J. Catal.,1996, 2, 230-238
  3. S. A. Theofanidis, V. V. Galvita, H. Poelman, G. B. Marin, ACS Catal., 2015, 5, 3028-3039.

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See more of this Session: Catalysis for C1 Chemistry IV: CH4 Conversion II
See more of this Group/Topical: Catalysis and Reaction Engineering Division