545388 Low Temperature Steam Reforming of Methane over Pd-Zn Alloy Catalysts in an Electric Field

Monday, June 3, 2019: 5:36 PM
Texas Ballroom D (Grand Hyatt San Antonio)
Maki Torimoto1, Danny Harjowinoto1, Shuhei Ogo1, Shinya Furukawa2, Takuma Higo1, Tomohiro Yabe1 and Yasushi Sekine1, (1)Applied Chem., Waseda Univ., Tokyo, Japan, (2)Hokkaido Univ., Sapporo, Japan

In recent years, world-wide demand for H2 has been increasing because of its potential for alternative energy source. While steam reforming of methane (SR) is the most common process for H2 production, it requires high temperature and pressure to dissociate the strong C-H bond of methane. Therefore, a new process that can be operated under milder condition is desired. Steam reforming of methane in an electric field (Electreforming: ER) proceeds at low temperature at which conventional catalytic reaction (SR) hardly proceeds. Our previous works revealed that reaction mechanism for ER was different from that for SR, and surface protonics induced by the electric field plays key role to promote reaction at low temperature. However, the role of supported metals on ER activity has not been investigated. In this study, to elucidate effects of supported metals on ER activity, we prepared Pd-Zn alloy catalysts supported on Ce0.5Zr0.5O2 (CZO) and performed activity tests with or without an electric field. The prepared catalysts were also characterized by X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), and Infrared spectroscopy (IR). From activity tests over Pd/CZO and Zn/CZO, it is considered that Pd is the active site for both ER and SR because Zn/CZO showed almost no activity with or without an electric field. Therefore, we evaluated activity of Pd-Zn alloy catalysts by calculating TOF per Pd atom. As the Zn amount increased, TOF for ER increased while TOF for SR decreased. XAFS and IR measurements revealed that adjacent Pd sites decreased with increased the Zn content and the electric density of Pd over Pd-Zn/CZO increased by the electron transfer from Zn to Pd. From these results, it is considered that increasing the electron density of Pd atom by the alloying with Zn contributes to the high ER activity of Pd-Zn/CZO catalysts.

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