Effects of Zr Doping into Ceria for the Dry Reforming of Methane over Ni/CeZrO₂ Catalysts: In Situ Studies with XRD, XAFS, and AP-XPS

Journal Article · Mon Jan 06 00:00:00 EST 2020 · ACS Catalysis

DOI:https://doi.org/10.1021/acscatal.9b04451· OSTI ID:1603284

Zhang, Feng ^[1]; Liu, Zongyuan ^[2]; Chen, Xiaobo ^[3]; Rui, Ning ^[2]; Betancourt, Luis E. ^[2]; Lin, Lili ^[2]; Xu, Wenqian ^[4]; Sun, Cheng-jun ^[4]; Abeykoon, A. M. Milinda ^[5]; Rodriguez, José A. ^[6]; Teržan, Janvit ^[7]; Lorber, Kristijan ^[7]; Djinović, Petar ^[7]; Senanayake, Sanjaya D. ^[2]

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1. Stony Brook Univ., NY (United States)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)
3. State Univ. of New York (SUNY), Binghamton, NY (United States)
4. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
5. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
6. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States)
7. National Inst. of Chemistry, Ljubljana (Slovenia). Dept. of Inorganic Chemistry and Technology

The methane activation and methane dry reforming reactions were studied and compared over 4 wt % Ni/CeO₂ and 4 wt % Ni/CeZrO₂ (containing 20 wt % Zr) catalysts. Upon the incorporation of Zr into the ceria support, the catalyst exhibited a significantly improved activity and H₂ selectivity. To understand the effects of the Zr dopant on Ni and CeO₂ during the dry reforming of methane (DRM) reaction and to probe the structure–reactivity relationship underlying the enhanced catalytic performance of the mixed-oxide system, in situ time-resolved X-ray diffraction (TR-XRD), X-ray absorption fine structure (XAFS), and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) were employed to characterize the catalysts under reaction conditions. TR-XRD and AP-XPS indicate that ceria–zirconia supported Ni (Ni/CeZrO₂) is of higher reducibility than the pure ceria supported Ni (Ni/CeO₂) upon the reaction with pure CH₄ or for the methane dry reforming reaction. The active state of Ni/CeZrO₂ under optimum DRM conditions (700 °C) was identified as Ni⁰, Ce³⁺/Ce⁴⁺, and Zr⁴⁺. The particle size of both nickel and the ceria support under reaction conditions was analyzed by Rietveld refinement and extended XAFS fitting. Zr in the ceria support prevents particle sintering and maintains small particle sizes for both metallic nickel and the partially reduced ceria support under reaction conditions through a stronger metal–support interaction. Additionally, Zr prevents Ni migration from the surface into ceria forming a Ce_1–xNi_xO_2–y solid solution, which is seen in Ni/CeO₂, thus helping to preserve the active Ni0 on the Ni/CeZrO₂ surface.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: Slovenian Research Agency (ARRS); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
• Grant/Contract Number: AC02-06CH11357; SC0012704
• OSTI ID: 1603284
• Alternate ID(s): OSTI ID: 1631970
• Report Number(s): BNL--213666-2020-JAAM
• Journal Information: ACS Catalysis, Journal Name: ACS Catalysis Journal Issue: 5 Vol. 10; ISSN 2155-5435
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AP-XPS
CeZrO2 solid solution
CeZrO2 solid solution
XAFS
XRD
ceria
dry reforming of methane
nickel
zirconia