Effect of steam content on nickel nano-particle sintering and methane reforming activity of Ni-CZO anode cermets for internal reforming SOFCs
- Effect of steam content on nickel nano-particle sintering and methane reforming activity of Ni-CZO anode cermets for internal reforming SOFCs
- 다사리하리; 박선영; 지호일; 김혜령; 손지원; 김병국; 이해원; 이종호
- SOFC; Catalyst deactivation; Ni-CZO cermet anodes; Nickel nano-particle sintering; Methane steam reforming activity
- Issue Date
- Applied catalysis A, General
- VOL 411-412, 160-169
- In this work, the reforming activity of Ni–Ce0.75Zr0.25O2 (Ni–CZO) solid oxide fuel cell (SOFC) cermet
anodes for steam reforming of methane has been investigated in the absence of electrochemical effects
and the results were compared with Ni–Ce0.9Gd0.1O2 (Ni–CGO) cermet anodes. From X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy/energy dispersive X-ray
spectroscopy (TEM/EDS) and CHN analysis on the spent Ni–CZO anode cermets, it was found that a
decrease in reforming activity at higher steam-to-carbon ratios (S/C) was due to sintering of nickel
nano-particles rather than re-oxidation or sintering of bulk nickel and carbon formation. Time-on-stream
analysis demonstrated a higher reforming activity for Ni–CZO cermet anodes compared to Ni–CGO cermet
anodes. While the initial sizes of nickel nano-particles were similar (5–10 nm) for both cermet anodes,
after the operation under steam-rich conditions (S/C - 1.5) the nickel nano-particles on Ni–CGO were
found to be significantly larger (20–40 nm) than those on Ni–CZO (15–25 nm). Under steam-lean conditions
(S/C - 0.5), the size of nickel nano-particles remained below 10 nm for both cermet anodes during
the operations, indicating that the effect of sintering of Ni nano-particles on the performance was negligible.
The reforming activity is still higher for Ni–CZO cermet anodes than Ni–CGO cermet anodes, which
could be attributed to higher concentration of ex-solved nickel nano-particles as well as lower Ce4+/Ce3+
reduction energy of CZO than CGO support.
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