(682a) Tuning the Local Coordination Environment of Ni in Ni/CeO2 Catalyst for More Efficient Dry Reforming of Methane

Dry reforming of methane (DRM) has gained significant interest for its ability to convert two major greenhouse gases, CH₄ and CO₂, into syngas [1]. Nickel-based catalysts are highly active for DRM, but they are highly susceptible to sintering and carbon deposition [2]. Consequently, extensive research has been directed towards enhancing their stability against sintering and preventing the formation of carbonaceous deposits. As a support, CeO₂ is known to enhance the nickel dispersion, which in turn improves the resistance of catalyst against sintering and coke formation. We herein successfully developed Ni/CeO₂ catalysts with different Ni local coordination environments (Ni/CeO₂ and Ni/CeO₂_OH) by using two different CeO₂ supports. The experimental results showed that the Ni/CeO₂_OH catalyst exhibited considerably higher activity and stability in the DRM reaction comparing to Ni/CeO₂ (Figure 1a). CH₄ conversion declined 26% on Ni/CeO₂_OH after 12 hrs on-stream, while reduced up to 41% on Ni/CeO₂ (Figure 1b). It was found that more coke species were present on spent Ni/CeO₂_OH than on spent Ni/CeO₂ despite the better activity and stability achieved on the former catalyst, evidencing that the catalytic deactivation was dominated by the sintering of Ni species rather than the coke deposition. This was confirmed by the results of EDS mapping of spent catalysts after 12 hrs of DRM (Figure 1c, 1d). It was observed that 5Ni/CeO₂_OH catalyst has a much smaller crystalline size of CeO_2, and larger surface area comparing to 5Ni/CeO₂, suggesting that the strong interaction between Ni and CeO₂ within Ni/CeO₂_OH catalyst significantly suppressed the sintering of Ni during DRM reaction.

References

[1] R.Y. Chein and W.Y. Fung, Int. J. Hydrog. Energy, 44: 14303-14315, 2019.

[2] A. Kambolis, H. Matralis, A. Trovarelli, and C. Papadopoulou, Appl. Catal. Gen., 377: 16-26, 2010.