Dry reforming of methane (DRM) is attractive for producing value-added syngas by consuming the CH₄ and CO₂ greenhouse gases, but the catalysts are challenged by sintering and coking. A series of NiCo/CeO₂-Al₂O₃ catalysts with the nominal composition of (Ni_0.5Co_0.5)Al_xCe_10-xO_y (x = 0–10) were prepared by sol–gel method. This work demonstrates that the formation of (NiCo)Al_xO_y spinel (or spinel-like) phase enhanced the metal-support interaction (MSI) and plays a crucial role in the catalyst’s performance. Small (NiCo)Al_xO_y grains reside in the holes and along the grain boundaries of the CeO₂ matrix in the fresh catalysts. (NiCo)Al_xO_y becomes amorphous under DRM conditions and exhibits a high affinity to both NiCo NPs and the CeO₂ grains, keeping the MSI strong enough to direct the sintering of metal NPs to the Ostwald ripening pathway. We proposed that the sintering of NiCo NPs in the x ≥ 2 catalysts follows the Ostwald ripening pathway: (NiCo)Al_xO_y serves as the diffusion path for the metal atoms while CeO₂ serves as the spacer shaping the length and cross-section of the diffusion path. A proper Al₂O₃/CeO₂ ratio makes the inter-grain diffusion path long and narrow, which effectively hinders the sintering of NiCo NPs. The NiCo/CAO-2 catalyst with the stoichiometric Ni_0.5Co_0.5Al₂O₄ spinel composition exhibits the best DRM performance. The CH₄ and CO₂ conversions at 700 ℃ achieved 76 % and 84 %, respectively. The catalyst was stable during the 100-hour DRM test, and the carbon deposition rate was small. The present work provides a new strategy for developing anti-sintering catalysts for high-temperature reactions.

中文翻译：

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通过塑造 Ostwald 成熟扩散路径提高 NiCo/CeO2-Al2O3 催化剂在甲烷干重整中的烧结稳定性


甲烷干重整 （DRM） 对于通过消耗 CH₄ 和 CO₂ 温室气体生产增值合成气很有吸引力，但催化剂受到烧结和焦化的挑战。通过溶胶-凝胶法制备了一系列标称组成为 （Ni_0.5Co_0.5）Al_xCe_10-xO_y （x = 0–10） 的 NiCo/CeO_{2-Al 2}O₃ 催化剂。这项工作表明，（NiCo）Al_xO_y 尖晶石（或类似尖晶石）相的形成增强了金属-载体相互作用 （MSI），并在催化剂的性能中起着至关重要的作用。小 （NiCo）Al_xO_y 晶粒位于新催化剂中 CeO₂ 基体的空穴中和沿晶界。（镍钴）Al_xO_y 在 DRM 条件下变为无定形，并且对 NiCo NPs 和 CeO₂ 晶粒都表现出高亲和力，使 MSI 足够强，以将金属 NPs 的烧结引导到 Ostwald 成熟途径。我们提出 NiCo NPs 在 x ≥ 2 催化剂中的烧结遵循 Ostwald 成熟途径：（NiCo）Al_xO_y 作为金属原子的扩散路径，而 CeO₂ 作为形成扩散路径长度和横截面的间隔物。适当的 Al₂O₃/CeO₂ 比例使晶间扩散路径长而窄，从而有效地阻碍了 NiCo NPs 的烧结。具有化学计量 Ni_0.5Co_0.5Al₂O₄ 尖晶石成分的 NiCo/CAO-2 催化剂表现出最佳的 DRM 性能。在 700 °C 下，CH₄ 和 CO₂ 的转化率分别达到 76% 和 84%。 催化剂在 100 h DRM 测试期间稳定，积碳速率小。本研究为开发高温反应用抗烧结催化剂提供了一种新策略。