This work investigates the effect of Ni crystallite size and oxygen vacancies of the support on the formation of carbon over Ni/CeO₂ catalysts for dry reforming of methane at 1073 K. A large crystallite size variation is achieved by using different Ni loading (5 and 10 wt%) and calcination temperatures (673, 873, 1073 and 1473 K). In situ XRD and XANES experiments reveal that the increase in calcination temperature increases the Ni crystallite size, whereas the amount of oxygen vacancies decreases. The amount of carbon formed during DRM increases as Ni crystallite size increases, achieving a maximum at around 20−30 nm and then, it continuously decreases. However, carbon deposition is negligeable below 10 nm and above 100 nm. For the catalysts with very large Ni crystallite sizes, the CH₄ dissociation rate is likely so low that carbon species formed reacts and carbon accumulation does not take place. However, the oxygen vacancies of ceria do not contribute to the carbon removal from the Ni surface due to the low metal-support interface on these large Ni particles.

这项工作研究了载体的 Ni 微晶尺寸和氧空位对 Ni/CeO ₂催化剂上碳形成的影响，用于在 1073 K 下干式重整甲烷。通过使用不同的 Ni 负载量（5 和10 wt%）和煅烧温度（673、873、1073 和 1473 K）。就地XRD 和 XANES 实验表明，煅烧温度的增加会增加 Ni 微晶的尺寸，而氧空位的数量会减少。DRM 过程中形成的碳量随着 Ni 微晶尺寸的增加而增加，在 20-30 nm 附近达到最大值，然后不断减少。然而，碳沉积在 10 nm 以下和 100 nm 以上可以忽略不计。对于具有非常大的 Ni 微晶尺寸的催化剂，CH ₄离解速率可能非常低以致于形成的碳物质发生反应并且不会发生碳积累。然而，由于这些大 Ni 颗粒上的低金属-载体界面，二氧化铈的氧空位无助于从 Ni 表面去除碳。