Coke deposition is one of the main challenges in the commercialisation of dry reforming of methane over supported Ni catalysts. Besides the coke quantity, the structure of the deposits is also essential for the catalyst lifetime. Accordingly, in this study, we analysed the effect of Na, K, and Cs promoters on both these variables over Ni/ZrO(2)catalysts. Besides blocking the most active coke-forming sites already at low loading, the promoting effect of the alkali metals is also contributed to by their coke gasification activity. To evaluate the additional impact of the latter, the behaviour of alkali-doped catalysts was compared to that for Mn-doped catalysts, exclusively featuring the site-blocking promotion mechanism. While the conversion is barely affected by the type of promoter, it has a profound effect on the amount and the composition of carbon deposits formed during the reaction. Promoting with K or Mn reduces the coke content to a similar degree but with less carbon fibres observed in the case of K. The promotion by Cs and Na results in the lowest coke content. The superior performance of Cs and Na-doped Ni/ZrO(2)catalysts is attributed to the enhanced coke gasificationviacarbonate species on top of the site blocking effects.
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机译：可口可乐沉积的主要挑战之一甲烷干重整的商业化在支持镍催化剂。数量、结构的存款也催化剂寿命的必要条件。在这项研究中,我们分析了Na的影响,K,这两个变量在Cs推动者Ni / ZrO(2)催化剂。活跃coke-forming网站已经在低加载,碱金属的促进作用也导致焦炭气化活动。后者,alkali-doped的行为催化剂是Mn-doped相比专门的催化剂屏蔽网站推广机制。类型的转换几乎没有影响子,却有着深刻的影响和碳沉积形成的构成在反应。内容相似的程度,但减少了可乐用更少的碳纤维中观察到的情况k Cs和Na结果的推广可口可乐最低内容。Cs和Na-doped Ni / ZrO(2)是由于催化剂增强可乐gasificationviacarbonate物种上网站的屏蔽效果。
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