Impact of small promoter amounts on coke structure in dry reforming of methane over Ni/ZrO2. Issue 12 (28th May 2020)

• Record Type: Journal Article
• Authors: Franz, Robert; Kühlewind, Tobias; Shterk, Genrikh; Abou-Hamad, Edy; Parastaev, Alexander; Uslamin, Evgeny; Hensen, Emiel J. M.; Kapteijn, Freek; Gascon, Jorge; Pidko, Evgeny A.
• Is Part Of: Catalysis science & technology. Volume 10:Issue 12(2020)
• Page Start: 3965
• Page End: 3974
• Publication Date: 2020-05-28
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d0cy00817f
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Choosing the correct alkali metal as a promoter not only reduces coke formation in dry reforming of methane but also removes coke via gasification. Abstract : 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/ZrO2 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/ZrO2 catalysts is attributed to the enhanced coke gasification via carbonate species on top of the site blocking effects.