These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
MS dopants DR Rev1 ChemRxiv.pdf (2.72 MB)
Impact of small promoter amounts on coke structure in dry reforming of methane over Ni/ ZrO2
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
revised on 20.05.2020 and posted on 21.05.2020by Robert Franz, Tobias Kuehlewind, Genrikh Shterk, Edy Abou-hamad, Alexander Parastaev, Evgeny Uslamin, Emiel J.M. Hensen, Freek Kapteijn, Jorge Gascon, Evgeny Pidko
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 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.