Small Cobalt Nanoparticles Favor Reverse Water-Gas Shift Reaction over Methanation Under CO2 Hydrogenation Conditions

21 September 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Cobalt-based catalysts are well-known to convert syngas into a variety of Fischer-Tropsch (FTS) products depending on the various reaction parameters, in particular particle size. In contrast, the reactivity of these particles has been much less investigated in the context of CO2 hydrogenation. In that context, surface organometallic chemistry (SOMC) was employed to synthesize highly dispersed cobalt nanoparticles (Co-NPs) with particle size ranging from 1.6 to 3.0 nm. These SOMC-derived Co-NPs display significantly different catalytic performances under CO2 hydrogenation conditions: while the smallest cobalt nanoparticles (1.6 nm) catalyze mainly the reverse water-gas shift reaction, the larger nanoparticles (2.1-3.0 nm) favor the expected methanation activity. Operando X-ray absorption spectroscopy shows that the smaller cobalt particles are fully oxidized under CO2 hydrogenation conditions, while the larger ones remain mostly metallic, paralleling the observed difference of catalytic performances. This fundamental shift of selectivity, away from methanation to reverse water-gas shift (rWGS) for the smaller nanoparticles is noteworthy and correlates with the formation of CoO under CO2 hydrogenation conditions.


CO2 Hydrogenation
Catalyst Design
Particle Size Effect
Operando XAS

Supplementary materials

Supporting Information: Small Cobalt Nanoparticles Favor Reverse Water-Gas Shift Re-action over Methanation Under CO2 Hydrogenation Conditions
Experimental section, characterization of materi-als, XAS data, CO2 hydrogenation data


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