Small Cobalt Nanoparticles Favor Reverse Water‐Gas Shift Reaction Over Methanation Under CO2 Hydrogenation Conditions

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 t...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2023-12, Vol.62 (52), p.e202314274-n/a
Main Authors: Zhou, Xiaoyu, Price, Gregory A., Sunley, Glenn J., Copéret, Christophe
Format: Article
Language:English
Subjects:
Absorption spectroscopy
Carbon dioxide
Catalysts
CO2 Hydrogenation
Cobalt
Context
Heterogeneous Catalysis
Hydrogenation
Methanation
Nanoparticles
Operando Spectroscopy
Organometallic compounds
Particle size
Particle Size Effect
Shift reaction
Synthesis gas
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Summary: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 sizes 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 (rWGS) 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 for the smaller nanoparticles is noteworthy and correlates with the formation of CoO under CO2 hydrogenation conditions. Small cobalt nanoparticles readily oxidize under CO2 hydrogenation conditions according to X‐ray absorption spectroscopy, favoring reverse water‐gas shift reaction, in contrast to larger particles that remain metallic and catalyze methanation.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202314274