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O: Fachverband Oberflächenphysik

O 111: Heterogeneous Catalysis II

O 111.2: Talk

Friday, March 22, 2024, 10:45–11:00, TC 006

Ni-In Synergy in CO₂ Hydrogenation to Methanol Explained by Microkinetic Models — •Francesco Cannizzaro, Bart Klumpers, Ivo A. W. Filot, and Emiel J. M. Hensen — Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands

Highly dispersed Ni-In clusters can promote In₂O₃ catalysts for the hydrogenation of CO₂ to CH₃OH, a key reaction in the fight against global warming. However, fundamental understanding of the role of such clusters is lacking, hampering large-scale application of Ni-In₂O₃ catalysts. Herein, we employed density functional theory (DFT) and microkinetic modeling to study the influence of the composition of In₂O₃-supported Ni-In clusters on CO₂ hydrogenation. Lowest-energy Ni_nIn_8−n clusters (n = 0−7) were identified by combining genetic algorithms with an artificial neural network potential trained by DFT. At higher Ni content, the clusters expose more Ni atoms. The mechanistic pathways for CO₂ hydrogenation were computed for In₂O₃-supported Ni₂In₆ and Ni₆In₂ clusters, representing In-rich or Ni-rich clusters. Microkinetic simulations show that only the Ni₆In₂ cluster catalyzes methanol via hydrogenation of adsorbed CO₂ to formate, the precursor to methanol, by Ni-H species. Methanol formation competes with direct CO₂ dissociation, which becomes the dominant reaction pathway at high temperatures due to low H coverage. The supported Ni₂In₆ cluster exposes In atoms, which do not stabilize surface hydrides, explaining the low methanol activity and predominant CO formation.

Keywords: methanol; density functional theory; co2; in2o3; metal clusters