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Structure and Role of a Ga-Promoter in Ni-Based Catalysts for the Selective Hydrogenation of CO2 to Methanol.
Zimmerli, Nora K; Rochlitz, Lukas; Checchia, Stefano; Müller, Christoph R; Copéret, Christophe; Abdala, Paula M.
Afiliación
  • Zimmerli NK; Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, CH 8092 Zürich, Switzerland.
  • Rochlitz L; Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, CH 8093 Zürich, Switzerland.
  • Checchia S; ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France.
  • Müller CR; Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, CH 8092 Zürich, Switzerland.
  • Copéret C; Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, CH 8093 Zürich, Switzerland.
  • Abdala PM; Department of Mechanical and Process Engineering, ETH Zürich, Leonhardstrasse 21, CH 8092 Zürich, Switzerland.
JACS Au ; 4(1): 237-252, 2024 Jan 22.
Article en En | MEDLINE | ID: mdl-38274252
ABSTRACT
Supported, bimetallic catalysts have shown great promise for the selective hydrogenation of CO2 to methanol. In this study, we decipher the catalytically active structure of Ni-Ga-based catalysts. To this end, model Ni-Ga-based catalysts, with varying NiGa ratios, were prepared by a surface organometallic chemistry approach. In situ differential pair distribution function (d-PDF) analysis revealed that catalyst activation in H2 leads to the formation of nanoparticles based on a Ni-Ga face-centered cubic (fcc) alloy along with a small quantity of GaOx. Structure refinements of the d-PDF data enabled us to determine the amount of both alloyed Ga and GaOx species. In situ X-ray absorption spectroscopy experiments confirmed the presence of alloyed Ga and GaOx and indicated that alloying with Ga affects the electronic structure of metallic Ni (viz., Niδ-). Both the NiGa ratio in the alloy and the quantity of GaOx are found to minimize methanation and to determine the methanol formation rate and the resulting methanol selectivity. The highest formation rate and methanol selectivity are found for a Ni-Ga alloy having a NiGa ratio of ∼7525 along with a small quantity of oxidized Ga species (0.14 molNi-1). Furthermore, operando infrared spectroscopy experiments indicate that GaOx species play a role in the stabilization of formate surface intermediates, which are subsequently further hydrogenated to methoxy species and ultimately to methanol. Notably, operando XAS shows that alloying between Ni and Ga is maintained under reaction conditions and is key to attaining a high methanol selectivity (by minimizing CO and CH4 formation), while oxidized Ga species enhance the methanol formation rate.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: JACS Au Año: 2024 Tipo del documento: Article País de afiliación: Suiza Pais de publicación: Estados Unidos
Texto completo
Añadir a Mi BVS
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XML
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: JACS Au Año: 2024 Tipo del documento: Article País de afiliación: Suiza Pais de publicación: Estados Unidos