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Open AccessArticle

Cr-Free, Cu Promoted Fe Oxide-Based Catalysts for High-Temperature Water-Gas Shift (HT-WGS) Reaction

Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical & Biomolecular Engineering, Lehigh University, Bethlehem, PA-18015, USA
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Catalysts 2020, 10(3), 305; https://doi.org/10.3390/catal10030305
Received: 19 February 2020 / Revised: 29 February 2020 / Accepted: 4 March 2020 / Published: 6 March 2020
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
Ca, Ni, Co, and Ge promoters were examined as potential candidates to substitute for the current toxic Cr in Cu-promoted Fe oxide-based catalysts for the HT-WGS reaction. The Ca and Ni promoters were found to improve catalyst performance relative to promotion with Cr. The HS-LEIS surface analysis data demonstrate that Ca and Ge tend to segregate on the surface, while Ni, Co, and Cr form solid solutions in the Fe3O4 bulk lattice. The corresponding number of catalytic active sites, redox, and WGS activity values of the catalysts were determined with CO-TPR, CO+H2O-TPSR, and SS-WGS studies, respectively. The poorer HT-WGS performances of the Ge and Co promoters are related to the presence of surface Ge and Co that inhibits catalyst redox ability, with the Co also not stabilizing the surface area of the Fe3O4 support. The Ni promoter uniformly disperses the Cu nanoparticles on the catalyst surface and increases the number of FeOx-Cu interfacial redox sites. The Ca promoter on the catalyst surface, however, enhances the activity of the FeOx-Cu interfacial redox sites. The CO+H2O TPSR results reveal that the redox ability of the active sites follows the SS-WGS performance of the catalysts and show the following trend: 3Cu8CaFe > 3Cu8NiFe ≥ 3Cu8CrFe > 3Cu8CoFe >> 3Cu8GeFe. Furthermore, all the catalysts followed a redox-type reaction mechanism for the HT-WGS reaction. View Full-Text
Keywords: HT-WGS; Fe oxide-based catalysts; Cr-free catalysts; structure-function relationship HT-WGS; Fe oxide-based catalysts; Cr-free catalysts; structure-function relationship
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Sourav, S.; Wachs, I.E. Cr-Free, Cu Promoted Fe Oxide-Based Catalysts for High-Temperature Water-Gas Shift (HT-WGS) Reaction. Catalysts 2020, 10, 305.

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