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Main Title: Influence of Phase Composition and Pretreatment on the Conversion of Iron Oxides into Iron Carbides in Syngas Atmospheres
Author(s): Arinchtein, Aleks
Ye, Meng-Yang
Geske, Michael
Frisch, Marvin
Kraehnert, Ralph
Type: Article
Abstract: CO2 Fischer–Tropsch synthesis (CO2–FTS) is a promising technology enabling conversion of CO2 into valuable chemical feedstocks via hydrogenation. Iron–based CO2–FTS catalysts are known for their high activities and selectivities towards the formation of higher hydrocarbons. Importantly, iron carbides are the presumed active phase strongly associated with the formation of higher hydrocarbons. Yet, many factors such as reaction temperature, atmosphere, and pressure can lead to complex transformations between different oxide and/or carbide phases, which, in turn, alter selectivity. Thus, understanding the mechanism and kinetics of carbide formation remains challenging. We propose model–type iron oxide films of controlled nanostructure and phase composition as model materials to study carbide formation in syngas atmospheres. In the present work, different iron oxide precursor films with controlled phase composition (hematite, ferrihydrite, maghemite, maghemite/magnetite) and ordered mesoporosity are synthesized using the evaporation–induced self–assembly (EISA) approach. The model materials are then exposed to a controlled atmosphere of CO/H2 at 300 °C. Physicochemical analysis of the treated materials indicates that all oxides convert into carbides with a core–shell structure. The structure appears to consist of crystalline carbide cores surrounded by a partially oxidized carbide shell of low crystallinity. Larger crystallites in the original iron oxide result in larger carbide cores. The presented simple route for the synthesis and analysis of soft–templated iron carbide films will enable the elucidation of the dynamics of the oxide to carbide transformation in future work.
Subject(s): CO2 Fischer–Tropsch synthesis
iron oxide
iron carbides
mesoporous films
Issue Date: 25-Jun-2021
Date Available: 26-Jul-2021
Language Code: en
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: DFG, 406695057, Fe-basierte Katalysatoren für die Umwandlung von CO2 zu höheren Kohlenwasserstoffen unter dynamischen Bedingungen
BMBF, 03EK3052A, Verbundvorhaben ATO-KAT: Atomar dünn beschichtete poröse Elektroden als neuartige Katalysatoren für die Wasser-Elektrolyse: - leitfähige Träger und Elektrochemie -
DFG, 414044773, Open Access Publizieren 2021 - 2022 / Technische Universität Berlin
Journal Title: Catalysts
Publisher: MDPI
Volume: 11
Issue: 7
Article Number: 773
Publisher DOI: 10.3390/catal11070773
EISSN: 2073-4344
TU Affiliation(s): Verbundforschung » Exzellenzcluster (EXC) » BasCat Joint Lab
Appears in Collections:Technische Universität Berlin » Publications

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