Adjusting CO2 hydrogenation pathway via synergic effects of iron carbide and iron oxide

2021 ◽  
Author(s):  
Fangxu Lu ◽  
Xin Chen ◽  
Wen Wang ◽  
Yi Zhang
Keyword(s):  
Iron Oxide ◽  
Thermodynamic Stability ◽  
Iron Carbide ◽  
Co2 Hydrogenation ◽  
Co2 Reactivity ◽  
Chemical Inertness

Owing to the chemical inertness and thermodynamic stability of CO2, efficiently regulate the products selectivity in CO2 hydrogenation is still a big challenge. Without impairing the CO2 reactivity and stability,...

scholarly journals Influence of Phase Composition and Pretreatment on the Conversion of Iron Oxides into Iron Carbides in Syngas Atmospheres

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 773
Author(s):  
Aleks Arinchtein ◽  
Meng-Yang Ye ◽  
Michael Geske ◽  
Marvin Frisch ◽  
Ralph Kraehnert
Keyword(s):  
Phase Composition ◽  
Iron Oxide ◽  
Self Assembly ◽  
Iron Carbide ◽  
Active Phase ◽  
Physicochemical Analysis ◽  
Carbide Formation ◽  
Iron Carbides ◽  
Carbide Phases ◽  
Higher Hydrocarbons

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.

Electron Energy Loss Spectroscopy (EELS) of Iron Fischer–Tropsch Catalysts

2006 ◽  
Vol 12 (2) ◽  
pp. 124-134 ◽  
Author(s):  
Yaming Jin ◽  
Huifang Xu ◽  
Abhaya K. Datye
Keyword(s):  
Iron Oxide ◽  
Energy Loss ◽  
Electron Energy ◽  
Amorphous Carbon ◽  
Electron Energy Loss Spectroscopy ◽  
Iron Carbide ◽  
Iron Catalysts ◽  
Fischer Tropsch ◽  
Iron Phase ◽  
Electron Energy Loss

Electron energy loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy have been used to study iron catalysts for Fischer–Tropsch synthesis. When silica-containing iron oxide precursors are activated in flowing CO, the iron phase segregates into iron carbide crystallites, leaving behind some unreduced iron oxide in an amorphous state coexisting with the silica binder. The iron carbide crystallites are found covered by characteristic amorphous carbonaceous surface layers. These amorphous species are difficult to analyze by traditional catalyst characterization techniques, which lack spatial resolution. Even a surface-sensitive technique such as XPS shows only broad carbon or iron peaks in these catalysts. As we show in this work, EELS allows us to distinguish three different carbonaceous species: reactive amorphous carbon, graphitic carbon, and carbidic carbon in the bulk of the iron carbide particles. The carbidic carbon K edge shows an intense “π*” peak with an edge shift of about 1 eV to higher energy loss compared to that of the π* of amorphous carbon film or graphitic carbon. EELS analysis of the oxygen K edge allows us to distinguish the amorphous unreduced iron phase from the silica binder, indicating these are two separate phases. These results shed light onto the complex phase transformations that accompany the activation of iron catalysts for Fischer–Tropsch synthesis.

Low Temperature Formation of Iron Carbide from Iron Oxide with CO-H2Gas Mixtures

2007 ◽  
Vol 78 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Alberto N. Conejo ◽  
Raul S. Estrada
Keyword(s):  
Iron Oxide ◽  
Low Temperature ◽  
Iron Carbide

Study of carbon encapsulated iron oxide/iron carbide nanocomposite for hyperthermia

2012 ◽  
Vol 324 (23) ◽  
pp. 3975-3980 ◽  
Author(s):  
Madhulika Sharma ◽  
Sanket Mantri ◽  
D. Bahadur
Keyword(s):  
Iron Oxide ◽  
Iron Carbide

scholarly journals Micelle Encapsulation of Ferromagnetic Nanoparticles of Iron Carbide@Iron Oxide in Chitosan as Possible Nanomedicine Agent

2020 ◽  
Vol 4 (2) ◽  
pp. 22
Author(s):  
Perla Yazmin Sauceda-Oloño ◽  
Hector Cardenas-Sanchez ◽  
Anya Isabel Argüelles-Pesqueira ◽  
Cindy Gutierrez-Valenzuela ◽  
Mario Enrique Alvarez-Ramos ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Iron Oxide ◽  
Iron Carbide ◽  
Sodium Dodecylsulfate ◽  
Chemical Properties ◽  
Chitosan Solution ◽  
Iron Pentacarbonyl ◽  
Hydrodynamic Diameter ◽  
Shell Nanoparticles ◽  
Physical And Chemical

In this work, the synthesis and characterization of core/shell nanoparticles of iron carbide@iron oxide (Fe3C/γ-Fe2O3) encapsulated into micelles of sodium dodecylsulfate and oleic acid and stabilized with chitosan was developed. The materials were sonosynthesized at low intensities using standard ultrasonic baths with iron pentacarbonyl (Fe(CO)5) and oleic acid as iron source and hydrophobic stabilizer, respectively; obtaining nanoparticles with a hydrodynamic diameter of 19.71 nm and polydispersive index (PDI) of 0.13. The iron carbide@iron oxide nanoparticles (ICIONPs) in oleic acid were used as the organic phase during the self-assemble of nanoemulsion with sodium dodecylsulfate in water to obtain the metastable micelles. The final step involved the stabilization of the micelles using low molecular weight chitosan solution at 2% in acetic acid by ultrasonication bath. The nanosystem showed a hydrodynamic diameter of 185.30 nm, a PDI of 0.15 with a superficial charge ζ of 36.70 mV. Due to the magnetic, physical and chemical properties previously measured of the ICIONPs, it is believed that this type of nanoparticles can be used as a possible nanomedicine agent.

Structure sensitivity of iron oxide catalyst for CO2 hydrogenation

2020 ◽  
Author(s):  
Ruwei Yao ◽  
Jian Wei ◽  
Qingjie Ge ◽  
Jing Xu ◽  
Yu Han ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Oxide Catalyst ◽  
Co2 Hydrogenation ◽  
Structure Sensitivity ◽  
Iron Oxide Catalyst
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