Effect of potassium on the active phases of Fe catalysts for carbon dioxide conversion to liquid fuels through hydrogenation

Meital Amoyal; Roxana Vidruk-Nehemya; Miron V. Landau; Moti Herskowitz

doi:10.1016/j.jcat.2017.01.020

Effect of potassium on the active phases of Fe catalysts for carbon dioxide conversion to liquid fuels through hydrogenation

Meital Amoyal, Roxana Vidruk-Nehemya, Miron V. Landau, Moti Herskowitz

Department of Chemical Engineering

Research output: Contribution to journal › Article › peer-review

160 Scopus citations

Abstract

The effect of potassium was tested with unpromoted and K-promoted Fe-Al-O oxide and Fe₅C₂carbide materials, formed during CO₂hydrogenation from Fe-Al-O spinel. Each one of the tested catalysts contained a single phase (oxide or carbide). 2 wt% potassium enhanced the RWGS rate of reaction on the oxide phase tenfold compared with the unpromoted oxide. This correlated with increase of Fe²⁺/Fe³⁺ratio (XPS) determining oxygen vacancies as active sites for RWGS. Potassium suppressed the methanation rate on the carbide catalyst by a factor of five and increased the CO FTS rate to C₂₊hydrocarbons by a factor of 1.4. EFTEM images and elemental profiles of unpromoted carbide nanocrystals measured after testing in CO hydrogenation displayed an amorphous surface layer enriched with oxygen. Potassium stabilized the surface iron atoms in reduced form. The observed effects of potassium on carbide phase were explained by a model implementing carbon vacancies for methanation and near-metallic iron atoms for FTS.

Original language	English
Pages (from-to)	29-39
Number of pages	11
Journal	Journal of Catalysis
Volume	348
DOIs	https://doi.org/10.1016/j.jcat.2017.01.020
State	Published - 1 Jan 2017

Keywords

Carbon dioxide hydrogenation
FTS
Oxide and carbide iron
Potassium
RWGS

ASJC Scopus subject areas

Catalysis
Physical and Theoretical Chemistry

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.jcat.2017.01.020

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title = "Effect of potassium on the active phases of Fe catalysts for carbon dioxide conversion to liquid fuels through hydrogenation",

abstract = "The effect of potassium was tested with unpromoted and K-promoted Fe-Al-O oxide and Fe5C2carbide materials, formed during CO2hydrogenation from Fe-Al-O spinel. Each one of the tested catalysts contained a single phase (oxide or carbide). 2 wt% potassium enhanced the RWGS rate of reaction on the oxide phase tenfold compared with the unpromoted oxide. This correlated with increase of Fe2+/Fe3+ratio (XPS) determining oxygen vacancies as active sites for RWGS. Potassium suppressed the methanation rate on the carbide catalyst by a factor of five and increased the CO FTS rate to C2+hydrocarbons by a factor of 1.4. EFTEM images and elemental profiles of unpromoted carbide nanocrystals measured after testing in CO hydrogenation displayed an amorphous surface layer enriched with oxygen. Potassium stabilized the surface iron atoms in reduced form. The observed effects of potassium on carbide phase were explained by a model implementing carbon vacancies for methanation and near-metallic iron atoms for FTS.",

keywords = "Carbon dioxide hydrogenation, FTS, Oxide and carbide iron, Potassium, RWGS",

author = "Meital Amoyal and Roxana Vidruk-Nehemya and Landau, {Miron V.} and Moti Herskowitz",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier Inc.",

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doi = "10.1016/j.jcat.2017.01.020",

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AU - Amoyal, Meital

AU - Vidruk-Nehemya, Roxana

AU - Landau, Miron V.

AU - Herskowitz, Moti

PY - 2017/1/1

Y1 - 2017/1/1

N2 - The effect of potassium was tested with unpromoted and K-promoted Fe-Al-O oxide and Fe5C2carbide materials, formed during CO2hydrogenation from Fe-Al-O spinel. Each one of the tested catalysts contained a single phase (oxide or carbide). 2 wt% potassium enhanced the RWGS rate of reaction on the oxide phase tenfold compared with the unpromoted oxide. This correlated with increase of Fe2+/Fe3+ratio (XPS) determining oxygen vacancies as active sites for RWGS. Potassium suppressed the methanation rate on the carbide catalyst by a factor of five and increased the CO FTS rate to C2+hydrocarbons by a factor of 1.4. EFTEM images and elemental profiles of unpromoted carbide nanocrystals measured after testing in CO hydrogenation displayed an amorphous surface layer enriched with oxygen. Potassium stabilized the surface iron atoms in reduced form. The observed effects of potassium on carbide phase were explained by a model implementing carbon vacancies for methanation and near-metallic iron atoms for FTS.

AB - The effect of potassium was tested with unpromoted and K-promoted Fe-Al-O oxide and Fe5C2carbide materials, formed during CO2hydrogenation from Fe-Al-O spinel. Each one of the tested catalysts contained a single phase (oxide or carbide). 2 wt% potassium enhanced the RWGS rate of reaction on the oxide phase tenfold compared with the unpromoted oxide. This correlated with increase of Fe2+/Fe3+ratio (XPS) determining oxygen vacancies as active sites for RWGS. Potassium suppressed the methanation rate on the carbide catalyst by a factor of five and increased the CO FTS rate to C2+hydrocarbons by a factor of 1.4. EFTEM images and elemental profiles of unpromoted carbide nanocrystals measured after testing in CO hydrogenation displayed an amorphous surface layer enriched with oxygen. Potassium stabilized the surface iron atoms in reduced form. The observed effects of potassium on carbide phase were explained by a model implementing carbon vacancies for methanation and near-metallic iron atoms for FTS.

KW - Carbon dioxide hydrogenation

KW - FTS

KW - Oxide and carbide iron

KW - Potassium

KW - RWGS

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DO - 10.1016/j.jcat.2017.01.020

M3 - Article

AN - SCOPUS:85014152775

SN - 0021-9517

VL - 348

SP - 29

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JO - Journal of Catalysis

JF - Journal of Catalysis

ER -

Effect of potassium on the active phases of Fe catalysts for carbon dioxide conversion to liquid fuels through hydrogenation

Abstract

Keywords

ASJC Scopus subject areas

UN SDGs

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