Synthesis of ammonia directly from wet nitrogen using a redox stable La 0.75 Sr 0.25 Cr 0.5 Fe 0.5 O 3− δ–Ce 0.8 Gd 0.18 Ca 0.02 O 2− δ composite cathode

Ibrahim A Amar, Rong Lan, Shanwen Tao

    Research output: Contribution to journalArticle

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    Abstract

    Ammonia was directly synthesised from wet nitrogen at an intermediate temperature (375–425 °C) based on the oxygen-ion conduction of the Ce0.8Gd0.18Ca0.02O2−δ–((Li/Na/K)2CO3) composite electrolyte. A redox stable perovskite-based catalyst, La0.75Sr0.25Cr0.5Fe0.5O3−δ (LSCrF), was synthesised via a combined EDTA–citrate complexing sol–gel process to be used as a component of the La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode for ammonia synthesis. Ammonia formation was studied at 375, 400 and 425 °C and a maximum ammonia formation rate of 4.0 × 10−10 mol s−1 cm−2 with corresponding Faradaic efficiency of 3.87% was observed at 375 °C when the applied voltage was 1.4 V. This is much higher than 7.0 × 10−11 mol s−1 cm−2 at 1.4 V and 400 °C when Cr-free Sr-doped LaFeO3−δ, La0.6Sr0.4FeO3−δ was used as the catalyst for the electrochemical synthesis of ammonia, indicating LSCrF is potentially a better catalyst. Ammonia was successfully synthesised using a redox stable cathode with higher formation rates at reduced temperature. Introduction of Cr3+ ions at the B-site of doped LaFeO3 improves both the chemical stability and catalytic activity for ammonia synthesis.

    Graphical abstract: Synthesis of ammonia directly from wet nitrogen using a redox stable La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode
    Original languageEnglish
    Pages (from-to)38977-38983
    Number of pages7
    JournalRSC Advances
    Volume5
    Issue number49
    DOIs
    Publication statusPublished - May 2015

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    Ammonia
    Cathodes
    Nitrogen
    Composite materials
    Catalysts
    Ions
    Oxidation-Reduction
    Chemical stability
    Perovskite
    Electrolytes
    Catalyst activity
    Oxygen
    Temperature
    Electric potential

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    Synthesis of ammonia directly from wet nitrogen using a redox stable La 0.75 Sr 0.25 Cr 0.5 Fe 0.5 O 3− δ–Ce 0.8 Gd 0.18 Ca 0.02 O 2− δ composite cathode. / Amar, Ibrahim A; Lan, Rong; Tao, Shanwen .

    In: RSC Advances, Vol. 5, No. 49, 05.2015, p. 38977-38983.

    Research output: Contribution to journalArticle

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    title = "Synthesis of ammonia directly from wet nitrogen using a redox stable La 0.75 Sr 0.25 Cr 0.5 Fe 0.5 O 3− δ–Ce 0.8 Gd 0.18 Ca 0.02 O 2− δ composite cathode",
    abstract = "Ammonia was directly synthesised from wet nitrogen at an intermediate temperature (375–425 °C) based on the oxygen-ion conduction of the Ce0.8Gd0.18Ca0.02O2−δ–((Li/Na/K)2CO3) composite electrolyte. A redox stable perovskite-based catalyst, La0.75Sr0.25Cr0.5Fe0.5O3−δ (LSCrF), was synthesised via a combined EDTA–citrate complexing sol–gel process to be used as a component of the La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode for ammonia synthesis. Ammonia formation was studied at 375, 400 and 425 °C and a maximum ammonia formation rate of 4.0 × 10−10 mol s−1 cm−2 with corresponding Faradaic efficiency of 3.87{\%} was observed at 375 °C when the applied voltage was 1.4 V. This is much higher than 7.0 × 10−11 mol s−1 cm−2 at 1.4 V and 400 °C when Cr-free Sr-doped LaFeO3−δ, La0.6Sr0.4FeO3−δ was used as the catalyst for the electrochemical synthesis of ammonia, indicating LSCrF is potentially a better catalyst. Ammonia was successfully synthesised using a redox stable cathode with higher formation rates at reduced temperature. Introduction of Cr3+ ions at the B-site of doped LaFeO3 improves both the chemical stability and catalytic activity for ammonia synthesis.Graphical abstract: Synthesis of ammonia directly from wet nitrogen using a redox stable La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode",
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    T1 - Synthesis of ammonia directly from wet nitrogen using a redox stable La 0.75 Sr 0.25 Cr 0.5 Fe 0.5 O 3− δ–Ce 0.8 Gd 0.18 Ca 0.02 O 2− δ composite cathode

    AU - Amar, Ibrahim A

    AU - Lan, Rong

    AU - Tao, Shanwen

    PY - 2015/5

    Y1 - 2015/5

    N2 - Ammonia was directly synthesised from wet nitrogen at an intermediate temperature (375–425 °C) based on the oxygen-ion conduction of the Ce0.8Gd0.18Ca0.02O2−δ–((Li/Na/K)2CO3) composite electrolyte. A redox stable perovskite-based catalyst, La0.75Sr0.25Cr0.5Fe0.5O3−δ (LSCrF), was synthesised via a combined EDTA–citrate complexing sol–gel process to be used as a component of the La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode for ammonia synthesis. Ammonia formation was studied at 375, 400 and 425 °C and a maximum ammonia formation rate of 4.0 × 10−10 mol s−1 cm−2 with corresponding Faradaic efficiency of 3.87% was observed at 375 °C when the applied voltage was 1.4 V. This is much higher than 7.0 × 10−11 mol s−1 cm−2 at 1.4 V and 400 °C when Cr-free Sr-doped LaFeO3−δ, La0.6Sr0.4FeO3−δ was used as the catalyst for the electrochemical synthesis of ammonia, indicating LSCrF is potentially a better catalyst. Ammonia was successfully synthesised using a redox stable cathode with higher formation rates at reduced temperature. Introduction of Cr3+ ions at the B-site of doped LaFeO3 improves both the chemical stability and catalytic activity for ammonia synthesis.Graphical abstract: Synthesis of ammonia directly from wet nitrogen using a redox stable La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode

    AB - Ammonia was directly synthesised from wet nitrogen at an intermediate temperature (375–425 °C) based on the oxygen-ion conduction of the Ce0.8Gd0.18Ca0.02O2−δ–((Li/Na/K)2CO3) composite electrolyte. A redox stable perovskite-based catalyst, La0.75Sr0.25Cr0.5Fe0.5O3−δ (LSCrF), was synthesised via a combined EDTA–citrate complexing sol–gel process to be used as a component of the La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode for ammonia synthesis. Ammonia formation was studied at 375, 400 and 425 °C and a maximum ammonia formation rate of 4.0 × 10−10 mol s−1 cm−2 with corresponding Faradaic efficiency of 3.87% was observed at 375 °C when the applied voltage was 1.4 V. This is much higher than 7.0 × 10−11 mol s−1 cm−2 at 1.4 V and 400 °C when Cr-free Sr-doped LaFeO3−δ, La0.6Sr0.4FeO3−δ was used as the catalyst for the electrochemical synthesis of ammonia, indicating LSCrF is potentially a better catalyst. Ammonia was successfully synthesised using a redox stable cathode with higher formation rates at reduced temperature. Introduction of Cr3+ ions at the B-site of doped LaFeO3 improves both the chemical stability and catalytic activity for ammonia synthesis.Graphical abstract: Synthesis of ammonia directly from wet nitrogen using a redox stable La0.75Sr0.25Cr0.5Fe0.5O3−δ–Ce0.8Gd0.18Ca0.02O2−δ composite cathode

    U2 - 10.1039/C5RA00600G

    DO - 10.1039/C5RA00600G

    M3 - Article

    VL - 5

    SP - 38977

    EP - 38983

    JO - RSC Advances

    JF - RSC Advances

    SN - 2046-2069

    IS - 49

    ER -