Air separation via two-step solar thermochemical cycles based on SrFeO3−δ and (Ba,La)0.15Sr0.85FeO3−δ perovskite reduction/oxidation reactions to produce N2: rate limiting mechanism(s) determination

Nguyen, Nhu Pailes; Farr, Tyler; Bush, H. Evan; Ambrosini, Andrea; Loutzenhiser, Peter G.

doi:10.1039/d1cp03303d

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…This chemical looping approach should be amenable to integration with green resources, including green H 2 and N 2 , and renewable energy input. A solar thermochemical process that encompasses H 2 and N 2 − production while supplying energy for the above chemical looping approach, for example, may be a promising candidate for carbon-neutral NH 3 synthesis.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

et al. 2023

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Over the past few decades, inorganic nitride materials have grown in importance in part due to their potential as catalysts for the synthesis of NH3, a key ingredient in fertilizer and precursor to industrial chemicals. Of particular interest are the ternary (ABN) or higher-order nitrides with high metal-to-nitrogen ratios that show promise in enhancing NH3 synthesis reaction rates and yields via heterogeneous catalysis or chemical looping. Although metal nitrides are predicted to be numerous, the stability of nitrogen triple bonds found in N2, especially in comparison to the metal–nitrogen bonds, has considerably hindered synthetic efforts to produce complex nitride compounds. In this study, we present an exhaustive down-selection process to identify ternary nitrides for a promising chemical looping NH3 production mechanism. We also report on a facile and efficient two-step synthesis method that can produce well-characterized η-carbide Co3Mo3N/Fe3Mo3N or filled β-manganese Ni2Mo3N ternaries, as well as their associated quaternary, (Co,Fe)3Mo3N, (Fe,Ni)2Mo3N, and (Co,Ni)2Mo3N, solid solutions. To further explore the quaternary space, syntheses of (Co,Ni)3Mo3N (Ni ≤ 10 mol %) and Co3(Mo,W)3N (W ≤ 10 mol %) were also investigated. The structures of the nitrides were characterized via X-ray powder diffraction. The morphology and compositions were characterized with scanning electron microscopy. The multitude of chemically unique, but structurally related, nitrides suggests that properties such as nitrogen activity may be tunable, making the materials of great interest for NH3 synthesis schemes.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

et al. 2023

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“…The schematic of the complete cycle is shown in Figure 1. The thermochemical looping cycle becomes renewable when the N 2 is derived from solar thermochemical air separation, [21][22][23][24] the H 2 from solar thermochemical H 2 O splitting, [25][26][27] and the process heat from CST. [28,29] NH 3 production was previously proposed with a fixed particle bed reactor directly coupled to CST technologies.…”

Section: Introductionmentioning

confidence: 99%

Two‐Step Chemical Looping Cycle for Renewable NH₃ Production Based on Non‐Catalytic Co₃Mo₃N/Co₆Mo₆N Reactions

Nguyen,

Kaur,

Bush

et al. 2023

Advanced Energy Materials

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A two‐step solar thermochemical looping cycle based on Co3Mo3N/Co6Mo6N reduction/nitridation reactions offers a pathway for green NH3 production that utilizes concentrated solar irradiation, H2O, and air as feedstocks. The NH3 production cycle steps both derive process heat from concentrated solar irradiation and encompass 1) the reduction of Co3Mo3N in H2 to Co6Mo6N and NH3; and 2) nitridation of Co6Mo6N to Co3Mo3N with N2. Co3Mo3N reduction/nitridation reactions are examined at different H2 and/or N2 partial pressures and temperatures. NH3 production is quantified in situ using liquid conductivity measurements coupled with mass spectrometry (MS). Solid‐state characterization is performed to identify a surface oxygen layer that necessitates the addition of H2 during cycling to prevent surface oxidation by trace amounts of O2. H2 concentrations of > 5% H2/Ar and temperatures >500 °C are required to reduce Co3Mo3N to Co6Mo6N and form NH3 at 1 bar. Complete regeneration of Co3Mo3N from Co6Mo6N is achieved at conditions of 700 °C under 25–75% H2/N2. H2 pressure‐swings are observed to increase NH3 production during Co3Mo3N reduction. The results represent the first comprehensive characterization of and definitive non‐catalytic production of NH3 via chemical looping with metal nitrides and provide insights for technology development.

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“…These materials have also received great attention as oxygen carriers for other processes: ternary oxides with a perovskite structure ABO 3 are frequently reported for chemical looping applications 4 and air separation. 5 Furthermore, perovskites also offer the potential of storing heat in a broad temperature range. 6 T h i s c o n t e n t i s Based on this background, the La 0.8 Sr 0.2 Co 0.2 Fe 0.8 O 3−δ (LSCF) perovskite material was chosen as the starting point for a preliminary assessment of its suitability for the solar thermochemical water-splitting cycle.…”

Section: ■ Introductionmentioning

confidence: 99%

“…This technology is based on the ability of nonstoichiometric metal oxides to release and capture oxygen by creating and destroying oxygen vacancies in the crystal lattice AB O 3 ( s ) ⇌ AB O 3 − δ ( s ) + δ / 2 O 2 ( g ) ABO 3 − δ ( s ) + δ H 2 normalO ⇌ AB O 3 ( s ) + δ H 2 ( g ) where δ is the reaction extent that depends on conditions of temperature and oxygen partial pressure ( p O 2 ). These materials have also received great attention as oxygen carriers for other processes: ternary oxides with a perovskite structure ABO 3 are frequently reported for chemical looping applications and air separation . Furthermore, perovskites also offer the potential of storing heat in a broad temperature range …”

Section: Introductionmentioning

confidence: 99%

Perovskite Materials for Solar Thermochemical Fuel Production: Enhancement of Fuel Productivity by Acid Etching

Vidal

2023

Energy Fuels

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Reducing greenhouse gas emissions is one of the greatest challenges facing society today. Limiting global warming requires a significant reduction in the use of fossil fuels, an increase in renewable energy, and the search for alternative fuels. Hydrogen is emerging as the energy carrier of the future with zero CO 2 emissions when produced from renewable energy. This sustainable economy based on renewable hydrogen would require large-scale hydrogen production processes, such as solar-driven thermochemical cycles based on metal oxides, which have been proposed as a promising alternative for clean hydrogen production. Recently, perovskite systems have attracted interest as promising candidates for thermochemical cycles. In this work, the La 0.8 Sr 0.2 Co 0.2 Fe 0.8 O 3−δ (LSCF) perovskite material has been chosen as a starting point for a preliminary assessment of its suitability as a material candidate for solar thermochemical water-splitting cycles. This material not only exhibits high oxygen exchange capacities but also suffers from redox kinetic limitations of the water-splitting reaction. Through this work, a potential improvement of the oxidation reaction of the perovskite-based thermochemical cycle was pursued. A new way of tuning the surface of the perovskite oxide by acid etching is presented here to manipulate the material properties of perovskite oxides.

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Air separation via two-step solar thermochemical cycles based on SrFeO_3−δ and (Ba,La)_0.15Sr_0.85FeO_3−δ perovskite reduction/oxidation reactions to produce N₂: rate limiting mechanism(s) determination

Abstract: Two-step solar thermochemical cycles based on reversible reactions of SrFeO3-δ and (Ba,La)0.15Sr0.85FeO3-δ perovskites were considered for air separation. The cycle steps encompass (1) the thermal reduction of SrFeO3-δ or (Ba,La)0.15Sr0.85FeO3-δ...

Cited by 7 publications

References 34 publications

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

Two‐Step Chemical Looping Cycle for Renewable NH₃ Production Based on Non‐Catalytic Co₃Mo₃N/Co₆Mo₆N Reactions

Perovskite Materials for Solar Thermochemical Fuel Production: Enhancement of Fuel Productivity by Acid Etching

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Air separation via two-step solar thermochemical cycles based on SrFeO3−δ and (Ba,La)0.15Sr0.85FeO3−δ perovskite reduction/oxidation reactions to produce N2: rate limiting mechanism(s) determination

Abstract: Two-step solar thermochemical cycles based on reversible reactions of SrFeO3-δ and (Ba,La)0.15Sr0.85FeO3-δ perovskites were considered for air separation. The cycle steps encompass (1) the thermal reduction of SrFeO3-δ or (Ba,La)0.15Sr0.85FeO3-δ...

Cited by 7 publications

References 34 publications

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

Synthesis and Structural Study of Substituted Ternary Nitrides for Ammonia Production

Two‐Step Chemical Looping Cycle for Renewable NH3 Production Based on Non‐Catalytic Co3Mo3N/Co6Mo6N Reactions

Perovskite Materials for Solar Thermochemical Fuel Production: Enhancement of Fuel Productivity by Acid Etching

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Air separation via two-step solar thermochemical cycles based on SrFeO_3−δ and (Ba,La)_0.15Sr_0.85FeO_3−δ perovskite reduction/oxidation reactions to produce N₂: rate limiting mechanism(s) determination

Two‐Step Chemical Looping Cycle for Renewable NH₃ Production Based on Non‐Catalytic Co₃Mo₃N/Co₆Mo₆N Reactions