Ammonia synthesis over Cs- or Ba-promoted ruthenium catalyst supported on strontium niobate

Chen, Minxuan; Yuan, Mingwei; Li, Jinjun; You, Zhixiong

doi:10.1016/j.apcata.2018.01.006

Cited by 29 publications

(5 citation statements)

References 55 publications

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“…Compared to other studies, the ex-Ru/BCY catalyst showed highly promising ammonia synthesis activity (Figure S4, Supporting Information) when the activity was normalized to the amount of Ru used, at 0.1 MPa. [9,10,[43][44][45][46][47][48][49][50][51][52][53] The catalysts were also compared with Ba-promoted Ru/C catalysts (Ba-Ru/C), which are commonly used catalysts for the ammonia synthesis reaction [54] (Figure S5, Supporting Information). The Ba promoter was introduced into the Ru/C catalyst using the incipient wetness impregnation method.…”

Section: Catalytic Activitymentioning

confidence: 99%

Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Kim

Jan

Kwon

et al. 2022

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Ammonia has been a crucial chemical for feeding the massive population growth in the twentieth century since its industrial production via the Haber-Bosch process. Ammonia, particularly "green" ammonia, has attracted significant interest as a carbon-free energy carrier. [1,2] Ammonia has one of the highest gravimetric (17.8 wt%) weight and volumetric (108 kg-H 2 m −3 NH 3 at 20 °C and 8.6 bar) energy density among carbon-free energy carriers. [3] The traditional Haber-Bosch process requires high temperatures to overcome the large reaction energy barrier for dissociating the stable nitrogen triple bond (NN). [4] However, exceedingly high pressure is also necessary to compensate for the low thermodynamic conversion ratio of the exothermic ammonia synthesis reaction at high temperatures. High temperature (450-600 °C) and high pressure (100-250 bar) requirements make the Haber-Bosch process economically viable only for extremely-large-scale systems. The production of "green" ammonia using hydrogen from water electrolysis requires a small-scale low-pressure reactor. [5] Water electrolysis typically operates below 30 bar and is coupled with intermittent renewable electricity at remote sites. [6] The need for a highly active ammonia synthesis catalyst is becoming increasingly important for reducing the operating temperature and pressure of the ammonia synthesis reaction.The ammonia synthesis rate follows a volcano plot, and optimizing the nitrogen adsorption energy is key to achieving high activity. [7,8] Ru shows superior activity among the studied transition metal catalysts. Therefore, supported Ru catalysts have been widely investigated for ammonia synthesis. [9][10][11][12][13][14] Two approaches are available to further the catalytic activity of Ru: i) structural modification and ii) electronic structure modification. Experiments and density functional theory calculations showed that the Ru B5-type surface structure facilitates the N 2 dissociation reaction, which is the rate-determining step for Ru. The density of the Ru B5 sites is nanoparticle size-dependent, Ru nanoparticles of 3-5 nm show the highest activity, [15,16] and the activity decreases with increasing size. [17] Electron-rich Ru increases activity by lowering the activation barrier during N 2 triple bond dissociation. Electronic structure promotion can be Green ammonia is an efficient, carbon-free energy carrier and storage medium. The ammonia synthesis using green hydrogen requires an active catalyst that operates under mild conditions. The catalytic activity can be promoted by controlling the geometry and electronic structure of the active species. An exsolution process is implemented to improve catalytic activity by modulating the geometry and electronic structure of Ru. Ru nanoparticles exsolved on a BaCe 0.9 Y 0.1 O 3-δ support exhibit uniform size distribution, 5.03 ± 0.91 nm, and exhibited one of the highest activities, 387.31 mmol NH3 g Ru −1 h −1 (0.1 MPa and 450 °C). The role of the exsolution and BaCe 0.9 Y 0.1 O 3-δ support is studied by ...

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Section: Catalytic Activitymentioning

confidence: 99%

Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Kim

Jan

Kwon

et al. 2022

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“…Although improvement in catalytic activity was observed when the exsolution temperature was increased from 650 to 800 °C owing to increased metal content, this came at the expense of decomposing the perovskite backbone to La 2 O 3 and FeO (Figures S11 and S12). Both La 2 O 3 and FeO are not capable of supporting the high concentrations of oxygen vacancies (OVs) compared to the perovskite phase, which can be detrimental to ammonia synthesis since they can act as active sites for nitrogen activation and cleavage. , While previous reports have shown that La 2 O 3 and SrO are effective promoters for Ru-based ammonia catalysis, , this report shows that maintaining the perovskite structure, rather than decomposing into the lanthanum or strontium oxides, is the preferred configuration. The ideal catalyst should therefore provide sufficient metal Ru, Fe, and Cu sites while still maintaining the perovskite backbone.…”

Section: Resultsmentioning

confidence: 69%

Ambient-Pressure Ammonia Thermocatalyst Prepared by Exsolution of Cu–Ru–Fe Heterostructures

Hirshberg,

Zucker,

Bereshit

et al. 2024

ACS Appl. Energy Mater.

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Ammonia synthesis is typically done by the Haber−Bosch process and is critical for sustainable agriculture. It additionally is gaining significant interest in the energy sector as a chemical hydrogen carrier. The Haber−Bosch process is an energy-intensive method for making ammonia; therefore, there is great interest in developing catalysts for the thermochemical production of ammonia at comparatively lower pressures and temperatures. This effort has been blocked by a lack of active catalysts, which can simultaneously activate nitrogen bond scission, relieve the effects of hydrogen poisoning, and maintain nanoscale stability for extended periods of time. Here, we report the exsolution of heterogeneously structured trimetallic Ru−Cu−Fe nanoparticles from lanthanum ferrate backbones. By exploiting the immiscibility regions in the Ru−Cu−Fe phase diagram, nanoscale catalytic heterostructures from these three metals were formed and found to catalyze thermochemical ammonia synthesis at atmospheric pressure (0.1 MPa) at 7.54 mmol/g cat /h. Copper, which is not active for ammonia synthesis, was shown to be a promoter by limiting the growth of Ru nanoparticles during exsolution to 2 nm owing to the immiscibility between Cu and Ru.

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“…SrO has good electron-donating capability, which modifies the electronic property of the catalyst and facilitates recombinative nitrogen desorption during the ADR. 39 However, excessive Sr also leads to decreased activity (Fig. S16, ESI †), either due to the formation of Sr(OH) 2 or an increase in CoNi crystallite size.…”

Section: Catalytic Activity and Stability For The Adrmentioning

confidence: 99%

Hydrogen generation via ammonia decomposition on highly efficient and stable Ru-free catalysts: approaching complete conversion at 450 °C

Tabassum

Mukherjee

Chen

et al. 2022

Energy Environ. Sci.

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Ammonia synthesis over Cs- or Ba-promoted ruthenium catalyst supported on strontium niobate

Cited by 29 publications

References 55 publications

Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Ambient-Pressure Ammonia Thermocatalyst Prepared by Exsolution of Cu–Ru–Fe Heterostructures

Hydrogen generation via ammonia decomposition on highly efficient and stable Ru-free catalysts: approaching complete conversion at 450 °C

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Ammonia synthesis over Cs- or Ba-promoted ruthenium catalyst supported on strontium niobate

Cited by 29 publications

References 55 publications

Exsolution of Ru Nanoparticles on BaCe0.9Y0.1O3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Exsolution of Ru Nanoparticles on BaCe0.9Y0.1O3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Ambient-Pressure Ammonia Thermocatalyst Prepared by Exsolution of Cu–Ru–Fe Heterostructures

Hydrogen generation via ammonia decomposition on highly efficient and stable Ru-free catalysts: approaching complete conversion at 450 °C

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Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions

Exsolution of Ru Nanoparticles on BaCe_0.9Y_0.1O_3‐δ Modifying Geometry and Electronic Structure of Ru for Ammonia Synthesis Reaction Under Mild Conditions