Anisotropic N-Modification of the Mo4 Ensemble for Efficient Ammonia Synthesis on Molybdenum Nitrides

2019 ◽  
Vol 124 (1) ◽  
pp. 616-624 ◽  
Author(s):  
Jiankang Zhao ◽  
Chaonan Cui ◽  
Hua Wang ◽  
Jinyu Han ◽  
Xinli Zhu ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Molybdenum Nitrides

scholarly journals Chromium-modified cobalt molybdenum nitrides as catalysts for ammonia synthesis

2019 ◽  
Vol 17 (1) ◽  
pp. 127-131
Author(s):  
Paweł Adamski ◽  
Marlena Nadziejko ◽  
Agata Komorowska ◽  
Adam Sarnecki ◽  
Aleksander Albrecht ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Chromium Content ◽  
Ammonia Synthesis ◽  
Chromium Concentration ◽  
Synthesis Process ◽  
Pure Cobalt ◽  
Molybdenum Nitrides ◽  
Chromium Compounds

AbstractThe influence of chromium compounds on the properties of cobalt molybdenum nitrides was studied. CoMoO4 obtained by precipitation from cobalt and molybdenum salts was modified by the addition of chromium(III) nitrate. A mixture of cobalt-molybdenum nitrides, Co2Mo3N and Co3Mo3N, was formed by ammonolysis of modified CoMoO4. The concentration of Co2Mo3N decreases with increasing chromium content. The specific surface area of cobalt molybdenum nitrides consisting of 2 wt% of Cr atoms increased by 50% in comparison to pure cobalt molybdenum nitrides. The catalytic activity of obtained catalysts in ammonia synthesis process decreases with rising of chromium concentration.

Cobalt molybdenum nitrides co-promoted by chromium and potassium as catalysts for ammonia synthesis

2017 ◽  
Vol 72 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Dariusz Moszyński ◽  
Paweł Adamski ◽  
Marlena Nadziejko ◽  
Agata Komorowska ◽  
Adam Sarnecki
Keyword(s):  
Ammonia Synthesis ◽  
Molybdenum Nitrides

scholarly journals Thermal Stability of Potassium-Promoted Cobalt Molybdenum Nitride Catalysts for Ammonia Synthesis

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 100
Author(s):  
Paweł Adamski ◽  
Wojciech Czerwonko ◽  
Dariusz Moszyński
Keyword(s):  
Thermal Stability ◽  
Alkali Metals ◽  
Ammonia Synthesis ◽  
Stability Test ◽  
Molybdenum Nitride ◽  
Molybdenum Nitrides ◽  
Cobalt Molybdenum Nitride ◽  
Synthesis Catalysts ◽  
Two Phases ◽  
The Stability

The application of cobalt molybdenum nitrides as ammonia synthesis catalysts requires further development of the optimal promoter system, which enhances not only the activity but also the stability of the catalysts. To do so, elucidating the influence of the addition of alkali metals on the structural properties of the catalysts is essential. In this study, potassium-promoted cobalt molybdenum nitrides were synthesized by impregnation of the precursor CoMoO4·3/4H2O with aqueous KNO3 solution followed by ammonolysis. The catalysts were characterized with the use of XRD and BET methods, under two conditions: as obtained and after the thermal stability test. The catalytic activity in the synthesis of ammonia was examined at 450 °C, under 10 MPa. The thermal stability test was carried out by heating at 650 °C in the same apparatus. As a result of ammonolysis, mixtures of two phases: Co3Mo3N and Co2Mo3N were obtained. The phase concentrations were affected by potassium admixture. The catalytical activity increased for the most active catalyst by approximately 50% compared to non-promoted cobalt molybdenum nitrides. The thermal stability test resulted in a loss of activity, on average, of 30%. Deactivation was caused by the collapse of the porous structure, which is attributed to the conversion of the Co2Mo3N phase to the Co3Mo3N phase.

scholarly journals Thermal stability of catalyst for ammonia synthesis based on cobalt molybdenum nitrides

2018 ◽  
Vol 73 (4) ◽  
pp. 851-859 ◽  
Author(s):  
Paweł Adamski ◽  
Dariusz Moszyński ◽  
Marlena Nadziejko ◽  
Agata Komorowska ◽  
Adam Sarnecki ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ammonia Synthesis ◽  
Molybdenum Nitrides ◽  
Thermal Stability Of

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

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