Dissociative and Associative Concerted Mechanism for Ammonia Synthesis over Co-Based Catalyst

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/LaCeOx 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 Ba2+, Ce3+ and La3+, 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.

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

10.26434/chemrxiv.7763657 ◽

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

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/LaCeOx 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 Ba2+, Ce3+ and La3+, 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.

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Effect of Hydrothermal Treatment of Activated Carbon by Nitric Acid on Activ-ity of Ba-Ru-K/AC Catalyst for Ammonia Synthesis

CHINESE JOURNAL OF CATALYSIS (CHINESE VERSION) ◽

10.3724/sp.j.1088.2012.20233 ◽

2013 ◽

Vol 33 (7) ◽

pp. 1191-1197

Author(s):

Guoquan FENG ◽

Guojun LAN ◽

Ying LI ◽

Wenfeng HAN ◽

Huazhang LIU

Keyword(s):

Activated Carbon ◽

Nitric Acid ◽

Hydrothermal Treatment ◽

Ammonia Synthesis

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Kinetic Studies of [4n+2]π-Thermal Cyclodimerization of 1-(3-Pyridazinyl)-3-oxidopyridinium Betaines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19921951 ◽

1992 ◽

Vol 57 (9) ◽

pp. 1951-1959 ◽

Cited By ~ 2

Author(s):

Madlene L. Iskander ◽

Samia A. El-Abbady ◽

Alyaa A. Shalaby ◽

Ahmed H. Moustafa

Keyword(s):

Energy Gap ◽

Activation Parameters ◽

Kinetic Studies ◽

Cyclic Transition ◽

Concerted Mechanism ◽

First Order ◽

Thermodynamic Activation Parameters ◽

Cyclic Transition State ◽

Complete Dissociation ◽

Homo Lumo

The reactivity of the base induced cyclodimerization of 1-(6-arylpyridazin-3-yl)-3-oxidopyridinium chlorides in a pericyclic process have been investigated kinetically at λ 380 nm. The reaction was found to be second order with respect to the liberated betaine and zero order with respect to the base. On the other hand dedimerization (monomer formation) was found to be first order. It was shown that dimerization is favoured at low temperature, whereas dedimerization process is favoured at relatively high temperature (ca 70 °C). Solvent effects on the reaction rate have been found to follow the order ethanol > chloroform ≈ 1,2-dichloroethane. Complete dissociation was accomplished only in 1,2-dichloroethane at ca 70 °C. The thermodynamic activation parameters have been calculated by a standard method. Thus, ∆G# has been found to be independent on substituents and solvents. The high negative values of ∆S# supports the cyclic transition state which is in favour with the concerted mechanism. MO calculations using SCF-PPP approximation method indicated low HOMO-LUMO energy gap of the investigated betaines.

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