CLIII.—The thermal decomposition of ammonia upon various surfaces

Hinshelwood, Cyril Norman; Burk, Robert E.

doi:10.1039/ct9252701105

Cited by 75 publications

(25 citation statements)

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“…The decomposition of NH 3 has been studied under different conditions: thermal [1,2], catalytic [3,4], photo-chemical [5], and in plasma [6]. The kinetics and the reaction mechanism -even in the simplest case of thermal decomposition -have not yet been fully elucidated with several matters still in dispute.…”

Section: Introductionmentioning

confidence: 99%

Thermal decomposition of ammonia. N2H4-an intermediate reaction product

et al. 2006

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The paper reports the thermal decomposition of ammonia under dynamic conditions at 800• C in a quartz reactor. Its purpose is to confirm the homogeneous-heterogeneous degenerated branched chain mechanism established in previous studies, which assume the formation of N 2 H 4 as a molecular intermediate; this paper identifies hydrazine as a product of thermal decomposition using FT-IR and UV-VIS spectroscopies.

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Section: Introductionmentioning

confidence: 99%

Thermal decomposition of ammonia. N2H4-an intermediate reaction product

et al. 2006

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“…WsNH; both structures can account for the thermal desorption results but the magnitude of the hydrogen isotope effect involved in this reaction supports the first of these structures (10). In this case, the q-desorption process can be represented as The activation energy for the q-desorption process is 35 kcal mol-' (24), the same as that 1 observed for the overall decomposition process (1,2,4). It is possible to account for the desorption of hydrogen in the atomic state by assuming that the ability of adjacent tungsten atoms to participate in the breaking of the N-H bond is reduced to zero at this adatom density.…”

Section: Desorption Of Hydrogen Following Interaction Ofmentioning

confidence: 71%

The State of Hydrogen Desorbing from Intermediates Formed by Ammonia Interaction with Tungsten Surfaces

Yi¹,

Dawson²

1974

Can. J. Chem.

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Ammonia interaction with a tungsten surface can generate dense adlayers containing nitrogen and hydrogen, i.e. an η-species of surface stoichiometry Ws2N3H. In thermal desorption mass spectrometry experiments, hydrogen desorbing from the η-species interacts with the glass wall in a manner similar to that previously observed for atomic hydrogen. This paper describes two mass spectrometric techniques designed to confirm this conclusion directly. The first method uses a line-of-sight geometry between the tungsten filament and the ionization source of the mass spectrometer and the results indicate that, at least, part of the hydrogen desorbing from the η-species does so atomically. In the second method a multiple wall collision geometry is used but prior saturation of the wall with D atoms will result in an HD+ ion current for desorbing H atoms. The results suggest that 26% of the hydrogen desorbs atomically. Hydrogen atom desorption from the η-species occurs at tungsten filament temperatures below those required for hydrogen atom evaporation from a pure hydrogen adlayer. It is proposed that a reduced binding energy for adsorbed hydrogen atoms and a reduced mobility of these adatoms arises from the presence of a large surface concentration of nitrogen. This will result in the rates of atomic hydrogen desorption and bimolecular recombination becoming comparable at temperatures lower than is the case for pure hydrogen interaction with tungsten. The implications of these results for the ammonia synthesis reaction are discussed.

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“…would be more likely. Hinshelwood and Burk's study of the homogeneous decomposition 5 yielded the qualitative facts that the decomposition could not be detected below temperatures of about 1500 0 K., whereas above this temperature it was too fast to be measured with the equipment available to them at the time. (More recently, Sage, using a ballistic piston, found similarly that there was practically no conversion of NH3 below 1500°.6) Hinshelwood inferred from his study that an activation energy of at least 80 kcal.…”

Section: Resultsmentioning

confidence: 99%

Further Shock-Tube Studies by Infrared Emission of the Decomposition of Ammonia

Jacobs¹

1963

J. Phys. Chem.

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CLIII.—The thermal decomposition of ammonia upon various surfaces

Cited by 75 publications

References 0 publications

Thermal decomposition of ammonia. N2H4-an intermediate reaction product

Thermal decomposition of ammonia. N2H4-an intermediate reaction product

The State of Hydrogen Desorbing from Intermediates Formed by Ammonia Interaction with Tungsten Surfaces

Further Shock-Tube Studies by Infrared Emission of the Decomposition of Ammonia

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