Decomposition of hydrazine on Ir

Papapolymerou, G.; Botis, A. G.; Papargyris, Athanasios D.; Spiliotis, X.; Kasidakis, D.

doi:10.1007/bf02067701

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…It is also known that Ir shows catalytic behavior for hydrazine (as well as other species such as hydrocarbons) in many other environments. These include polycrystalline or (111) Ir surfaces [36][37][38][39], as well as Ir particles supported on carbon nanofibers [40], MgO [41,42], or zeolites [43,44]. It should also be noted that hydrazine decomposition can occur over other metals, such as rhodium [45], rhodium on alumina [46], Mo 2 N on γ -alumina [47], NbN x O y [48] and iron on MgO [49].…”

Section: Catalyst Modelsmentioning

confidence: 99%

The Decomposition of Hydrazine in the Gas Phase and over an Iridium Catalyst

Schmidt

Gordon

2013

Zeitschrift Für Physikalische Chemie

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Hydrazine / Gas Phase / Ir Catalyst / Quantum ChemistryHydrazine is an important rocket fuel, used as both a monopropellant and a bipropellant. This paper presents theoretical results to complement the extensive experimental studies of the gas phase and Ir catalyzed decompositions involved in the monopropellant applications of hydrazine. Gas phase electronic structure theory calculations that include electron correlation predict that numerous molecular and free radical reactions occur within the same energy range as the basic free radical pathways: NN bond breaking around 65 kcal/mol and NH bond breaking around 81 kcal/mol. The data suggest that a revision to existing kinetics modeling is desirable, based on the energetics and the new elementary steps reported herein. A supported Ir 6 octahedron model for the Shell 405 Iridium catalyst used in thrusters was developed. Self-Consistent Field and electron correlation calculations (with core potentials and associated basis sets) find a rich chemistry for hydrazine on this catalyst model. The model catalyst provides dramatically lower NN and NH bond cleavage energies and an even smaller barrier to breaking the NH bond by NH 2 abstractions. Thus, the low temperature decomposition over the catalyst is interpreted in terms of consecutive NH 2 abstractions to produce ammonia and nitrogen. The higher temperature channel, which has hydrogen and nitrogen products, may be due to a mixture of two mechanisms. These two mechanisms are successive NH cleavages with surface H + H recombinations, and the same type of assisted H 2 eliminations found to occur in the gas phase part of this study.

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