The reaction route and active site of catalytic decomposition of hydrazine over molybdenum nitride catalyst

Chen, Xiaowei; Zhang, Tao; Wu, Zili; Wu, Weicheng; Li, Can

doi:10.1016/j.jcat.2004.02.035

Cited by 109 publications

(65 citation statements)

References 20 publications

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“…Isoelectronic metal atoms occasionally exhibit the same catalysis as is exemplified by the nitration of alkylbenzenes catalyzed by Hg(II), Tl(III), or Pb(IV) (Figure 10) 3 ], and that these complexes catalyze the hydrogenation of olefinic bonds [30]. The carbides and nitrides of niobium, molybdenum, and tungsten exhibit similar catalysis to iridium metal for hydrazine decomposition in the thruster engines of satellites [31]. This has been explained by the addition of the ligand atomʼs valence electrons to the metal atoms, which affords an electron distribution similar to that of the iridium metal.…”

Section: Active Site Of Molybdenum Clustermentioning

confidence: 99%

Characterization of Catalytically Active Octahedral Metal Halide Cluster Complexes

Kamiguchi

Nagashima

Chihara

2014

Metals

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Abstract:Halide clusters have not been used as catalysts. Hexanuclear molecular halide clusters of niobium, tantalum, molybdenum, and tungsten possessing an octahedral metal framework are chosen as catalyst precursors. The prepared clusters have no metal-metal multiple bonds or coordinatively unsaturated sites and therefore required activation. In a hydrogen or helium stream, the clusters are treated at increasingly higher temperatures. Above 150-250 °C, catalytically active sites develop, and the cluster framework is retained up to 350-450 °C. One of the active sites is a Brønsted acid resulting from a hydroxo ligand that is produced by the elimination of hydrogen halide from the halogen and aqua ligands. The other active site is a coordinatively unsaturated metal, which can be isoelectronic with the platinum group metals by taking two or more electrons from the halogen ligands. In the case of the rhenium chloride cluster Re 3 Cl 9 , the cluster framework is stable at least up to 300 °C under inert atmosphere; however, it is reduced to metallic rhenium at 250-300 °C under hydrogen. The activated clusters are characterized by X-ray diffraction analyses, Raman spectrometry, extended X-ray absorption fine structure analysis, thermogravimetry-differential thermal analysis, infrared spectrometry, acid titration with Hammett indicators, and elemental analyses. OPEN ACCESSMetals 2014, 4 85 Keywords: niobium and tantalum; molybdenum and tungsten; rhenium; chloride and bromide; inorganic cluster complex; Brønsted acid; coordinatively unsaturated site; bi-functional catalyst

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Section: Active Site Of Molybdenum Clustermentioning

confidence: 99%

Characterization of Catalytically Active Octahedral Metal Halide Cluster Complexes

Kamiguchi

Nagashima

Chihara

2014

Metals

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“…Because iridium is rare and expensive, great effort is made to search for feasible high-performance substitutes for iridium catalysts [4,5,[22][23][24][25][26][27][28][29][30]. However, none of them show better total performance than the conventional iridium catalyst.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory investigations on the catalytic mechanisms of hydrazine decompositions on Ir(111)

et al. 2011

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“…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]. Reactivity of course depends on the reacting species, the metal, its particle size, and the support, with Shell 405 being particularly effective for hydrazine decomposition.…”

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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The reaction route and active site of catalytic decomposition of hydrazine over molybdenum nitride catalyst

Cited by 109 publications

References 20 publications

Characterization of Catalytically Active Octahedral Metal Halide Cluster Complexes

Characterization of Catalytically Active Octahedral Metal Halide Cluster Complexes

Density functional theory investigations on the catalytic mechanisms of hydrazine decompositions on Ir(111)

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

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