Macroporous–mesoporous alumina supported iridium catalyst for hydrazine decomposition

Explosive thermal reduction of graphene oxide-based materials: Mechanism and safety implications

“…In other known energetic materials, thermal runaway reactions occur when decomposition reaction heat cannot be dissipated fast enough to the surroundings, and local temperatures within the sample rise. Decomposition reactions have significant activation energies, and the elevated local temperatures thus cause accelerated decomposition rates and further heating in uncontrolled fashion leading to rapid gas release and pressure waves associated with deflagration or detonation mechanisms [17]. The stability of energetic materials is typically mass dependent, as the rate of heat generation is proportional to L 3 (for 3D bodies), while heat loss is related to surface area (~L 2 ) and size dependent heat transfer coefficients.…”

“…The thermal runaway reaction is caused by the exothermicity of GO decomposition (~ 1600 Jg −1 ) coupled with heat and mass transfer limitations that become more severe with increasing sample mass. Table 2 shows that GO mass-specific enthalpy of decomposition associated with its thermal reduction is comparable with the decomposition enthalpies of known explosives or monopropellants such as hydrazine [17], trinitrotoluene (TNT) [18], nitrocellulose [19] and hazardous industrial chemicals such as cumene hydroperoxide [21], benzoyl peroxide [22]. The micro-explosions observed here occur for sample masses as low as few milligrams and can damage laboratory equipment, but a potentially more significant concern is the large-scale storage, handling, and processing of bulk graphene oxide as GO-based technologies are piloted and commercialized.…”

“…We hypothesized that the self-initiating rapid reduction of GO with large-volume gas release would show features in common with other energetic materials (explosives and mono-propellants) [17–19] and of some reactive chemicals that represent important safety concerns in industry [20–22], and must be understood and characterized for the safe handling of GO, especially at large scale. In the present study, we observe explosive decomposition during the thermal reduction of GO in inert gas environments leading to laboratory equipment damage, which occurs for some GO samples, but not others.…”

NiIr Nanoparticles Immobilized on the Pores of MIL-101 as Highly Efficient Catalyst toward Hydrogen Generation from Hydrous Hydrazine

“…For example, Cho et al reported a set amount of Ir-based catalysts, prepared at high temperatures (>400°C), and the decomposition of hydrazine were tested at high pressures (i.e., 350 psi). 42 44 Zhang's group reported a two-step synthesis of a NiIr/Al 2 O 3 catalyst by reducing the precursor in the H 2 atmosphere at 500°C to get Ni/Al 2 O 3 first, and further reducing in the H 2 atmosphere at 300°C after being mixed with H 2 IrCl 6 . This catalyst exhibits a turnover frequency (TOF) value of 6.3 h −1 with 99% H 2 selectivity at 30°C.…”

Ir Impregnation on Alumina Pores: Catalyst Activity and Loss During Hydrazine Decomposition

“…Reaction (1) is a highly exothermic reaction which could cause a temperature increase of up to 1273 K . The resulting high temperatures could have a significant effect on the structural properties of the catalyst and lead to a decrease in its activity . Since the catalytic reactor is the heart of the space thruster, any decrease or drawback in the catalytic activity can directly influence the thruster operation and decrease its lifetime.…”