Decomposition of Hydroxylammonium Nitrate Solution Over Nanoporous CuO Supported on Honeycomb.

We investigated the influence of a copper loading strategy over a honeycomb structure on the catalytic performance during the decomposition of a hydroxylammonium nitrate (HAN) aqueous solution. Copper was supported on the honeycomb surface by means of a metal coating method (MC), i.e., a method of directly coating a metal, and a metal alumina coating method (MAC), i.e., a method of coating a mixture of metal and alumina. The properties of the catalysts were analyzed by N2 adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Cu(16.8)/honeycomb-MC catalyst showed a lower decomposition onset temperature during the decomposition of the HAN aqueous solution compared to that over the Cu(7.0)/honeycomb- MAC catalyst, an outcome ascribed to the higher copper loading and the higher dispersion of copper in the Cu(16.8)/honeycomb-MC catalyst compared to that in the other catalyst. The Cu(16.8)/honeycomb-MC catalyst was confirmed to have both excellent activity and heat resistance during the decomposition of a HAN aqueous solution.

Catalytic Decomposition of Energetic Liquid Solution Over Various Types of Hexaaluminate Catalysts.

A hexaaluminate support was prepared by a co-precipitation method, and a metal (Cu, Pt, or Ir) was impregnated on the support to prepare a powdered catalyst. After that, organic and inorganic binders were added to the powdery catalyst and then pellets were formed. The so-formed catalysts were heat-treated at 1200°C, and their physicochemical properties were analyzed by N2-adsorption, X-ray diffraction (XRD), X-ray fluorenscence (XRF), and scanning electron microscopy (SEM). The decomposition activity of the catalysts on an ammonium dinitramide (ADN)-based liquid propellant was evaluated repeatedly, and the effects of catalyst composition and morphology on low temperature decomposition activity and durability were investigated. It was confirmed that the Cu-hexa-pellet, Pt-hexa-pellet, and Ir-hexa-pellet catalysts could be recovered and reused as a catalyst for decomposition of an ADN-based liquid monopropellant. The initial activity and the thermal stability of the Cu-hexa-pellet catalyst for the decomposition of ADN-based liquid monopropellants were better than for the other catalysts. The better activity of the Cu-hexa-pellet catalyst seems to be because the dispersion of the copper was higher than the metal dispersion in the other two catalysts.

Decomposition of Ionic Liquid Solution Over CuIr-Hexaaluminate Catalysts.

The objective of this study is to elucidate the catalytic performance of hexaaluminate catalysts incorporating Cu and Ir simultaneously during the decomposition of an ammonium dinitramide (ADN)-based liquid propellant. Pellet-type catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, and XRF. It was confirmed that Cu and Ir atoms are well incorporated inside the hexaaluminate matrix of the Cu(x)Ir(10-x)-hexaaluminate catalysts and the content of Ir incorporated into hexaaluminte matrix was in the range of 2.5-8.2 wt%. The Cu(7)Ir(3)-hexaaluminate catalyst showed excellent activity in decomposition of ADN-based liquid monopropellant. The activity of the Cu(7)Ir(3)-hexaaluminate catalyst was much higher than that of the Cu(7)Ir(3)/hexaaluminate-imp catalyst prepared by impregnation of Cu and Ir onto the hexaaluminate pellet surface. This is attributed to the Cu and Ir being well incorporated in the hexaaluminate matrix and the dispersion of the Cu and Ir being greater in the Cu(7)Ir(3)-hexaaluminate than in the Cu(7)Ir(3)/hexaaluminate-imp.

Catalytic Decomposition of an Ionic Liquid Monopropellant Over Ir/Hexaaluminate Catalysts.

The aim of this study is to elucidate the influence of an iridium loading strategy over hexaaluminate on the catalytic performance during the decomposition of liquid monopropellants based on ammonium dinitramide (ADN). Powder-type and pellet-type Ir/hexaaluminate catalysts were prepared and their chemico-physical properties were characterized by N2 adsorption, XRD, XRF, and SEM. There were considerable differences in the Ir amounts present on the surface according to the impregnation method employed. The catalytic activities of three types of Ir/hexaaluminate catalysts to decompose the ADN-based liquid monopropellant were compared using a semi-batch type of reactor. Pellet-type Ir/hexaaluminate catalyst, which formed hexaaluminate into a pellet and where iridium was impregnated during the last stage, showed the lowest onset temperature during the decomposition of the ADN-based liquid monopropellant, having the effect of lowering the decomposition onset temperature by around 60 °C compared to that without a catalyst. This was due to the pellet-type Ir/hexaaluminate having a larger surface area and a large number of Ir active sites on its surface.