Hydrazine Decomposition Reaction Research Articles

Au Based Ni and Co Bimetallic Core Shell Nanocatalysts for Room Temperature Selective Decomposition of Hydrous Hydrazine to Hydrogen

AbstractNickel and Cobalt bimetallic catalysts with Au as core metal has been synthesized and demonstrated for hydrazine decomposition reaction for producing hydrogen. Gold‐cobalt and gold nickel bimetallic system belonging to the class of strained structures with high lattice mismatch of approximately 14% are demonstrated for synergistic effects atypical of monometallic counterparts for the selective decomposition of hydrous hydrazine to H2 with N2 as the other product at room temperature.

In situ synthesis of Ni nanofibers via vacuum thermal reduction and their efficient catalytic properties for hydrogen generation

Ni nanofibers have been prepared by a vacuum thermal reduction method, and further used as efficient catalysts for hydrogen generation from hydrous hydrazine decomposition reaction.

Problems of microthruster development

A description of a microthruster operating on the single-component propellant-hydrazine with the Shell-405 catalyst is presented. The hydrazine decomposition reaction at the specified parameters occurs on the surface. The gas temperature entering the nozzle actually depends on the catalyst temperature. It is established that if the temperature of hydrazine decomposition products at the catalyst outlet is lower than 400 K, ammonia condensation takes place in the supersonic nozzle part. The temperature distribution in the working chamber microchannel is calculated, the microthruster thrust and specific impulse are evaluated on the basis of a physico-mathematical model. A fundamental possibility of obtaining 10−3−10−2 N level thrust is shown.

Facile synthesis of mesoporous N doped zirconium titanium mixed oxide nanomaterial with enhanced photocatalytic activity under visible light

The present paper deals with a hydrazine mediated synthesis of high surface area and thermally stable N-doped zirconium titanium mixed oxide with enhanced photocatalytic activity towards reduction of selenium (VI) to metallic Se0 under visible light. Materials were synthesized at pH = 2 by varying the hydrazine concentration and characterized by XRD, TEM, BET method, XPS, Raman spectroscopy and UV-vis solid state spectra. Presence of low amount of zirconium oxide (10 wt%) helps in phase stabilization and maintains the porous structure even at higher calcinations temperature in comparison to that of pure titania. XPS spectrum justifies the presence of nitrogen and Ti3+ in the material due to the decomposition reaction of hydrazine. Hydrazine controls the nitrogen content, surface area and the formation of oxygen vacancy in the material. Investigation of metal oxide to hydrazine ratio on the overall surface properties and photocatalytic activity indicates that the 1 : 6 ratio is the optimum composition for the best result. Surface area and pore volume increases to 298 m2/g and 0.323 cm3/g. The obtained material (TiZr-6N-400) is found to reduce selenium (VI) to selenium (0) under visible light within only 45 min of reaction. Increased photocatalytic activity under visible light is mostly due to the synergistic effect of substantial nitrogen doping, high surface area and presence of oxygen vacancy.

Catalytic Performance of Activated Carbon Supported Tungsten Carbide for Hydrazine Decomposition

Activated carbon (AC) supported tungsten carbide was reported for the catalytic decomposition of hydrazine for the first time. It was found that the WC x /AC-H catalyst prepared by a carbothermal hydrogen reduction process exhibited excellent catalytic performances both in the microreactor and in a 1 Newton hydrazine microthruster. The XRD, TEM and microcalorimetry results suggest that the formation of well crystallized W2C phase, the restraining of the carbon deposition, as well as the prohibiting of the methanation should be responsible for the high activity and stability of the WC x /AC-H catalyst in the hydrazine decomposition reaction.

06/01142 A novel approach for CO-free H 2 production via catalytic decomposition of hydrazine : Zheng, M. et al. International Journal of Hydrogen Energy, 2005, 30, (10), 1081–1089

The aim of this work is to employ niobium oxynitride with macropores generation in the hydrazine decomposition reaction as substitute of iridium supported catalysts used for space communication satellites, which are equipped with microthrusters that control their orbit and attitude. The performance of niobium oxynitride was compared to tungsten oxynitride and Shell 405 catalyst.

Microcalorimetric studies of the iridium catalyst for hydrazine decomposition reaction

Microcalorimetric studies of H 2, NH 3 and O 2 adsorption, as well as the NH 3 decomposition activities evaluation were used to characterize the iridium catalysts for hydrazine decomposition with different supports (Al 2O 3, SiO 2) and iridium contents (1.8, 10.8 and 22.1%). The higher H 2 chemisorption amounts on Ir/Al 2O 3 catalysts than those on the corresponding Ir/SiO 2 counterparts revealed that the strong interaction of iridium and Al 2O 3 led to higher dispersion of iridium on Ir/Al 2O 3 catalysts than on Ir/SiO 2 catalysts. The larger increase in strong H 2 adsorption sites on highly loaded Ir/Al 2O 3 than the corresponding Ir/SiO 2 ones could be attributed to the interaction not only between iridium atoms but also between iridium and Al 2O 3. The microcalorimetric results for NH 3 adsorption showed that no apparent chemisorption of NH 3 existed on Ir/SiO 2 catalysts while NH 3 chemisorption amounts increased on Ir/Al 2O 3 catalysts with iridium loadings, which arose from the interaction of the catalysts support of Al 2O 3 with chloride anion. Both highly dispersed iridium active sites and chloride anion on Ir/Al 2O 3 catalysts could be beneficial to the intermediate NH 3 decomposition in N 2H 4 decomposition. The similar O 2 plots of differential heat versus normalized coverage on Ir/Al 2O 3 and Ir/SiO 2 catalysts could not be due to the metal–support interaction, but to the formation of strong Ir O bond.

Novos materiais à base de nanofibras de carbono como suporte de catalisador na decomposição da hidrazina

Today satellites propulsion is based on the use of monopropellant and/or bipropellant chemical systems. The maneuvering of satellite is based on the hydrazine decomposition micropropulsors catalyzed by metallic iridium supported on g-alumina. This reaction is a surface reaction and is strongly exothermic and implies that the operation of the micropropulsor is controlled by the mass and heat diffusions. For this reason and for the fact that the propulsor operation is frequently in pulsed regime, the catalyst should support high pressure and temperature variations within a short time period. The performance and the durability of the commercial catalyst are jeopardized by the low thermal conductivity of the alumina. The low thermal conductivity of the alumina support restricts the heat diffusion and leads to the formation of hot spots on the catalyst surface causing the metal sintering and/or fractures of the support, resulting in loss of the activity and catalyst destruction. This work presents the synthesis and characterization of new carbon composite support for the active element iridium, in substitution of the commercial catalysts alumina based support. These supports are constituted of carbon nanofibers (30 to 40 nm diameter) supported on a macroscopic carbon felt. These materials present high thermal conductivity and mechanical resistance, as well as the easiness to be shaped with different macroscopic shapes. The mechanical stability and the performance of the iridium supported on the carbon composite support, evaluated in a laboratory scale test in hydrazine decomposition reaction, are superior compared to the commercial catalyst.

Effect of anode electrocatalyst for direct hydrazine fuel cell using proton exchange membrane

Abstract Hydrazine was examined as a fuel in a direct-liquid-fueled fuel cell that uses proton exchange membrane (PEM) such as Nafion®. Different kinds of noble metals were examined as anode electrocatalysts for direct hydrazine fuel cells (DHFCs). In DHFC using platinum or palladium as the anode electrocatalyst, more than 1 V of cell voltage was obtained in the low-current density region. The I–V characteristics changed drastically depending on the kind of anode electrocatalyst used. Compositions of the exhaust materials from each electrode were analyzed to investigate the reaction occurring at the electrodes. The analysis revealed that the catalytic decomposition reaction of hydrazine proceeded further than the electro-oxidation reaction on the anode side using rhodium or ruthenium.

Investigation of PEM type direct hydrazine fuel cell

Hydrazine was examined as a fuel in a direct-liquid-fueled fuel cell employing proton exchange membrane (PEM) for the electrolyte. Hydrazine showed better performance than methanol in the direct fuel cell; the cell using hydrazine gave voltage twice as high as that using methanol in the low-current density region. The I– V characteristics were drastically changed depending on the surface area of the anode catalyst. Compositions of the exhaust materials from each electrode were analyzed in order to investigate the reaction that occurred at the electrodes. The analysis revealed that the catalytic decomposition reaction of hydrazine proceeded further than the electro-oxidation reaction on the anode side using a high specific surface area catalyst. The crossover of hydrazine and ammonia through the PEM was confirmed and the reduction of the hydrazine crossover is important in developing further high performance.

Catalytic Decomposition of Hydrazine on Tungsten Carbide: The Influence of Adsorbed Oxygen

Passivated and nonpassivated tungsten carbide (WC) powders were prepared by a temperature-programmed reaction and used as catalysts in the hydrazine decomposition reaction. All catalysts were active at 313 K. The only products of reaction were nitrogen and ammonia, suggesting that the reaction route and the rate-determining step were not modified by adsorbed oxygen. Surface oxygen atoms reacted with hydrazine, resulting in a larger decrease in the rate of reaction for the passivated solids. Excess carbon on the surface of the carbide inhibited the decomposition of hydrazine and resulted in a decrease of ca. 48% in the specific surface area of the tungsten carbide. The excess carbon may be removed in flowing hydrogen at 1000 K. When compared to commercial Ir catalyst (Shell 405), WC is less active in the hydrazine decomposition reaction.

Hydrazine decomposition over niobium oxynitride with macropores generation

The aim of this work is to employ niobium oxynitride with macropores generation in the hydrazine decomposition reaction as substitute of iridium supported catalysts used for space communication satellites, which are equipped with microthrusters that control their orbit and attitude. The performance of niobium oxynitride was compared to tungsten oxynitride and Shell 405 catalyst.

Transition metal catalysis of the heterogeneous decomposition of hydrazine: adiabatic kinetics by accelerating rate calorimetry

The thermochemical kinetics of the transition-metal-catalyzed decomposition reaction of hydrazine have been studied using accelerating rate calorimetry. The reaction stoichiometry was determined by both product analysis and thermochemical balance. In the range 350–515 K when both liquid and vapor hydrazine are present, the decomposition proceeds according to: N 2H 4(1)→ 1 3 N 2(g)+ 4 3 NH 3(g) with Δ H rxn = −123.3 kJ mol −1 (515 K). In the range 515–590 K when only vapor is present in the reaction system, Δ H rxn = −154.8 kJ mol −1 (515 K). The reaction shows apparent zero-order kinetics and the rates were found to be proportional to the surface area of added metals in the form of powders or foils. Rates and activation parameters are reported for ten transition metals and the Fe : Ni : Cr alloy, 304L stainless steel. The activation energies and relative specific activities at 353 K are: Co (43 kJ mol −1, 3900); Ni (93 kJ mol −1, 310); Mo (76 kJ mol −1, 94); V (85 kJ mol −1, 66); Fe (119 kJ mol −1, 33); W (68 kJ mol −1, 11); Au (74 kJ mol −1, 7.8); Ti (95 kJ mol −1, 1.0); 304L (100 kJ mol −1, 0.43); Cr (105 kJ mol −1, 0.099); Ta (106 kJ mol −1, 0.06). The Arrhenius activation parameters for the various metals (and different samples of the same metal) show a linear compensation effect: In A = (1/θ) E a/ R + 1n k o with a compensation temperature, θ, of 445 K. Different samples of molybdenum powders showed θ = 432 K and an isokinetic temperature of 430 K, at which the rates for all molybdenum samples were equal. The relative activities are explained in terms of the binding energies of N-adatoms to the metal surface and an empirical thermochemical relationship is proposed. Additionally it is noted that the least catalytically reactive metals are those whose ambient-atmosphere oxide films are not reduced by hydrazine.

Investigation on an electrothermal hydrazine thruster

Thermal decomposition of hydrazine can be achieved when the fluid propellant is sprayed on an electrically heated surface. After the exothermal hydrazine decomposition reaction has been triggered, the electrical heating may be reduced or stopped completely. Investigations are made using an experimental thruster at a thrust level of 100 mN to 500 mN to achieve advantageous power consumption and thruster behavior by means of an optimal adjustment of heater configuration and propellant distribution within the reactor. Uniform distribution of very small quantities of propellant over the heater surface is essential for good performance. Tests have been most successful when the propellant is sprayed on fine-meshed screen. Further tests have been made using metal foam for distributing the propellant over a large surface. The foam pack has been heated up by internal heater coils to initiate decomposition. Metal foam offers some advantages when especially low propellant mass flowrates are used, but suitable foam materials are not available at this time.