Hydroxylammonium nitrate or hydroxylamine nitrate (HAN) is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...

with the chemical formula H₃OHNO₃]. It is a salt derived from

hydroxylamine Hydroxylamine is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound.Greenwood and Earnshaw. ''Chemistry of the Elements.'' 2nd Edition. Reed Educational and Professional Publishing Ltd. pp. 431–43 ...

and

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...

. In its pure form, it is a colourless

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...

solid. It has potential to be used as a

rocket propellant Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemic ...

either as a solution in monopropellants or bipropellants. Hydroxylammonium nitrate (HAN)-based propellants are a viable and effective solution for future green propellant-based missions, as it offers 50% higher performance for a given propellant tank compared to commercially used

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...

Properties

The compound is a salt with separated hydroxyammonium and nitrate ions. Hydroxylammonium nitrate is unstable because it contains both a

reducing agent In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ). Examples of substances that are commonly reducing agents include the Earth met ...

(hydroxylammonium cation) and an

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

(

nitrate Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...

), the situation being analogous to

ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...

. It is usually handled as an aqueous solution. The solution is corrosive and toxic, and may be carcinogenic. Solid HAN is unstable, especially in the presence of trace amounts of metal salts.

Laboratory preparatory routes

# Catalytic reduction of nitric oxides # Double decomposition # Electrolysis # Hydrogenation of nitric acid # Ion exchange via resins # Neutralization

Applications

HAN has applications as a component of

, in both solid and liquid form. HAN and

ammonium dinitramide Ammonium dinitramide (ADN) is the ammonium salt of dinitraminic acid. ADN decomposes under heat to leave only nitrogen, oxygen, and water. The ions are the ammonium ion NH4+ and the dinitramide N(NO2)2−. It makes an excellent solid rocket oxi ...

(ADN), another energetic ionic compound, were investigated as less-toxic replacements for toxic

for

monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with bipro ...

rockets where only a catalyst is needed to cause decomposition. HAN and ADN will work as monopropellants in water solution, as well as when dissolved with fuel liquids such as

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...

. HAN is used by the

Network Centric Airborne Defense Element The Network Centric Airborne Defense Element (NCADE) is an anti-ballistic missile system being developed by Raytheon for the Missile Defense Agency. On Sept. 18, 2008 Raytheon announced it had been awarded a $10 million contract to continue NCADE re ...

boost-phase interceptor being developed by Raytheon. As a solid propellant oxidizer, it is typically bonded with glycidyl azide polymer (GAP),

hydroxyl-terminated polybutadiene Hydroxyl-terminated polybutadiene (HTPB) is an oligomer of butadiene terminated at each end with a hydroxyl functional group. It reacts with isocyanates to form polyurethane polymers. HTPB is a translucent liquid with a color similar to wax paper ...

(HTPB), or carboxy-terminated polybutadiene (CTPB) and requires preheating to 200-300 °C to decompose. When used as a monopropellant, the catalyst is a noble metal, similar to the other

s that use

silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...

palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself ...

, or

iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density o ...

. HAN also enabled the development of solid propellants that could be controlled electrically and switched on and off. Developed by DSSP for special effects and microthrusters, these were the first HAN-based propellants in space; and aboard the Naval Research Laboratory SpinSat, launched in 2014. It will be used in a fuel/oxidizer blend known as "AF-M315E" in the high thrust engines of the

Green Propellant Infusion Mission The Green Propellant Infusion Mission (GPIM) was a NASA technology demonstrator project that tested a less toxic and higher performance/efficiency chemical propellant for next-generation launch vehicles and CubeSat spacecraft. When compared ...

, which was initially expected to be launched in 2015, and eventually launched and deployed on 25 June 2019. The specific impulse of AF-M315E is 257 s. The aqueous solution of HAN can be added with fuel components such as methanol, glycine, TEAN (tri-ethanol-ammonium nitrate), and amines to form best high performance monopropellants for space propulsion systems.

China Aerospace Science and Technology Corporation The China Aerospace Science and Technology Corporation, or CASC, is the main contractor for the Chinese space program. It is state-owned and has subsidiaries which design, develop and manufacture a range of spacecraft, launch vehicles, strategi ...

(CASC) launched a demonstration of HAN-based thruster aboard a microsatellite in January 2018. Japanese technology demonstration satellite

Innovative Satellite Technology Demonstration-1 The Innovative Satellite Technology Demonstration Program is a series of spacecraft missions for testing technology and ideas put forward by universities and private companies. The program demonstrates various experimental devices and technology ...

, launched in January 2019, contains a demonstration thruster using HAN and operated successfully in orbit. HAN is sometimes used in

nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, th ...

as a reducing agent for plutonium ions.

Bibliography

*Donald G. Harlow et al. (1998). "Technical Report on Hydroxlyamine Nitrate". U.S. Department of Energy
DOE/EH-0555
*Gösta Bengtsson et al. (2002) "The kinetics and mechanism of oxidation of hydroxylamine by iron(III)". J. Chem. Soc., Dalton Trans., 2002, 2548–2552

References

{{Reflist, 30em Explosive chemicals Hydroxylammonium compounds Monopropellants Nitrates Rocket fuels