Patent Application
20220024836
Hydrazines are used as rocket propellants and industrial solvents. However, hydrazines generally have a high vapor toxicity, and handling precautions must therefore be taken for safety purposes. Hydrazines have been combined with additives to modify properties such as freezing point, gelling, or propulsive performance. While there has been success in modifying certain properties, efforts have largely failed to reduce vapor toxicity without significantly debiting desirable functional characteristics, such as catalytic behavior and solvent strength.
A hydrazine-containing composition according to an example of the present disclosure includes a liquid mixture that has from 5 mol % to 95 mol % of unprotonated hydrazine selected from a group consisting of hydrazine, monomoethylhydrazine, dimethylhydrazine, ethylhydrazine, and combinations thereof, the unprotonated hydrazine having a first vapor pressure, and from 5 mol % to 90 mol % of at least one oxygen-containing solute or solvent having a second vapor pressure that is less than the first vapor pressure. The at least one oxygen-containing solute or solvent is selected from the group consisting of acetals, acetyls, alcoxyamines having two or more carbon atoms, aldehydes, amides, aminoalcohols, carbazides, semicarbazides, carbon-containing nitrate salts including cations with logarithmic dissociation constants greater than 9.2, hydroxyalkyl nitro compounds, hydroxyalkylhydrazines, carbonates, carboxylic acids and anhydrides of carboxylic acids, esters, ethers, ketals, ketones, mono- and poly-alcohols in 31% or greater mass fraction, nitrate esters, nitrosamines, sugars, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the at least one oxygen-containing solute or solvent is selected from a group consisting of carbohydrazide nitrate, ethylammonium nitrate, ethylene dihydrazine nitrate, hydroxyethylhydrazine, hydroxyethylhydrazinium nitrate, bis(2-hydroxyethyl)hydrazine, bis(2-hydroxyethyl) hydrazinium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes up to 98 mol % water.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes an oxidizer selected from a group consisting of ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, hydroxylammonium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the at least one oxygen-containing solute or solvent is selected from a group consisting of ethylammonium nitrate, hydroxyethylhydrazinium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes up to 98 mol % of water.
In a further embodiment of any of the foregoing embodiments, in the liquid mixture includes an oxidizer selected from a group consisting of ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, hydroxylammonium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the at least one oxygen-containing solute or solvent is ethylammonium nitrate.
In a further embodiment of any of the foregoing embodiments, the at least one oxygen-containing solute or solvent is hydroxyethylhydrazinium nitrate.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes up to 98 mol % of water.
In a further embodiment of any of the foregoing embodiments, in the liquid mixture includes an oxidizer.
In a further embodiment of any of the foregoing embodiments, the oxidizer is selected from a group consisting of ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, hydroxylammonium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the oxidizer is hydrazinium nitrate.
In a further embodiment of any of the foregoing embodiments, the at least one oxygen-containing solute or solvent is selected from a group consisting of carbohydrazide nitrate, ethylammonium nitrate, ethylene dihydrazine nitrate, hydroxyethylhydrazine, hydroxyethylhydrazinium nitrate, bis(2-hydroxyethyl)hydrazine, bis(2-hydroxyethyl)hydrazinium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes up to 98% of water.
In a further embodiment of any of the foregoing embodiments, the liquid mixture has a density of 1.1 grams per cubic centimeter to 1.5 grams per cubic centimeter.
In a further embodiment of any of the foregoing embodiments, the second vapor pressure is less than the first vapor pressure by at least 50%.
A hydrazine-containing composition according to an example of the present disclosure includes a liquid mixture including water, an oxidizer selected from the group consisting of ammonium dinitramide, ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, hydroxylammonium nitrate, and combinations thereof, unprotonated hydrazine selected from the group consisting of hydrazine, monomoethylhydrazine, dimethylhydrazine, ethylhydrazine, and combinations thereof, and at least one oxygen-containing solute or solvent selected from the group consisting of carbohydrazide nitrate, ethylammonium nitrate, ethylene dihydrazine nitrate, hydroxyethylhydrazine, hydroxyethylhydrazinium nitrate, and combinations thereof.
In a further embodiment of any of the foregoing embodiments, the liquid mixture includes 20 mol % to 80 mol % of the unprotonated hydrazine, 10 mol % to 80 mol % of the oxygen-containing solute or solvent, 0 mol % to 20 mol % of the oxidizer, and 0 mol % to 20 mol % of the water.
In a further embodiment of any of the foregoing embodiments, the oxidizer is hydrazinium nitrate, and the at least one oxygen-containing solute or solvent is selected a group consisting of ethylammonium nitrate and hydroxyethylhydrazinium nitrate, and combinations thereof.
Disclosed herein is a low-vapor toxicity liquid hydrazine composition that maintains good performance as a rocket propellant and industrial solvent. Additives have previously been used in combination with hydrazine. However, such additives have not effectively diminished the vapor-toxicity of hydrazines to levels safe for human exposure without also destroying the desirable properties of hydrazine. For instance, such additives often render the mixture to be too dilute or viscous, reduce the chemical activity to ineffective levels, or reduce the storage life to unacceptable levels.
It has now unexpectedly been found, however, that certain oxygen-containing solutes and solvents effectively lower the vapor toxicity of hydrazine while maintaining the functional aspects of hydrazine that make it attractive for use as a rocket propellant or industrial solvent. For instance, strong oxygen-containing solutes and solvents that form azeotropic and/or pseudoazeotropic mixtures with hydrazine and that have lower vapor pressure than hydrazine can be mixed with hydrazine to effectively lower the vapor toxicity while maintaining functionality.
The hydrazine-containing composition is a liquid mixture and includes from 5 mol % to 90 mol % hydrazine selected from hydrazine, monomethylhydrazine, dimethylhydrazine, ethylhydrazine, and combinations thereof, and from 5 mol % to 95 mol % of at least one oxygen-containing solute or solvent selected from acetals, acetyls, alcoxyamines having two or more carbon atoms, aldehydes, amides and particularly carboxamides, aminoalcohols, carbazides and semicarbazides, carbon-containing nitrate salts comprising cations with logarithmic dissociation constants greater than 9.2, hydroxyalkyl nitro compounds, hydroxyalkylhydrazines, carbonates, carboxylic acids and anhydrides of carboxylic acids, esters, ethers, ketals, ketones, mono- and poly-alcohols in 31% or greater mass fraction, nitrate esters, nitrosamines, sugars, and combinations thereof.
The unprotonated hydrazine has a first vapor pressure and the oxygen-containing solute or solvent has a second vapor pressure that is less than the first vapor pressure. Vapor pressure is typically expressed in units of millimeters Hg at a reference temperature of 25° C., but any equivalent units could be used. Lower vapor pressure solute or solvents are preferred, in that the resulting reduction in the hydrazine vapor pressure and vapor toxicity will be generally greater. For instance, a liquid mixture where the second vapor pressure is 90% less than the first vapor pressure will reduce the hydrazine vapor toxicity more than one of equal molar proportions of the hydrazine and solute or solvent where the second vapor pressure is 30% less than the first vapor pressure, where the units of comparison are millimeters Hg at a reference temperature of 25° C. In one example, the second vapor pressure is less than the first vapor pressure by at least 50%.
The unprotonated hydrazine is substantially unprotonated in the liquid mixture. For instance, the oxygen-containing solute or solvent is nonacidic or of basic pH so as to minimize protonization of the hydrazine. In turn, the unprotonization of the hydrazine serves to preserve the catalytic and chemical activity of the hydrazine rather than altering these activities as do other, more acidic, additives.
Example solutes and solvents suitable for use in the liquid mixtures of the present invention are listed as follows:
The liquid mixture also preferably has a relatively high density, which is desirable for good density-specific impulse performance. As an example, the liquid mixture has a preferred density of at least 1.1 grams per cubic centimeter, and most preferably greater than 1.25 grams per cubic centimeter. In one example, the liquid mixture has a density of 1.1 grams per cubic centimeter to 1.5 grams per cubic centimeter.
In further examples, the oxygen-containing solute or solvent is selected from carbohydrazide nitrate, ethylammonium nitrate, ethylene dihydrazine nitrate, hydroxyethylhydrazine, hydroxyethylhydrazinium nitrate, and combinations thereof.
The liquid mixture of the examples above may also contain additional additives, such as other solutes or solvents and/or oxidizer. For instance, the liquid mixture includes up to 98 mol % of water. In another example, the liquid mixture includes an oxidizer selected from ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, hydroxylammonium nitrate, and combinations thereof. The liquid mixture may include the oxidizer at down to 0.5 equivalence ratio.
In a further example, the a liquid mixture includes water, an oxidizer selected from ammonium nitrate, carbohydrazide nitrate, hydrazinium nitrate, carbohydrazide nitrate, and combinations thereof, an unprotonated hydrazine selected from hydrazine, monomoethylhydrazine, dimethylhydrazine, ethylhydrazine, and combinations thereof, and an oxygen-containing solute or solvent selected from carbohydrazide nitrate, ethylammonium nitrate, ethylene dihydrazine nitrate, hydroxyethylhydrazine, hydroxyethylhydrazinium nitrate, and combinations thereof. For instance, the liquid mixture includes:
20 mol % to 80 mol % of the unprotonated hydrazine,
10 mol % to 80 mol % of the oxygen-containing solute or solvent,
0 mol % to 20 mol % of the oxidizer, and
0 mol % to 20 mol % of the water.
The liquid mixtures herein generally have a density of 25% to 30% greater than hydrazine alone and a vapor toxicity (vapor pressure) that is 5% to 0.01% of hydrazine alone. Additionally, the liquid mixtures herein can be used under the same catalytic preheat conditions for rocket propellants as hydrazine and can be used with known nickel superalloy thruster designs (i.e., the liquid mixtures do not require use of high-cost refractory thrusters). The following compositions demonstrate further examples of the liquid mixture.
70 mol % of hydrazine (N2H4),
30 mol % of hydroxyethylhydrazinium nitrate
Vapor pressure relative to neat hydrazine: 4%
Specific Impulse: 230 seconds
Density 1.24 g/cc
Reaction temperature: 910° C.
Viscosity: Approximately 13 cP at 20° C.
65 mol % of hydrazine (N2H4),
25 mol % of hydroxyethylhydrazinium nitrate
10 mol % hydrazinium nitrate
Vapor pressure relative to neat hydrazine: 0.4%
Specific Impulse: 235 seconds
Density 1.28 g/cc
Reaction temperature: 1100° C.
Viscosity: Approximately 10 cP at 20° C.
40 mol % of hydrazine (N2H4),
40 mol % of hydroxyethylhydrazinium nitrate
12 mol % hydrazinium nitrate
8 mol % of water
Vapor pressure relative to neat hydrazine: 0.04%
Specific Impulse: 235 seconds
Density 1.35 g/cc
Reaction temperature: 1100° C.
Viscosity: Approximately 31 cP at 20° C. Example 3:
35.7 mol % of hydrazine (N2H4),
35.7 mol % of ethylammonium nitrate
21.5 mol % hydrazinium nitrate
7.1 mol % of water
Vapor pressure relative to neat hydrazine: 0.03%
Specific Impulse: 235 seconds
Density 1.29 g/cc
Reaction temperature: 1100° C.
Viscosity: Approximately 11 cP at 20° C.
65 mol % of hydrazine (N2H4),
16 mol % of hydroxyethylhydrazinium nitrate
6.5 mol % ethylammonium nitrate
12.5 mol % hydrazinium nitrate
Vapor pressure relative to neat hydrazine: 0.4%
Specific Impulse: 235 seconds
51 mol % of hydrazine (N2H4),
23 mol % of ethylenedihydrazine nitrate
8 mol % hydrazinium nitrate
18 mol % of water
Vapor pressure relative to neat hydrazine: 0.3%
Specific Impulse: 235 seconds
Density 1.21 g/cc
Reaction temperature: 1040° C.
Viscosity: Approximately 16 cP at 20° C.
56 mol % of hydrazine (N2H4),
18 mol % of carbohydrazide
24 mol % carbohydrazide nitrate
2 mol % of water
Vapor pressure relative to neat hydrazine: 0.2%
Specific Impulse: 232 seconds
Density 1.36 g/cc
Reaction temperature: 1140° C.
Viscosity: Approximately 24 cP at 20° C.
51 mol % of hydrazine (N2H4),
22 mol % ethylammonium nitrate
23 mol % ammonium nitrate
4 mol % of water
Vapor pressure relative to neat hydrazine: 0.3%
Specific Impulse: 235 seconds
Density 1.27 g/cc
Reaction temperature: 1120° C.
Viscosity: Approximately 7 cP at 20° C.
70 mol % of momomethylhydrazine,
20 mol % of hydroxyethylhydrazinium nitrate
10 mol % ammonium nitrate
Vapor pressure relative to neat monomethylhydrazine: 1%
Specific Impulse: 205 seconds
Density 1.18 g/cc
Reaction temperature: 760° C.
Viscosity: Approximately 6 cP at 20° C.
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/014900 | 1/24/2019 | WO | 00 |
