USOO6328831B1 (12) United States Patent (10) Patent No.: US 6,328,831 B1 Wagaman (45) Date of Patent: Dec. 11, 2001

(54) GAS-GENERATING LIQUID 6,179,937 * 1/2001 Leveritt et al...... 149/45 COMPOSITIONS (PERHAN) OTHER PUBLICATIONS (75) Inventor: Kerry L. Wagaman, Bryantown, MD Anderson, W., et al. Low Cost Propulsion Using a High (US) Density, Storable, and Clean Propellant Combination. Mul, et al. Search For New Storable High Performance (73) Assignee: The United States of America as Propellants, (AIAA-88-3354, AIAA/ASME/SAE/ASEE represented by the Secretary of the 24th Joint Propulsion Conference, Boston, Jul. 1988. Navy, Washington, DC (US) Rusek, J., New Decomposition Catalysts And Characteriza (*) Notice: Subject to any disclaimer, the term of this tion Techniques For Rocket-Grade Hydrogen Peroxide J. of patent is extended or adjusted under 35 Propulsion and Power, 1996, 12,574–579. A document entitled Advanced Chemical Propulsion Sys U.S.C. 154(b) by 0 days. tems dated Nov. 21, 1995. Berezovsky, Pyrogen Fire Suppression System-Marine & (21) Appl. No.: 09/447,271 Vehicle Applications Dated Aug. 1997. (22) Filed: Nov. 23, 1999 Thomas, Martin, Fire Research News 20. (51) Int. Cl...... C06B 31/00 * cited by examiner (52) U.S. Cl...... 149/45 Primary Examiner Michael J. Carone (58) Field of Search ...... 149/45-108.8 ASSistant Examiner Aileen J. Baker (56) References Cited (74) Attorney, Agent, or Firm Mark Homer U.S. PATENT DOCUMENTS (57) ABSTRACT H1768 1/1999 Mueller et al. . A family of water-based, gas-generating liquid compositions 3,145,082 8/1964 Rausch et al...... 423/275 is described. A composition of the present invention 3,561,533 2/1971 McKinnell. includes: hydrogen peroxide, hydroxylammonium , 3,790,415 2/1974 Tomic . and water. Compositions of the present invention may be 4,047,988 9/1977 Weill et al.. mixed with fuels to make monopropellants or used in 4,527,389 * 7/1985 Biddle et al...... 60/207 bipropellant or hybrid Systems. Alternate uses of the present 5,607,181 3/1997 Richardson et al. . invention include breathable gas generation or use as an 5,648,052 7/1997 Schaefer et al...... 422/305 5,703,323 * 12/1997 Rothgery et al...... 149/88 oxygen Source in welding. 6,013,143 * 1/2000 Thompson ...... 149/1 6,098,516 8/2000 Gazonas ...... 86/20.15 22 Claims, 2 Drawing Sheets

Freezing Points for PERHAN Formulations H2O2= 100.0

Freezing Point -60.O -50.0 WATER=O.O ------40.0

-50.0 -2O.O - - - - - 10.0 O.O

HAN=1 OO.O WATER= 1 OO.O

U.S. Patent Dec. 11, 2001 Sheet 2 of 2 US 6,328,831 B1

SUIO!QeInULIJOJINIVH?IGIAIJOS????SUI3OI 3–0IJI US 6,328,831 B1 1 2 GAS-GENERATING LIQUID Gas-generating Systems in other applications also have COMPOSITIONS (PERHAN) problems associated with them. For example, chlorate-based "chlorate candle' oxygen BACKGROUND OF THE INVENTION generators are used for emergency breathable oxygen in 1. Field of the Invention Some airplanes and in welding applications. Because of the Solid nature of the Sodium chlorate, many of these devices The present invention relates to energetic and gas cannot be turned off once triggered, and the heat production generating compositions, and in particular to oxidizing from Such a device can prove to be a fire hazard. A compositions. liquid-based oxygen generator might overcome this prob 2. Description of the Related Art lem. Moreover, chlorate-based devices typically produce There are numerous applications for gas-generating com Some byproduct chlorine, which is toxic, in the breathable positions. Energetic gas-generating compositions are com gas, and do not produce any diluent for the generated monly used, for example, in rocket propulsion Systems as OXygen. well as torpedos, Safety air bags, etc. Oxygen-generating Examples of liquid gas-generating and explosive compo compositions also have utility in breathable air generators 15 Sitions of the contemporary art are seen in the following U.S. and underwater welding. Patents. U.S. Pat. No. 3,561,533, to McKinnell, entitled Of particular interest among these compositions are those Controlled Chemical Heating OF A Well Using Aqueous which are liquids, in particular liquids which are oxidizers. Gas-In-Liquid Foams, describes a two-component hyper Liquids are necessary for many propulsion Systems since golic reaction System in which an aqueous foam of hydra they can be pumped, and liquids are in general easier to Zine or dimethylhydrazine and an aqueous foam of hydrogen handle and Store than Solids. The most commonly used peroxide are mixed. The System is used to heat oil wells. liquid oxidizers for rocket propulsion have generally been U.S. Pat. No. 3,790,415, to Tomic, entitled Chemical liquid oxygen (LOX), inhibited red fuming Foaming And Sensitizing Of Water-Bearing Explosives (IRFNA), hydrogen peroxide (H2O), aqueous hydroxylam With Hydrogen Peroxide, describes addition of hydrogen monium perchlorate (HAP) and nitrogen tetroxide (NTO). 25 peroxide as a foaming agent/Sensitizer to water-bearing Each of these liquid oxidizers has problems associated with explosives having and fuel. Here, the use. For example, LOX requires cryogenic Storage and is hydrogen peroxide is added to the thickened or emulsified dangerous when spilled. IRFNA, NTO and HO also have explosive mixture, and decomposes in the formulation to handling and toxicity problems. HAP offers some provide oxygen bubbles for foaming before the mixture is advantages, but Suffers from the presence of hydrochloric detonated. acid in the generated gas. Most of the liquid oxidizers in U.S. Pat. No. 4,047,988, to Weill et al., entitled Liquid current use present a vapor toxicity or contact hazard, and Monopropellant Compositions, describes a monopropellant are hypergolic, that is, spontaneously combusting, in the which is an aqueous Solution of a secondary or tertiary presence of fuels. amine, and an oxidizer Such as perchloric or nitric acid. Thus, there are in fact a limited number of available 35 Hydrogen peroxide is also mentioned as a possible oxidizer. choices of liquid oxidizers. That there is a need to fill the Here, the amine apparently Serves as the fuel in the mono technology "gap' in liquid oxidizers of the contemporary art propellant. Properties of the compositions including low is Seen, for example, in the following articles. In Mul, et al., freezing temperature, and use as a torpedo propellant, are described. Search For New Storable High Performance Propellants, 40 (AIAA-88-3354, AIAA/ASME/SAE/ASEE 24 Joint Pro U.S. Pat. No. 5,607,181, to Richardson et al., entitled pulsion Conference, Boston, July 1988), the authors discuss Liquid-Fueled Inflator With A Porous Containment Device, the need for Storable, non-cryogenic propellants with better describes an automotive airbag inflator using a liquid mono performance properties. They discuss nitric acid, NTO and propellant composed of a nitrate (HAN)/ hydrazinium perchlorate as Storable oxidizers. 45 triethanolamine nitrate (TEAN)/water system. A system Another problem with the available liquid oxidizers is that with and hydrogen peroxide as liquid fuel com they are mostly limited to a single composition, and thus a ponents is also mentioned. HAN is a relatively expensive Single Set of performance and physical properties. That is, component, however. Moreover, TEAN serves as a fuel in they are not formulated to achieve different values of per this mixture, So the mixture probably cannot Serve as a formance and physical parameters. Thus, variation of per 50 general oxidant for other fuels. formance properties of propellant Systems using these oxi In addition to the above patents, U.S. Statutory Invention dizers can only be achieved by varying the composition of Registration No. H1,768, to the fuel, thus limiting design options. Mueller et al., entitled Oxidizing Agent, describes liquid Anderson, W., et al., Low Cost Propulsion Using A oxidizers comprising water, hydroxylammonium nitrate, High-Density, Storable, and Clean Propellant Combination, 55 and ammonium nitrate or hydrazine mononitrate. Two oxi discuss the need for nontoxic, Storable, restartable, throttle dizing agents designated OXSOL 1 and OXSOL 2 are able and high density impluse Systems for rocket motorS. described. Discussed applications include use in gas gen They Suggest the use of high concentration hydrogen per erators for air bags, rocket propellants and torpedo propel oxide as a propellant. Although the authors describe hydro lants. gen peroxide as nontoxic, direct human contact with hydro 60 A document entitled Advanced Chemical Propulsion Sys gen peroxide is extremely dangerous. tems discusses the need to replace hydrazine as a fuel, and Rusek, J., New Decomposition Catalysts And Character suggests use of HAN/TEAN in a catalytic thruster. As noted ization Techniques For Rocket-Grade Hydrogen Peroxide, J. above, HAN is relatively expensive, and HAN/TEAN sys of Propulsion and Power, 1996, 12, 574-579, discusses the tem probably cannot be used as a general oxidant with other use of hydrogen peroxide as a , both as a 65 fuels. monopropellant and as an oxidizer with hydrazine hydrate/ An additional examples of a possible utility of a gas methyl alcohol fuel. generating System is seen in Berezovsky, Pyrogen Fire US 6,328,831 B1 3 4 Suppression System-Marine & Vehicle Applications, dated components, Such as a colorant, an odorant, a gelant, a August 1997, which describes a fire extinguishing System thixotropic agent, a Surfactant, or a burning rate modifier. (PyroGen) which is pyrotechnic-driven. The system pro In one embodiment, the gas-generating liquid composi duces an aeroSol, and the composition of the System is not tions of the present invention may be added to a fuel to form disclosed. a monopropellant. In another embodiment of the present Based on my reading of the contemporary art, I have invention, the gas-generating liquid composition may con decided that what is needed is a gas-generating liquid sist essentially of hydrogen peroxide, hydroxylammonium composition which can be used as an oxidizer, and which nitrate and water. Here, “consists essentially of means that has low cost, low toxicity and excellent handling properties. this composition has no added fuel, nor other component Substantially affecting the energy content, freezing point, or SUMMARY OF THE INVENTION density of the composition. Such a composition may have It is therefore an object of the present invention to provide minor additional components, Such as a colorant, an odorant, improved gas-generating liquid compositions. a gelant, a thixotropic agent, a Surfactant, or a burning rate It is also an object of the invention to provide improved modifier, which do not Substantially affect these parameters. liquid oxidizers for use in monopropellant and bipropellant 15 In addition to the compositions of the present invention, Systems. the invention also includes methods of use of the composi tions. Specifically, the compositions of the present invention It is another object of the invention to provide improved can be used for generating gas by passing the compositions liquid compositions for generation of breathable air. through a Solid catalyst bed, heating the compositions, or It is yet another object of the invention to provide gas adding catalyst to the compositions. The compositions can generating liquid compositions which have low cost. also be mixed with a fuel to form monopropellants or can be It is still another object to provide gas-generating liquid used in bipropellant and hybrid rocket Systems. compositions from readily available components. BRIEF DESCRIPTION OF THE DRAWINGS It is a further object to provide gas-generating liquid 25 compositions which have low vapor and skin toxicity. A more complete appreciation of the invention, and many It is a yet further object to provide gas-generating liquid of the attendant advantages, thereof, will be readily apparent compositions which have a low explosion hazard. as the same becomes better understood by reference to the It is a yet still further object to provide compositions following detailed description when considered in conjunc having excellent handling and Storage characteristics, Such tion with the accompanying drawings in which like refer as low corrosivity. ence Symbols indicate the same or Similar components, It is an additional object to provide gas-generating liquid wherein: compositions which are easy to prepare. FIG. 1 is a response Surface diagram illustrating freezing It is a yet additional object to provide gas-generating points of compositions of the present invention; and liquid compositions allowing ready production of custom 35 FIG. 2 is a response Surface diagram illustrating densities ized formulations. of compositions of the present invention. It is a still additional object of the invention to provide a gas-generating liquid having a low freezing point. DETAILED DESCRIPTION OF THE It is yet another object of the present invention to provide INVENTION a gas-generating liquid which has high density and high 40 The gas-generating liquid compositions of the present energy density. invention are a family of compositions which the inventor It is yet another object of the invention to provide a refers to as PERHAN. The general composition of the gas-generating liquid which is “green', that is, disposable water-based gas-generating liquid of the present invention without damage to the environment. 45 includes: hydrogen peroxide, hydroxylammonium nitrate It is still another object of the invention to provide a and water. The invention may also comprise any of a number gas-generating liquid which allows water-based cleanup of of additives, and may comprise a fuel. Spills. The present invention includes a family of compositions These objects are achieved in the present invention which with varying amounts of hydrogen peroxide, hydroxylam provides a family of water-based gas-generating liquid com 50 monium nitrate and water. Preparation of the compositions positions which may be used in rocket propulsion, torpedo of the present invention can generally be achieved Simply by propellants, air bags, and other applications. Applications the mixing the ingredients of the invention. Generally, the also include use in oxygen generators and in fuel cells. water concentration (that is, content) in the gas-generating The general composition of the water-based gas liquid will be in the range of approximately 10 to 50 percent generating liquid of the present invention includes: hydro 55 by weight (w/w-%), and the water concentration may be in gen peroxide, hydroxylammonium nitrate (HAN) and water. the range of 15 to 30 w/w-%. Generally, the hydroxylam Generally, the water concentration (that is, content) in the monium nitrate concentration will be in the range of gas-generating liquid will be in the range of approximately approximately 25 to 70 w/w-%, and may be in the range of 10 to 50 percent by weight (w/w-%), and the water concen approximately 30 to 60 w/w-%. The hydrogen peroxide will tration may be in the range of 15 to 30 w/w-%. Generally, 60 generally be in the range of approximately 15 to 50 W/w-% the hydroxylammonium nitrate concentration will be in the and may be in the range of approximately 25 to 40 w/w-%. range of approximately 20 to 70 w/w-%, and may be in the Different compositions will have different values of param range of approximately 30 to 60 w/w-%. The concentration eters relevant to the use of the invention, and thus custom of hydrogen peroxide will generally be in the range of ized compositions of the present invention may be prepared. approximately 15 to 50 W/w-% and may be in the range of 65 Among the advantages of the present invention are the approximately 25 to 40 W/w-%. The gas-generating liquid low freezing point achievable in Some compositions. An composition of the present invention may have additional important parameter of liquid gas-generating compositions US 6,328,831 B1 S 6 is the freezing point. At temperatures below the freezing point, Solids appear in the liquid, affecting many aspects of TABLE I-continued handling the liquid, for example, the ability to pump the liquid. In the present patent application, the term “freezing Observed Freezing Point ( C.) and Density (g/cc) point” is taken to be the temperature below which any for Various Compositions of Hydrogen Peroxide, precipitation occurs in a gas-generating liquid composition. Hydroxylammonium Nitrate and Water If, repeatedly, cooling the liquid below the freezing point Hydroxyl leads to precipitation and heating to a temperature above the ammonium Hydrogen Freezing freezing point allows redissolution, then the freezing point Nitrate Peroxide Water Point Density can be considered to be reasonably well defined. Generally, O.743 O.O56 O.2O1 -28 507 it is desirable that a gas-generating liquid composition be O.669 O.1 O.231 -37 472 0.827 O O.173 -8 545 Selected to have a freezing point below the ambient tem O.819 O O.181 -10 53 perature at which the composition will be used and Stored. O.803 O 0.197 -16 513 In order to determine the freezing point of a composition O.788 O O.212 -21 497 15 0.752 O O.248 -30 .462 of the present invention, the following method is used. This O.689 O O.311 -46 .4 method may be easily performed by one skilled in the art. A O.636 O O.364 -38 345 Sample of the liquid composition of interest is placed in a O.591 O O.409 -32 3O2 O.88 O O.12 3 599 16-mm test tube along with the bulb of a glass thermometer O.85 O O.15 4 574 of appropriate temperature range. Generally, enough liquid O.825 O 0.175 -5 549 to give a height of %" is used. The bottom portion of the test O.8 O O.2 -13 527 tube is then placed in a dry ice-ethanol bath in a Dewar flask. O O.35 O.65 -35 133 The Sample is cooled until crystals appear Visually in the O 0.5 0.5 -48 .192 O O.7 O.3 -40 284 liquid sample. The test tube is then removed from the bath 763 O27 210 -26 SO3 and is warmed as necessary with Stirring by the -709 OSO .241 -32 468 thermometer, until the crystals redissolve, noting the tem 25 .662 O70 268 -38 .443 62O O88 292 -42 .422 perature at which redissolution occurs. The test tube is then 763 O38 198 -22 SO6 cooled again in the bath to the noted temperature. While 709 O71 22O -33 481 Stirring, the test tube is cooled until crystals appear, and then .662 1O .238 -38 .456 removed to allow warming and dissolution. This is per 62O 125 255 -40 439 584 147 269 -43 .421 formed repeatedly until the temperature where a slight .544 171 .285 -46 .404 cooling causes crystal formation and slight warming allows 522 184 .293 -50 394 dissolution is found, and this temperature is recorded as the freezing point. Another advantage of the present invention is the high The freezing point data of Table I were statistically 35 analyzed and fitted to a cubic model, using the commercially density achievable in Some of the inventive compositions. available computer program STATGRAPHICS. Statistical Density is an important contribution to the energy content of analysis and response Surface modeling of this Sort is well a given composition, as more mass per unit Volume allows known in the art. A ternary composition response Surface more chemical energy per unit Volume. Likewise, greater diagram of freezing points for those compositions of the density also allows greater amount of gas generated per unit 40 present invention having only the three ingredients is pre Volume of liquid. In the present invention, density is pre sented as FIG. 1. It is evident from the data presented that Sented as Specific gravity, that is, a unitleSS value relative to the freezing points of compositions of the present invention the density of water at 4 C. Here, densities of the liquid are not readily predictable from only a few data of widely compositions are measured at room temperature, about 20 Spaced points on the ternary response diagram. The freezing C., using a commercial hydrometer, by method well known 45 point properties of these compositions could not have been in the art. predicted using current methods of the art without experi In Table I, freezing-point data and density data for mentation. However, by obtaining Sufficient data on a vari Selected compositions of hydrogen peroxide, hydroxylam ety of compositions, one skilled in the art should be able to monium nitrate and water. The table includes Some data for identify compositions of the present invention having freez compositions with no hydrogen peroxide or hydroxylam 50 ing points below -5° C. or alternatively below -40° C., as monium nitrate for comparison to compositions of the desired. For example, a freezing point of -5° C. might be present invention and for better understanding of the prop Suitable for Space flight applications, but a freezing point of erties of the present invention. -40 C. might be desirable for military applications in harsh environments. TABLE I 55 The density data of Table I were likewise analyzed and fitted to a quadratic model. A ternary composition response Observed Freezing Point ( C.) and Density (g/cc) for Various Compositions of Hydrogen Peroxide, Surface diagram of densities of compositions of the present Hydroxylammonium Nitrate and Water invention is presented as FIG. 2. By suitable experimentation, one skilled in the art should be able to Hydroxyl 60 identify compositions of the present invention with densities ammonium Hydrogen Freezing above 1.3, or alternatively above 1.4. The density of an Nitrate Peroxide Water Point Density energetic composition is an important parameter in the O.742 O.04 O.218 -15 1.504 performance of the composition in propellants, with greater O669 O.O7 O.261 -29 1.457 O608 O.095 0.297 -38 1.424 density generally allowing greater energy content per unit O.514 O.135 O.351 -53 1.375 65 Volume. 0.445 O.163 O.391 -52 1341 Another advantage of the present invention is the cus tomizability of the formulation. In particular, by adjusting US 6,328,831 B1 7 8 the water content of the final formulation, the combustion with the invention are alkylammonium and alkano temperature can be adjusted to give a desired flame tem lammonium nitrates having one, two or three carbon atoms. perature or to achieve Specific physical/chemical/Safety Monopropellants made using the liquid oxidizer of the properties. For example, this can reduce the Vulnerability present invention may be used for other purposes. If the characteristics and the corrosivity/erosion problems associ oxidizer containing hydrogen peroxide, ammonium nitrate ated with the exhaust gases. and water is mixed in appropriate ratio with a fuel, for Another advantage of the present invention is cost. example urea, an alkylammonium nitrate or hydrocarbon, Hydrogen peroxide, in particular, is relatively inexpensive. the decomposition reaction can in theory yield nitrogen, In addition to the hydrogen peroxide, hydroxylammonium carbon dioxide, carbon monoxide and water. Such a decom nitrate and water, compositions of the present invention may position mixture would not Support combustion, and might also contain additives to modify other properties of the be usable in air-bag inflation, fire Suppressant or related uses. gas-generating liquids. These additives usually total leSS In practice, most liquid propellant Systems use bipropel than 1 percent by weight of the composition. For example, lants. One problem with Some liquid monopropellants is the the composition may contain a colorant. This is a dye which low energy content of the monopropellant, in order to meet allows the gas-generating liquid to be more easily Seen. This 15 physical, chemical and Safety requirements. If the oxidizer is particularly useful, for example, in locating Spills. and fuel are separated, the Sensitivity to Shock, friction and Another additive which may be used is an odorant. This Static discharge are reduced. The homogeneous mixture of is a compound with an odor readily detected by the human the two components of a liquid propellant has a Sensitivity nose, and is generally used for detecting and locating Spills. which is greater than that of either component. Another additive which may be used is a stabilizer. This Bipropellant Systems are commonly used in rocket will usually be an oxygen Scavenger, Such as ammonium motors. In a bipropellant System, the liquid oxidizer contacts thiosulfate, which Serves to Slow chemical degradation of the fuel at the time of combustion. Rocket motorS may use the gas-generating liquid. liquid fuel, or in the case of hybrid rocket motors, the fuel may be Solid. The compositions of the present invention may Another additive which may be used is a chelating agent, 25 Such as ethylenediamine tetraacetic acid (EDTA) or cyclo be usable as liquid oxidizers for both kinds of rocket motors. hexanediaminetetraacetic acid (CDTA) or Sodium salts of Metallic additives may be added to these fuels to improve these compounds. Chelating agents Serve to bind impurity the propellants energy outputs. metal ions in the liquid, and can Serve to slow degradation In Table II, below, are tabulated theoretical performance of the gas-generating liquid. data for a bipropellant systems with a PERHAN oxidizer composition of the present invention, mixed with JP-10 fuel Another additive which may be used is a gelant, or gelling in the indicated oxidizer-to-fuel ratio. For comparison, a agent. Having the gas-generating liquid in gel form may be bipropellant using a mixture of HAN/water having the same useful in certain applications. water content as the composition of the present invention is Another additive which may be used is a thixotropic also tabulated. The bipropellant based on the PERHAN agent. Such an agent can improve the general handling 35 composition of the present invention is calculated to have a properties of the liquid, Such as pumping or pouring. greater than 15% increase in energy over the HAN/water Another additive which may be used is a burning rate composition, based on C* values. modifier. Such an additive affects the kinetics, or rate of burn Although the oxidizer composition of the present inven of compositions. tion is more energetic, this composition has a lower freezing Another additive which may be used is a Surfactant. 40 point and is expected to be less expensive than the HAN/ Surfactants can Serve to allow miscibility of the gas water composition. generating liquid with certain fuels. Also, a Surfactant can Serve to modify the droplet Size of the gas-generating liquid TABLE II when it is sprayed, for example into a rocket combustion 45 chamber. Theoretical Performance Data for a Selected Bi-Propellant The compositions of the present invention may be used as HO-Hydroxylammonium nitrate-Water ("PERHAN), JP-10 System liquid oxidizers for a variety of propellant Systems. In Oxidizer Chamber Im general, propellant Systems are monopropellant or bipropel Oxidizer Formulation To Fuel Temp. pulse Rho lant Systems. 50 In theory, a liquid monopropellant is the ideal energy % HAN 7% HO % HO Ratio Tc, F Isp Isp C: Source for various liquid gas generator applications Such as 62.O 12.5 25.5 12.2 3437 247 341. 4554 gun propellants, air bag inflators, torpedo propulsion and 75.2 O 24.8 13.1 3373 243 346 4486 rocket motors. The monopropellant's main advantage is Simplicity when compared to liquid bipropellant Systems: a 55 In general, catalytic or thermal combustion of an oxidizer monopropellant requires only half the number of pumps, composition of the present invention with low-carbon con Valves, Storage tanks and pipes. An example of a monopro tent fuel should generate an exhaust gas containing N2, pellant is the nitrate ester-based Otto fuel used in torpedoes. HO, and some CO. Catalytic or thermal combustion of an When used as a monopropellant, a composition of the oxidizer composition of the present invention should gen present invention would generally be preblended with a fuel. 60 erate an exhaust gas containing N2, H2O, CO, CO, CH and Such a fuel could be a water-soluble fuel, in which case the other gases. However, no HCN is expected in the exhaust fuel would generally dissolve in the liquid oxidizer. Non gas, unlike exhaust gases resulting from nitrate ester fuels. water Soluble fuels, Such as hydrocarbons, may also be used. The compositions of the present invention may also be Monopropellants using hydrocarbons and the liquid oxidiz decomposed to yield gases and energy. This decomposition ers of the present invention would generally be emulsified 65 may be achieved by catalysis. For example, placing the mixtures. In Some cases, Surfactants may be added to allow composition of the present invention in contact with a fixed for better emulsification. Among the fuels that may be used bed catalyst, such as Pt, Pd, or MnO, may yield decompo US 6,328,831 B1 10 sition. Such a reaction is well known in the art for other chemicals is extremely low in the compositions, and skin liquids, for example, hydrogen peroxide decomposing to toxicity is also expected to be relatively low. water and oxygen. Alternatively, the composition of the The preparation of the compositions from the constituent present invention might by decomposed by adding a catalyst ingredients is relatively simple and Safe, as the dissolution of the ingredients is generally an endothermic process. And, to the composition to dissolve or Suspend the catalyst. This due to the water Solubility of the components, water can be may be done in a catalyst Stream flow process. For example, used in the cleanup of Spills. The compositions of the the composition of the present invention and a catalyst could invention should be readily chemically degradable or be delivered from a bladder and mixed upon delivery, by biodegradable, simplifying disposal of the compositions. methods known in the art. The compositions of the present invention may be consid Alternatively, decomposition of a composition of the ered to be "green,” that is, not a hazard to the environment. present invention may be achievable by heating the com Thus, the compositions of the present invention have a position. If, for example, the composition is injected into a number of Significant advantages over liquid oxidizers and hot reaction chamber, the heat of decomposition may be other gas-generating compositions in present use. Sufficient to Self-Sustain the decomposition reaction, and a AS will be evident to those skilled in the art, various continuous decomposition of a Stream of the composition 15 combinations and modifications can be made in light of the may be possible. foregoing disclosures without departing from the Spirit or Scope of the disclosure. It is, therefore, to be understood that One possible application of decomposition of composi within the Scope of the appended claims the invention may tions of the present invention is in breathable air generators. be practiced otherwise than as Specifically described. Hydroxylammonium nitrate and hydrogen peroxide may be What is claimed is: theoretically decomposed to oxygen, nitrogen and water 1. A water-based, gas-generating liquid, comprising: according to the following Stoichiometries: hydrogen peroxide; hydroxylammonium nitrate; and Water. 25 2. The gas-generating liquid of claim 1, Said water being at a concentration in the range of approximately 10 to 50 Therefore, compositions of the present invention containing w/w-%. hydrogen peroxide, hydroxylammonium nitrate, and water 3. The gas-generating liquid of claim 2, Said water being can theoretically be decomposed into oxygen, nitrogen and at a concentration in the range of approximately 15 to 30 water. Such a decomposition could be used to create a gas w/w-%. mixture which could be used for breathable air. Unlike 4. The gas-generating liquid of claim 1, Said hydroxy chlorate-based Systems, the present invention would provide lammonium nitrate being at a concentration in the range of a mixture of oxygen and nitrogen, which may be better for approximately 20 to 70 w/w-%. use as breathable air at atmospheric pressure than pure 5. The gas-generating liquid of claim 4, said hydrogen peroxide being at a concentration in the range of approxi oxygen. Moreover, the present invention would yield no 35 mately 15 to 50 w/w-%. chlorine, which is a byproduct of chlorate candle Systems. 6. The gas-generating liquid of claim 4, Said hydroxy In Table III, below, are tabulated the theoretical perfor lammonium nitrate being at a concentration in the range of mance data as an oxygen generator for the composition of approximately 30 to 60 w/w-%. the present invention from Table II, and for a HAN/water 7. The gas-generating liquid of claim 1, Said hydrogen composition for comparison. The composition of the present 40 peroxide being at a concentration in the range of approxi invention has approximately 9.4% more available oxygen mately 15 to 50 w/w-%. than the HAN/water composition of the same water content, 8. The gas-generating liquid of claim 7, Said hydrogen and the two compositions can be seen to have Similar energy peroxide being at a concentration in the range of approxi outputs. The composition of the present invention has a 10 mately 25 to 40 w/w-%. C. lower freezing point than the comparable HAN/water 45 9. The gas-generating liquid of claim 1, Said gas composition, which may allow the present invention to be generating liquid being characterized by having a freezing uSable under extreme weather conditions. point below -5° C.

TABLE III Oxygen Gas Generator Theoretical Performance Data for a Selected HO Hwdroxylammonium nitrate-Water (“PERHAN Composition Chamber Exhaust Gas Composition, Oxidizer Formulation Temp. Impulse Rho moles/100 g Freezing Density % HAN 7% HO % HO Tc, F. Isp Isp C* HO N, O NO Point, C. g/cc 62.O 12.5 25.5 682 137 197 2396 3.07 O.65 0.83 O -40 1439 75.2 O 24.8 710 137 2OO 2414 2.94 O.78 O.78 O -30 1462

60 In addition to the described functional properties, the 10. The gas-generating liquid of claim 9, Said gas compositions of the present invention also have excellent generating liquid being characterized by having a freezing handling and Safety characteristics. Because they are non cryogenic, the problems associated with cryogenic materials point below -40 C. are avoided. Corrosivity is also expected to be relatively low, 11. The gas-generating liquid of claim 1, Said gas Simplifying Storage and handling. Due to the water content generating liquid being characterized by having a density and the use of protonated Salts, the vapor pressure of toxic above about 1.3. US 6,328,831 B1 11 12 12. The gas-generating liquid of claim 11, Said gas 19. A water-based, gas-generating liquid, consisting generating liquid being characterized by having a density essentially of: above about 1.4. hydrogen peroxide; 13. The gas-generating liquid of claim 1, further com prising a Stabilizer. hydroxylammonium nitrate; and 14. The gas-generating liquid of claim 1, further com Water. prising a chelating agent. 20. The gas-generating liquid of claim 19, Said water 15. The gas-generating liquid of claim 1, further com being at a concentration in the range of approximately 10 to prising a fuel. 50 W/w-%. 16. The gas-generating liquid of claim 15, Said fuel being 21. The gas-generating liquid of claim 19, Said hydroxy a hydrocarbon fuel. lammonium nitrate being at a concentration in the range of 17. The gas-generating liquid of claim 16, further com approximately 20 to 70 w/w-%. prising a Surfactant for Solubilizing the hydrocarbon fuel or 22. The gas-generating liquid of claim 19, Said hydrogen for adjusting the droplet size of the liquid. peroxide being at a concentration in the range of approxi 18. The gas-generating liquid of claim 15, Said fuel being 15 mately 15 to 50 w/w-%. an alkylammonium nitrate or alkanolammonium nitrate hav ing one, two or three carbon atoms. k k k k k