O2 vs. O4

Oxygen is used in many areas of human activity. Every year, millions of tons of oxygen are extracted from the atmospheric air and stored in a compressed and liquid state. Oxygen, however, has a low critical temperature (-118.38°C) and a high critical pressure due to its low molecular mass, making its long-term storage quite challenging and expensive. 

Design and development of propulsion solutions which exploit high density, storable and rapidly loadable propellants are essential for the national defense and space exploration.

Our team has invented a method, designed and built a device for production of a new long-term storage-stable allotropic modification of oxygen, tetraoxygen O4, using a combination of known chemical reactions into one technological sequence, including chemical interaction of negative and positive oxidation state oxygen compounds.

The laboratory tetraoxygen synthesizing device was designed, built and successfully used by our team for production of tetraoxygen. 

Tetraoxygen O4 is non-toxic, stable in its liquid state up to around +109.4°F (+43°C) with twice the density that of liquid oxygen due to a double molecular weight. The temperature of thermal dissociation of its molecule into two molecules of oxygen O2 is about +392°F (+200°C). Liquid tetraoxygen has a light lilac color with a density of 2.15 g/cm3. Tetraoxygen is not soluble in water, and has a mobile-liquid viscosity.

The proposed tetraoxygen production method and the work plan have been analyzed by the NASA environmental office, and were determined to be environmentally safe. 

Oxygen is one of the main and the best rocket fuel oxidizers. Oxygen is one of the most widely used gases in many areas of human activity. Every year, millions of tons of oxygen are extracted from air and stored in a compressed gaseous or liquid state.

Tetraoxygen can be used directly instead of oxygen as rocket fuel oxidizer, in metallurgical, chemical and many other industries. As an oxidizing agent, tetraoxygen acts exactly as oxygen, forming exactly the same resultant compounds.

While considering the space exploration, oxidizer's storage temperature is extremely important. An oxidizer with a low storage temperature, i.e. cryogenic liquid oxygen, requires thermal insulation, special handling procedures, thus further increasing the mass of a rocket, complicating tasks and decreasing the safety at a launch site.

Liquid tetraoxygen eliminates the cryogenic storage and many of the safety issues attributed to liquid oxygen.

There is another important factor that must be also taken into consideration, the oxidizer's density. Using a high-density oxidizer means a rocket requires smaller storage tanks, thus decreasing the mass of a launch vehicle.

Tetraoxygen has double the density of oxygen.

This means the capacity of oxidizing agent tanks can be halved for the same oxidizing capacity. Therefore their mass can also be reduced. In addition, their mechanical stability increases due to decreased size. The tank's wall and longitudinal stiffeners become thinner and lighter. All of the above will significantly reduce the mass of rocket tanks, decrease oxidizer evaporation losses, eliminate complex and expensive cryogenic equipment and procedures, increase safety.

The toxicity of the propellant is likewise important. Safety hazards exist when handling, transporting, and storing highly toxic compounds.

Tetraoxygen is non-toxic.

Tetraoxygen is an ideal non-cryogenic rocket fuel oxidizer because it is not toxic, has low vapor pressure, high density in liquid state. When the fuel is oxidized, tetraoxygen forms the same substances as molecular oxygen. The stability of the tetraoxygen molecule is explained by the fact that all oxygen atoms in it are surrounded by octet of electrons, and each atom is associated with two neighboring atoms by common electron pairs of paired electrons. Moreover, all atoms in tetraoxygen are equivalent and closed in a ring.

The oxidizing ability of one molecule of tetraoxygen is the same as that of two molecules of triplet oxygen O2: two molecules (4 atoms) of oxygen O2 are able to pull away eight electrons from a reducing agent, one molecule (4 atoms) of tetraoxygen O4 also pulls away eight electrons from the same reducing agent. Accordingly, 1 g-mole (64 g) of tetraoxygen oxidizes eight fuel equivalents, and 2 g-mole (32 X 2 = 64 g) of oxygen also oxidize eight fuel equivalents. Therefore, when using tetraoxygen as an oxidizing agent for rocket fuel, it is necessary to take it by weight as much as liquid oxygen.

One of the distinctive features of tetraoxygen is its rather high energy of formation (Gibbs standard energy ΔH): 217 kJ/mole or 3,391 KJ/kg. This energy is “stored” in O4 molecules during their formation and is released at the moment of O4 molecule dissociation, i.e. at the time of rocket fuel burning. When kerosene is oxidized by liquid oxygen, it releases specific energy of 43 MJ/kg of kerosene or 9.58 MJ/kg of kerosene-oxygen mixture. Replacing O2 oxygen with O4 tetraoxygen will provide additional 2.63 MJ per 1 kg of kerosene-tetraoxygen propellant mixture. In addition, a surplus energy of 160 kJ per 0.778 kg O2, or 1 kg of kerosene-oxygen mixture, which is spent for liquid oxygen heating from -297.3°F (-183°C), is to be added to equation. As a result, the specific energy of kerosene-tetraoxygen mixture equals 12,368 MJ/kg. This is a 29.1% increase in comparison with liquid oxygen + kerosene propellant.

That is why the specific impulse of the kerosene-tetraoxygen pair turns out to be as high as 4250 m/s. This, in combination with stability, non-toxicity, rather high boiling point and density, make tetraoxygen a perfect rocket fuel oxidizer.

Tetraoxygen-based propellants provide the high thrust to weight and specific impulse needed to achieve high change in velocities (delta V), due to tetraoxygen’s high density, and are storable under normal temperature and rapidly loadable. Tetraoxygen can be stored inside the tanks of a launch vehicle for as long as it’s necessary without any need to offload it as any other cryogenic and/or toxic rocket fuel oxidizers.

The use of tetraoxygen O4 as a rocket fuel oxidizer allows to combine all of the advantages of traditional cryogenic fuel combinations within a non-cryogenic environment, as well as drastically increase the specific impulse, thrust, readiness-to-launch and safety of the personnel.

Tetraoxygen could replace oxygen in national defense applications while significantly increasing safety of military personnel by, for instance, eliminating a need in pressurized oxygen tanks that are a potential deadly hazard aboard of submarines or aircraft. 

The use of tetraoxygen for long-term compact storage of oxygen is possible due to its ability to decompose with formation of gaseous oxygen at the temperature of about +392°F (+200°C):

The decomposition of 1 liter (2.15 kg) of liquid tetraoxygen produces 1505 liters of pure oxygen gas. Thus, 5 L (10.75 kg) of liquid tetraoxygen would replace a 50 L cylinder with compressed oxygen under the pressure of 150 atm. Considering that a steel oxygen cylinder weighs about 100 kg (220 lb.), replacing oxygen with tetraoxygen on airplanes, submarines and spaceships could provide up to 90% of space and weight savings.

Our team intends to develop a safe, efficient and commercially viable tetraoxygen industrial production process, as well as design several end-user-oriented devices i.e. medical oxygen delivery systems, catalytic converters for tetraoxygen dissociation with formation of gaseous oxygen for applications in which tetraoxygen cannot be used directly e.g. healthcare facilities, aircraft, submarines, spacecraft and many others.