Sciencemadness Discussion Board

Highest Oxygen By Weight Compound?

MineMan - 30-10-2021 at 13:00

Hi All!

I came across a paper a few years ago that I cannot find now. It was a thermite mixture of 70 percent aluminum. I think it used a dense metal oxide or carbonate. Does anyone know the highest density oxidizer (most oxygen per unit volume)?

So far the best I have found is MoO3, but that isn’t much better than standard less exotic options.

DraconicAcid - 30-10-2021 at 14:51

Potassium ozonide can be made, and that's KO3.

Vomaturge - 30-10-2021 at 21:52

If it could form in a pure anhydrous state Be(ClO4)2 would be up there, but it's toxic, exotic, and costly enough that it probably doesn't have a clear advantage over nuclear. I mean, it's easier to scale down, but still impractical in so many ways.

H2O2 has a high mass fraction but the actual energy release will be lower because you're either reducing hydrogen (in the case of a powerful fuel like Al) or else only using half the oxygen and being left with a bunch of extra water or steam.

Even a stoichiometric mix of straight O2 or O3 and Al is only like 53% aluminum so this 70% mix will be fuel rich no matter what. Also if its a patent they often cover a wide range of embodiments, only some of which are actually useful.

Edit: I was thinking mass fraction of Oxygen, not density of oxygen per unit volume. My bad. The part about aluminum stoichiometry is still valid though.

[Edited on 31-10-2021 by Vomaturge]

BromicAcid - 31-10-2021 at 05:58

Nitronium perchlorate has to be pretty up there even with the chloro:

2.2 g/mL
145.5 g/mol =>65.97% Oxygen
1.45 g/mL Oxygen

Liquid oxygen is only 1.14 g/mL at its BP so oxygen density is greater than liquid oxygen.

Then again, lithium perchlorate would give about the same oxygen density without the corrosivity issues.

[Edited on 10/31/2021 by BromicAcid]

unionised - 31-10-2021 at 07:26

H2O3 will be hard to beat in terms of % oxygen by weight (about 96%).
https://en.wikipedia.org/wiki/Trioxidane

If you are looking for something to mix with a fuel, you can simply use oxygen (100%).
https://en.wikipedia.org/wiki/Oxyliquit

Tsjerk - 31-10-2021 at 08:43

Quote: Originally posted by BromicAcid  
Nitronium perchlorate has to be pretty up there even with the chloro:

2.2 g/mL
145.5 g/mol =>65.97% Oxygen
1.45 g/mL Oxygen

Liquid oxygen is only 1.14 g/mL at its BP so oxygen density is greater than liquid oxygen.

Then again, lithium perchlorate would give about the same oxygen density without the corrosivity issues.

[Edited on 10/31/2021 by BromicAcid]


Liquid ozone comes pretty close with 1.35!

https://aip.scitation.org/doi/10.1063/1.1743870

unionised - 31-10-2021 at 10:09

Alumina has a density of 3.987 g/ml and a molecular mass of 101.96
So each gram contains about 48/102 g of oxygen.
About 0.47 grams of oxygen in 1/3.987 ml of alumina.

So it contains about 1.87 grams of oxygen per gram.

On a mass of oxygen per unit volume basis, it is an excellent oxidising agent.
But not on any other basis.


Tsjerk - 31-10-2021 at 11:28

Quote: Originally posted by unionised  

So it contains about 1.87 grams of oxygen per gram.


Per cubic centimeter, but of course the question didn't make sense to start with.

clearly_not_atara - 31-10-2021 at 11:53

If you want a thermite mixture, I doubt something as unstable as trioxidane or ozone would qualify. Nitronium perchlorate is hypergolic with most fuels.

It's hard to beat KNO3. The Na/Li equivalents are deliquescent. Transition metal compounds like KMnO4 and K3CrO8 are well behind in electrons accepted per gram or cc.

EDIT: If MgFeO4 is stable it might win the non-nitrate contest.

[Edited on 31-10-2021 by clearly_not_atara]

Vomaturge - 31-10-2021 at 14:12

Was this the paper you were looking for? I found it by googling 70% aluminum thermite.

On a distantly related note, there is apparently a narrow temperature window where O2, and CH4 can coexist as miscible liquids. The 4:1 solution has a lower heating value of about 10kj/gm, is capable of 5+km/sec VOD, and has one of the hottest reaction temperatures of any organic based EM at about 5500C.

[Edited on 31-10-2021 by Vomaturge]

MineMan - 31-10-2021 at 20:08

Hey all! Thank you for your input!

To clarify. If my memory serves me correct the thermite had an energy of 50kj/cc without the use of air. The highest I can find is MoO3 with Al which is about 25kj/cc. I am not seeing how this is possible? Does anyone know the highest energy per CC stable oxidizer and fuel mix? I was thinking maybe it would be lanthanides oxides and rare earth fuels? Certainly a computer program could spit this out. The best I have come up with so far is PTFE plus Li or B.

Vomaturge - 1-11-2021 at 11:01

If my math is right, with the heat of formation of Al2O3 (1675kj for 54 gm of Al and 48 of O)and density of Al (about 2.7kg/l) aluminum will be about 60% of that composition by volume. The oxide would need at least 3.55 g/cc of elemental oxygen content. Once you consider the energy to break up the oxide, you probably need way more than 60% aluminum by volume, and a much denser oxygen source to get 50kj/cc

[Edited on 2-11-2021 by Vomaturge]

MineMan - 4-11-2021 at 17:44

It looks like I2O5 is probably the best :)

unionised - 5-11-2021 at 03:13

Quote: Originally posted by MineMan  
It looks like I2O5 is probably the best :)

In what way?