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Topic: Produce a low-freezing rocket fuel  (Read 43729 times)

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Offline rolnor

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Re: Produce a low-freezing rocket fuel
« Reply #60 on: February 14, 2022, 01:07:40 AM »
OK. Yes, nitromethane has the same explosive force as TNT as I understand. I powered a moped with almost pure nitromethane, I got it from Nobel-industries where I worked in summertime in my teens. The engine sounded strange but it run OK. I think you need to adjust the ignition if you use nitro, it should have produced more power than it did.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #61 on: February 14, 2022, 09:16:23 AM »
Polyisoprene to branched alkanes, update without carboxylic acids, and possibly less wrong.
  • Ozonolysis, under conditions (RT?) that destroy the ozonides and produce aldehydes and ketones.
  • Hydrogenation of the double bonds, under conditions that keep the aldehydes and ketones.
  • Reduction of the aldehydes and ketones with zinc (Clemmensen or other, I don't know).
Variant:
  • Ozonolysis to aldehydes and ketones.
  • Hydrogenation of the double bonds, aldehydes and ketones.
  • Dehydration of the alcohols.
  • Hydrogenation of the new double bonds.
Better?

[...] I powered a moped with almost pure nitromethane [...]
;D

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #62 on: February 19, 2022, 05:04:32 PM »
[...] I powered a moped with almost pure nitromethane [...]

Was it for the moped show?

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #63 on: July 22, 2023, 09:53:20 AM »
Pmdeta melts at -52°C, lower would make a more runny fuel in Kiruna in Winter or help spend the night on the Moon or Mars. I suggest 3 possibilities:

Ethyls replace randomly some methyls. Still starting from cheap Deta. The mix of 9 products plus the stereoisomers shall freeze less easily.

Ethyls at the ends provide more stereoisomers. Ethylene oxide is to stop at the ethanolamine, the safer glycol costs only more separation and losses.

Ethyl at one end, mostly propyl at the other. The excess methylamine limits the ethyl at the second end, which hurts little and may build a eutectic.

The same can be done with propylamines. They tend to be more viscous than ethylamines.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #64 on: July 22, 2023, 10:34:25 AM »
The direct reaction between an amine and an alcohol uses Pd or Ir as a catalyst.
A more classical path, Eschweiler–Clarke, consumes formaldehyde and formic acid to methylate amines. I suppose ethanal  and formic acid ethylates them.

Offline wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #65 on: July 24, 2023, 10:02:13 PM »
Enthalpy, I'm about to blow your mind

https://chemdrawdirect.perkinelmer.cloud/js/sample/index.html

I can't handle your wacky amines and bond angles anymore.


Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #66 on: July 26, 2023, 08:29:56 AM »
 ;D But at least my colours are nice, I hope.

Offline marquis

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Re: Produce a low-freezing rocket fuel
« Reply #67 on: July 26, 2023, 08:26:18 PM »
If you want to get polyisoprene, especially vulcanized polyisoprene, down to its oligomers fast, the easy way to do it is pyrolysis. We'd do it for analysis of polyisoprene polymers by pyrolysis/ gc/ ms. As well as the normal pyrolysis FTIR. Yes, there will be energy input.  But that's the price you pay.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #68 on: July 27, 2023, 09:02:08 AM »
Hi Marquis and the others, thanks for the interest!

Energy input is no huge worry for rocket fuels, whose cost isn't as extremely constrained as boat or plane fuels. So yes, pyrolysis of recycled tyres is one very interesting option. More so because the cost of garbage tyres is zero and they can provide the energy and the later hydrogen too.

Though, pyrolysis produces many compounds like aromatics, unwanted in the fuel nor in the dump. Tuning the conditions improves that, catalysts maybe too. The other option I considered here is ozonolysis, which targets specifically the double bonds and produces much more selectively the desired oligomers.

This depends on implementation at the right scale and at acceptable cost, nothing granted.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #69 on: August 09, 2023, 07:38:32 AM »
A rocket company doesn't even have to permethylate ethylene or propylene amines. At least Huntsman and Koei sell them, ready to torch (they imagine other uses).
They call the permethylated diethylene triamine Pmdeta and the dipropylene C3060 3503 (Koei) or ZR-40 (Huntsman).
Huntsman's secondary amine Z-130 has a good liquid range too and could be ethylated. Then, 2-4 compounds could make eutectics. Favour the more energetic ethylene amines.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #70 on: September 28, 2023, 07:38:49 PM »
Teta (triethylene tetramine) improves the flash point and the odour over Deta (diethylene triamine) while keeping mp=-35°C against -39°C. Viscosity worsens, but peralkylation would remedy it and improve the mp. Peralkylated branched triethylene tetramine is especially easy to produce and can mix many (near-) isomers for better mp and η. It should be more runny than the linear version, but I lack data. Some optional propylene diamine would exacerbate the colligative effects.

Starting from ethanolamine, ethanol, methanol, ammonia is possible too.

Marc Schaefer, aka Enthalpy

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