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Topic: Produce a low-freezing rocket fuel  (Read 19632 times)

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Online wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #30 on: July 17, 2017, 09:53:24 AM »
https://en.wikipedia.org/wiki/Polysilane#Properties

It appears they are sensitive to UV as a small caveat, and while the wikipedia article isnt explicit, they seem to be solids. Are you thinking more towards the small molecule angle for this? I'm a polymer chemist so my mind goes straight to polymers due to their processability and generally superior mechanical properties.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #31 on: July 17, 2017, 09:55:33 AM »
If the low melting point of siloxanes, tetramethylsilane and hopefully silicon-containing alkanes results from the ease of rotation at Si-O and Si-C bonds, making the deformed molecules hard to stack orderly, then much void must remain between the molecules and disappear at high pressure.

This would give silicon-containing alkanes a bulk modulus as low as, or maybe lower than, silicones - the reference materials for low bulk modulus (big volume compressibility).

A low bulk modulus would be a drawback as a (aeroplane) hydraulic fluid, but an advantage in volumic springs, where a piston compresses a liquid or solid which is often silicone oil up to now, or in windows and lenses for underwater acoustics which use polymethylpentene (PMP) presently.

A solid silicon-containing alkane could hopefully result from disubstituted silane and a diene.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #32 on: July 17, 2017, 10:53:02 AM »
https://en.wikipedia.org/wiki/Polysilane#Properties
It appears they are sensitive to UV as a small caveat, and while the wikipedia article isnt explicit, they seem to be solids. Are you thinking more towards the small molecule angle for this? I'm a polymer chemist so my mind goes straight to polymers due to their processability and generally superior mechanical properties.

I have obviously nothing against polymers nor polysilane. Wiki tells implicitly that the polymers are solids: crystalline to amorphous, and so on.

My initial thoughts were about a few silicon atoms where the alkane is branched, but if a polysilane has good properties, it's just fine. UV are present in some applications only.

Dimethyldichlorosilane is widely available as the precursor to polydimethylsiloxane but it said to cost a bit. Silane is hopefully cheaper. That said, some uses accept more expensive compounds: vacuum grease, computer coolant, underwater acoustics, volumic springs and others.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #33 on: May 16, 2018, 05:56:28 PM »
Easy precursors of farnesane make most of the oil of Ocotea caparrapi.

Citing Palomino et al
http://www.academia.edu/11238744/Caparratriene_an_Active_Sesquiterpene_Hydrocarbon_from_Ocotea_caparrapi
incisions in the large Colombian tree secrete oil comprising mostly nerolidol, together with caparrapi oxide, and the diol and triol analogues of nerolidol, plus a bit of caparratriene.

It is my hope that indistinct dehydration of the mixture provides hydrocarbons with the proper skeleton, whose hydrogenation gives mainly farnesane with a nice mix of stereoisomers - or hydrogenate first or in several steps. The intermediate alkene may also grow longer chains easily, preferred for flash point and lubrification. Beware caparratriene is a cell growth inhibitor.

Palomino et al got their >100g sample from the market in Caparrapi. Incisions in trees make latex for cheap, Ocotea caparrapi oil hopefully too. Competing against Kerosene and Diesel oil is presently uncertain, but hydraulic fluid, transformer oil, cooling oil seem easy markets, Mars and Moon landers obviously.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #34 on: May 17, 2018, 11:50:26 AM »
Trying to compare the production of Ocotea caparrapi oil with latex, without reliable sources...

The tree is banal in a part of Colombia. Producing its oil resembles more an individual and occasional activity exploiting isolated uncultivated trees.

One Ocotea caparrapi seems to produce as much per year as one hevea, need more area but far less work. Selection and optimization would improve the yield. Automation looks feasible.

Latex sells for 1.5usd/kg presently. Prior to heavy investments, farnesane a few times more expensive would not replace aeroplane and car fuels, but address easily all other markets.

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As an early alternative to start an activity, farnesol sells for some 30usd/kg on Alibaba. It's nearly nerolidol, with one double bond and the hydroxyl elsewhere. Cheap enough for Mars landers and others.

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Looks like Amyris, who initially wanted to fly aeroplanes with farnesane produced by bacteria, have good readings
https://www.energy.gov/sites/prod/files/2014/11/f19/x_velasco_biomass_2014.pdf
page 6: lubricants, transformer oil, hydraulic oil.

Together with partners, they flew airliners with farnesane, kudos. As a costly demonstration, but this is already admirable.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #35 on: March 21, 2019, 05:10:50 PM »
Since Juul has a nice application for low-freezing heavy alkanes
https://www.chemicalforums.com/index.php?topic=99108.0
maybe you chemists could give opinions, comments, remarks about farnesane obtained from caparrapi oil?

The tree, Ocotea caparrapi or Nates Dugand Lauraceae, is an endangered species. Apparently no restriction on its oil, or rather resin. I hope a commercial use of living trees would help the species rather than threaten it.

The resin comprises mainly nerolidol and caparrapi oxide, plus a bit of diol and triol whose loss wouldn't be bad, plus a zillion minor compounds, and traces of caparratriene that can be lost. Image appended.

Caparrapi oxide might allegedly result from the cyclisation of nerolidol. Unless someone sees how to de-cyclise it to the proper skeleton, I'd remove it by distillation at low pressure. It may serve as a hydrogen source or a perfume.

1atm boiling points estimated (!) by Mpbpvp:
+256°C Caparratriene
+256°C Caparrapi oxide
+292°C Nerolidol (measured +276°C)
+319°C Caparrapidiol
+344°C Caparrapitriol

I haven't seen how to remove the alcohols and saturate the double bonds at once. Two steps hence.

To remove the alcohols, I've found only dehydrations. They create a double bond whose random location is unimportant here. Tertiary alcohols are said not to make ethers. At least three usual ways:
  • Concentrated phosphoric acid. But it takes sulphuric acid to regenerate anyway.
  • Concentrated sulfuric acid. Regenerate by heat, is that correct?
  • Alumina, safest. At reduced pressure, the reactants can be gaseous if this helps. Regenerate by heat I believe.
Nerolidol, diol and triol would provide caparratriene and isomers with the same skeleton. I suppose they are too difficult to separate from caparrapi oxide, which is hence distilled away before. Though, if for instance polymerisation of the allenes is likely during the dehydration, maybe the hydrogenation can be done first, and Caparrapi oxide or its products removed by cold and filtration? Or should the dehydration proceed with added hydrogen?

Hydrogenation of all double bonds is usually made by H2 and Pd/C, unless someone knows a better way. The resulting broad mix of right-left isomers contributes to the low melting point.

Thank you!

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #36 on: March 27, 2019, 10:49:44 AM »
Will the diene polymerise spontaneously during the dehydration attempt?

Online wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #37 on: March 27, 2019, 11:20:27 AM »
Temperature dependant.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #38 on: March 28, 2019, 06:49:45 AM »
Ouch... With sulphuric acid, dehydration temperatures are like 140°C, and with alumina (which is a catalyst, not a water absorbing reactant as I had imagined) rather 300°C. But the pressure can be lowered, ah.

Sulphuric acid is a catalyst in alkylation reactions, and fine alumina powder catalyses many reactions.

Dehydration of nerolidol would create ramified dienes, probably conjugated.

Any chance that the dienes don't dimerize immediately?

Online wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #39 on: March 28, 2019, 09:33:07 AM »
The conjugated ones are the most worrisome. It's like butadiene to make rubber.

Let me look in on how butadiene polymerization is done to see if my hunch is right.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #40 on: March 29, 2019, 07:20:59 AM »
Ahum. Alkylation units operate at +16°C with alkenes, less prone to polymerization than conjugated dienes, using sulphuric acid as the only catalyst
http://www2.dupont.com/Clean_Technologies/en_US/assets/downloads/AlkyUnitDesign2001.pdf

Can I forget the sulphuric route?

On the other hand, the similar myrcene has a measured boiling point of +167°C
https://en.wikipedia.org/wiki/Myrcene
so it doesn't polymerize immediately at that temperature, and it's obtained by pyrolysis of β-pinene at +400°C, so at this temperature it has some stability. Alumina route then?

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #41 on: April 02, 2019, 07:23:22 AM »
Can a single step reduce the alcohols and the double bonds at once?

I have only found subtle reactions intending to preserve the functions of alkenes, enantiomers and so on, but what is needed here is a brutal reduction that keeps the C-C bonds, nothing more.

Heat and hydrogen must be available from the discarded caparrapi oxide.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #42 on: April 12, 2019, 07:06:09 PM »
From reading and partial understanding of reduction and hydrogenation reactions, comments welcome:
  • Usual reductions stop at alcohols.
  • Exotic ones achieve the alkane but need fancy reactants like silanes and may remove a carbon.
  • Hydrogenation is compatible with alcohols.
So, better one easy step more in the process than synthesizing a fancy reactant. Unless someone has a better idea, the process from caparrapi resin to farnesane would look like:
  • Distill the caparrapi oxide and caparratriene away. They will provide hydrogen and heat.
  • Saturate the double bonds with H2. The hydroxyls stay.
  • Dehydrate with sulphuric acid or over alumina, get double bonds.
    * Regenerate the acid by heat.
    * Or absorb the vapour downstream the alumina, and regenerate the dessicant.
  • Saturate the new double bonds with H2.
  • Purify.
Simply by partial oxidation of only the caparrapi oxide with air
C15H26O + 7×O2 :rarrow: 15×CO + 13×H2
while the conversion of nerolidol, diol, triol consumes 4×H2, so most resin compositions need no steam reforming and waste no alcohol.

CO burners heat the process. Heat exchangers can save caparrapi oxide if it has a market value (perfume).

The process seems to consume only caparrapi resin ("oil"), labour, air, fuel only at start, little electricity, no water. Waste are vapour and carbon dioxide, by-products are caparrapi oxide and little caparratriene, a cell growth inhibitor.

The plant can operate in the middle of an Ocotea caparrapi plantation if desired.

Marc Schaefer, aka Enthalpy

Online wildfyr

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Re: Produce a low-freezing rocket fuel
« Reply #43 on: April 12, 2019, 09:47:19 PM »
Let's find 50 million in start up funds and get cranking!

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #44 on: April 14, 2019, 07:30:08 PM »
 ;D and in a nice country. Choose the altitude for the temperature, it's constant all the year under the equator
https://es.wikipedia.org/wiki/Caparrap%C3%AD

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