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Topic: Produce a low-freezing rocket fuel  (Read 44169 times)

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Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #45 on: April 15, 2019, 11:09:27 AM »
The usual process to separate H2 from CO, N2 and others after partial oxidation seems to be pressure swing adsorption (PSA). Looks simple and efficient. It can separate CO from N2 too, or maybe it's better to remove N2 from O2 prior to partial oxidation.

I've not found how quickly Ocotea caparrapi grows. Just "large tree (25m)" or "20m de altura". "Humid area surrounding the town of Caparrapi" suggests a fast growth under the equator.
https://es.wikipedia.org/wiki/Ocotea_caparrapi
https://www.academia.edu/15574491/Bandoni_LOS_RECURSOS_VEGETALES_AROM%C3%81TICOS_EN_LATINOAM%C3%89RICA_
https://pubs.acs.org/doi/pdf/10.1021/np960012r

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #46 on: May 30, 2019, 06:44:56 PM »
Turpentine and other paper by-products make decent fuels, possibly separated as beta-pinene, alpha-pinene, carene, optionally saturated. But their big ring brings no or little heat of formation, loses two hydrogen atoms, and makes a stiffer molecule more prone to freeze. Due to C10, the flash point could be higher.

Maybe metathesis affords better molecules. Ethylene would make a C12, uneasily flammable. The flexible, open and very unsymmetric backbone should be harder to freeze. As is, it might be a (component of) jet fuel, or a Diesel fuel since the C3 chain eases autoignition. After saturation with hydrogen, it could be a rocket fuel, not magic but easily produced.

Beta-pinene, which has other uses, wouldn't fit as its double bond isn't in the ring. Carene I suppose neither because its big ring is unstrained. But alpha-pinene, otherwise little useful, has a double bond in its strained ring, which should help the metathesis.

The product has one very accessible double bond and may readily dimerize. I hope the strain in alpha-pinene lets the useful reaction outpace the unwanted one.

Comments please?
Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #47 on: June 02, 2019, 06:30:39 PM »
It goes without saying, but maybe better if I say it: longer alkenes can react with alpha-pinene to produce bigger molecules.

Symmetric alkenes like 2-butene would remain identical if reacting among themselves, but I suppose the double bond of alpha-pinene is too crowded for them.

Longer straight 1-alkenes (cheap propene, butene...) would increase the boiling and flash points of the product and ease its autoignition, while branched ones make autoignition harder if any useful. In a jet engine, a broader spectrum of boiling points stabilizes the flame, while in a Diesel engine, more uniform properties reduce sooting. This holds for metathesis products alone (synthetic fuels are a known solution to Diesel sooting), which can already be a mix, and holds also for mixes with biofuels or fossil fuels.

The longer metathesis products, having no fully exposed double bond, should be less prone to further metathesis.

Saturating the double bonds would improve the energy per mass unit of a jet fuel. If the alkene is obtained from methane of from C3 and C4 fractions, hydrogen is available.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #48 on: January 22, 2020, 07:02:14 AM »
More about uses at wind music instruments.

Most woodwinds assemble several joints with corks for airtightness. The corks are greased to glide and be more airtight. Here in rich Europe, I got 15g of cork grease for 5€ at the store, and over the Web, shipping makes the same sum. That's 300€/kg at retail for a petrol derivate, wow. The grease isn't as refined as are some paraffins. It stinks, and the manufacturer adds a strong smell to conceal it. Yamaha produces already a synthetic grease that sells for twice as much. Room for profit!

Light oil lubricates the keyworks of woodwinds. It's standard mechanical oil from what I've seen, and it dries in months, while professionals let overhaul their instrument every second year, amateurs less often, and sometimes an instrument idles for decades but shouldn't corrode. Slower evaporation would bring much, as a corrosion protection and as a lubricant. But the temperature range is tiny, the contact pressure and the shear number too, so true lubricating oils are not needed. Many compounds could beat mechanical oils here, maybe squalane (used in cosmetics) or a longer version of farnesane.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #49 on: January 26, 2020, 05:51:05 PM »
No exotic synthetic molecules mandatory as grease and oil for wind instruments: triglycerides should suffice. They are cheap, and their bigger molecules evaporate slower than squalane.

Tallow served for centuries as an excellent cork grease, but its ill-defined animal origin has drawbacks for Jews, Hindus, Muslims, vegans and the many people who find it disgusting. It may also stink and deteriorate at air. Similar palm oil (a solid) improves much. As sold for cooking, it's already refined, bleached and deodorized
https://en.wikipedia.org/wiki/Palm_oil
Further treatment can stabilize its properties for a long time: hydrogenation, fractionation... It's done for industrial pastry. Heating once in a pan at the user's home, possibly under limited air,  would remove humidity and volatiles.

Palm kernel oil is generally liquid despite being strongly saturated, thanks to its shorter fatty acids
https://en.wikipedia.org/wiki/Palm_kernel_oil
and while other cooking oils serve as lubricants, at chainsaws for instance, palm kernel oil is reportedly stable over longer time. Here too, products reaching rich consumers are already well processed, but further simple treatments like hydrogenation and fractionation would make a long-lived keyworks lubricant. Removing free acids and C4 acids seems important.

Make simple treatments on palm oil, sell for 300€/kg, that sounds good.
Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #50 on: January 30, 2020, 06:42:46 PM »
I've bought for 1.5€ 1kg of allegedly edible palm oil, and as a lubricating grease it's fabulous for music instruments, extremely effective. Tallow must have been that good.

Zero odour, vegan, no known allergies, should fit many faiths. Share the 150 cents among 60 musicians if you wish. One year indicative shelf life is fine for cork grease that we replenish more often.

Any reason to improve the grease before repackaging it in 15g units and selling each for 5€? Time will tell if it smells unpleasantly after years. And while this palm+canola solid mix is easily rubbed on corks, musicians are used to softer pastes. So maybe palm oil and a lighter triglyceride like palm kernel oil could be hydrogenated, fractionated, then mixed or interesterified, de-acidified and well dried, for use at varied temperatures and for very long service.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #51 on: March 01, 2020, 03:40:36 PM »
Depending the alkyls, the trialkylamines of February 18, 2020 can have varied uses.
https://www.chemicalforums.com/index.php?topic=103039.msg362089#msg362089

It may not be as hydrophobic as hydrocarbons. I ignore if its combustion produces more NOx than a hydrocarbon. Slightly more efficient than an alkane, and if burnt with air, the engine power increases a bit but the consumption too. Mass-poduction is easy and efficient, the product is accurate.

From propene and n-butene, C+N~11.5 make a good rocket fuel and a jet fuel probably, with a good liquid range, flash point and self-ignition. Presently the C3-C4 fraction is torched at gas and oil wells, so using it as a fuel would reduce the CO2 emissions. The complete fraction could be fed to the reactor, the alkenes would react, the alkanes at the output easily separated and pyrolysed to reinject alkenes.

Gas and oil wells have no chemical processing presently. Using this fraction would need an ammonia and hydroamination unit at the well, or on a boat that collects the stored fraction, or onshore, or to transport the fraction overseas which isn't done up to now as butane is too cheap. Refineries have already an ammonia and hydroamination unit, propene is available but it serves, butene can be obtained from ethylene.

Ethylene and propene would target gasoline's molar mass but not the octane number. Isobutene might achieve a good octane number (or not, due to the amine) but with C+N=13, the upper end for gasoline. Maybe ethylene and isobutene achieve both. Alkylation is a cheap competitor.

n-alkenes around hexene would make a synthetic Diesel fuel emitting no fine particles hopefully, thanks to uniform autoignition temperature, lack of aromatics, high H/C ratio, and clean amine flame. Hexene is typically obtained from ethylene at refineries, so the fuel needs more processing than presently.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #52 on: January 10, 2021, 04:32:01 PM »
Chainsaws, forestry vehicles and others need biodegradable lubricants and hydraulic fluids that base typically on vegetable oils.

To obtain more varied viscosities, I suggest to saponify and re-sterify the oils with other alcohols. Already done with methanol to produce biodiesel, which is a (runny) lubricant. Glycol, erythritol, pentaerythritol... would vary the molecules' size. Mixes of very different oils, or wide mixes of acids prior to esterification, could make pastes or low-freezing oils.

About any fatty acid (or mix of) fits, cheap palm oil and palm kernel oil included. If they remain biodegradable, the acids or the oils could be saturated to resist oxidation better. Palm kernel fatty acids are shorter, keeping the oil liquid despite high saturation.

Could the ester of a very high polyol replace soap in lubricant grease? I don't quite know how soap acts here. This might reduce corrosion by any lubricant grease.

Maybe talcum is a good load for low-speed lubricant grease, as an alternative to graphite and molybdenum bisulfide.

I didn't check what is already done, as usual.
Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #53 on: January 10, 2021, 07:43:48 PM »
Amines reacting with polyols would make rocket fuels. Glycerine is cheap and abundent, other polyols too, dimethylamine and ethylmethylamine as well. The reaction seems trivial to me (but stinky and flammable): mix everything, heat strongly, remove the moisture. Compounds we could torch without remorse.

The depicted product of glycerine and dimethylamine is an isomer of pmdeta with identical performance. The product of 1,3-propanediol and ethyldimethylamine should have a nicely low freezing point but a good flash point. Higher polyols raise the flash point.

The big number of isomers should depress the freezing point, more so with ethyldimethylamine. The bulky dimethylamine branches possibly too.

Mixes of many compounds use to freeze at colder temperatures, and can even make eutectics. Mixing individual products can be more controllable. Mixing the reactants makes at once a huge number of products.

The compact molecules could be more runny than long chains with methyl branches.

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Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #54 on: May 22, 2021, 12:08:28 PM »
One very common heat transfer fluid is Dowtherm A, a eutectic of diphenyl ether and biphenyl that doesn't separate upon boiling.

I find it suboptimum to cool electronic boards:
  • One diphenyl ether supplier only guarantees 300ppm moisture, so I doubt a leak insulates well. Therminol, a copy of Dowtherm A, guarantees 300ppm in the eutectic.
  • Dowtherm A freezes at +12°C.
  • The 4mPa*s viscosity at RT limits the heat exchanges.
  • Flash point +113°C while some electronic components guarantee +125°C operation or more.
So I searched a few similar compounds to replace at least diphenyl ether. Most data here from Naca's report 1003 (in 1951 hence measured, many thanks)

Mp °C  Bp °C  mPa*s
=============================================
 -18   +273     3     1,1-Diphenylethane
 +25   +264     3     Diphenylmethane
=============================================
 -21   +271     6     1,1-Dicyclohexylethane
 -19   +253     7     Dicyclohexylmethane
  +4   +239     4     Bicyclohexyl
=============================================
 +12            4     Dowtherm A eutectic
 +25   +259    Sol    Diphenyl ether
 +69   +255    Sol    Biphenyl
=============================================


From these few properties, it seems that:
  • Dicyclohexylmethane could replace diphenyl ether, making with biphenyl a mixture that doesn't separate on boiling.
  • 1,1-Diphenylethane alone outperforms the eutectic of diphenyl ether and biphenyl.
  • 1,1-Dicyclohexylethane too.
  • Their eutectic is hopefully even better, including its viscosity.

1,1-Diphenylethane is known as a synthetic oil for capacitors and tranformers, so it insulates well. Mass-syntheses are known, as a by-product, or from styrene and benzene over a catalyst, and others. Hydrogenation would provide 1,1-Dicyclohexylethane if no better path exists.

Cycloalkanes store hence transport more heat than aromatics do. From Nist, 1858J/kg/K for 2-methylbicyclohexylmethane vs 1619J/kg/K for 1,1-diphenylethane (and 1560J/kg/K for Therminol). This more than compensates the density. The already mentioned branched alkanes are even better, around 2150J/kg/K: I believe these are a better development bet.

Marc Schaefer, aka Enthalpy

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #55 on: February 12, 2022, 03:01:40 PM »
2022 update to alkanes with a wide liquid range.

Once a rarity, 2,6,10-trimethyldodecane = farnesane is more widely available. Amyris didn't fly airliners with it, but alleged 1.75-4usd/kg in newspapers from biologic processes. They sold their farnesene plant to DSM and still market Biofene = farnesene and hemisqualane = farnesane. The process I suggested
  https://www.chemicalforums.com/index.php?topic=56069.msg349723#msg349723
might also make cheap farnesane from the resin of Ocotea caparrapi.

2,6,10,14-tetramethylhexadecane = Phytane would have a flash point over farnesane's +109°C but I see no mass production on the Web. Yamamoto synthesized farnesene from isoprene
  https://www.chemicalforums.com/index.php?topic=56069.msg297847#msg297847
and I hope geranylgeranene (phytene) can be obtained too, maybe over purified geranene (=dimer) to favour even oligomers. Starting from myrcene is doubtful, as it differs from geranene.

Polymerisation of isoprene is long done to mimic latex and gutta-percha. If feasible, quenching the reaction around the tri, tetra- and pentamers would be perfect. A mix of hydrogenated oligomers could even make eutectics.

Shortening isoprene polymers like latex, polyisoprene and gutta-percha would also give mixes of approximate tri, tetra- and pentaisoprene. Cutting a proportion of the double bonds at random locations suffices if feasible. The small difference with isoprene oligomers is irrelevant to most uses, provided pristane is absent. The hydrogenated alkanes remain asymmetric and have many isomers.

I had put hope in cheap myrcene dimer. The spontaneous dimer is alpha-camphorene. Its hydrogenation produces few isomers, so the freezing point shouldn't be magic. The hydrogenated head-to-tail dimer would be phytane, but how?

Offline rolnor

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Re: Produce a low-freezing rocket fuel
« Reply #56 on: February 12, 2022, 03:39:46 PM »
How about ozonides? Its easy to ozonolyze any unsaturated hydrocarbon, cheap.
I dont know how explosive longer-chain ozonides are. I have run cromatography and NMR on ozonides, they can be more stable than what is said in the literature. I guess they are high-energy compounds with the peroxy-type bond.

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #57 on: February 13, 2022, 07:07:53 AM »
LANL has studied camphoranes from myrcene for use in Diesel engines
  https://www.osti.gov/servlets/purl/1571622
they obtain a blend of varied camphoranes, a bit viscous, but not bad at cold.

[...] ozonolyze [polyisoprene]

Thanks Rolnor!

It's all a matter of cost. Most uses don't care about losing 1 or 2 carbons at the ends of the molecule. Ozone followed by zinc, hydrogen peroxide, then removal of the carboxylic groups by heat, could be cheap.
  https://en.wikipedia.org/wiki/Ozonolysis
About the explosion risk: I suppose the reactor can be designed to minimize the amount of unstable intermediate. Flow the alkene and the ozone in opposite directions, flow immediately the intermediate ozonide to the next pot.

Or could ozonolysis be done at room temperature, so the ozonide decomposes immediately? Obtaining ketones and hydrogen peroxide would be excellent.

Maybe the polyisoprene can even be introduced as a solid, and the oligomer leaves the reaction zone once it's small enough to flow.
« Last Edit: February 13, 2022, 07:28:44 AM by Enthalpy »

Offline rolnor

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Re: Produce a low-freezing rocket fuel
« Reply #58 on: February 13, 2022, 12:29:13 PM »
You missunderstood, I mean use the ozonides as they are, not cleaving them. They are stable att roomtemp. Then you dont need so much oxidant. Compare with triacetone triperoxide etc.
I dont know how stable ozonides are when stored though…

Offline Enthalpy

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Re: Produce a low-freezing rocket fuel
« Reply #59 on: February 13, 2022, 03:04:51 PM »
Oops, misunderstood indeed.

I have a bad gut feeling about ozonides as a rocket propellant. In such amounts, even nitromethane is ruled out because drops explode when falling on concrete from 100m height.

But ozonolysis to produce alkanes from latex seems interesting.

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