Aviation Fuel

[nigelb]

Just been reading an article on jet fuel made from waste including food and vegetable oil. The article says that in order to turn wvo and svo into fuel suitable for jets its basically the process that we use plus "an extra step" making the finished product prohibitavly expensive.

Anybody know what this extra step may be?

[Julian]

Something to prevent it solidifying at 30,000 feet I'd guess.

[WesleyB]

Easy question . Aviation fuel in jets means kerosene . Kerosene is hydrocarbons without oxygen atoms attached to them  .  So hydrogenation of free fatty acids produces hydrocarbons without oxygen atoms in them .  You take platinum or palladium finely divided solid catalyst in free fatty acids  add hydrogen gas to get fatty alcohols .  Then in perfectly dry  hydrocarbon solvent add lithium metal stoichimetrically  to fatty alcohols and hydrogenate the product with hydrogen gas to get synthetic kerosene , for a lot of money per litre .  There's another way using lithium aluminum hydride in tetrahydrofuran (solvent) plus perfectly anhydrous biodiesel to get the alcohols .  Then hydrogenation (reduction) with lithium and addition of hydrogen gas to produce hydrocarbons from biodiesel .  The hydrocarbons can be cracked to make shorter chain high octane aviation fuel for old type propeller air plane engines .  The chemistry works on paper but it's more expensive than distilling it from fossil fuel petroleum .

[neisel]

https://www.bbc.co.uk/news/science-environment-56408603

I'm struggling getting my head around how "The authors of the new study say the fuel cuts greenhouse gas emissions by 165% compared to fossil energy" (as well as just about every word in Wesley's post ^^^).

[nigelb]

Thanks Wes. A diffinative an answer as I've seen anywhere.

[WesleyB]

Another process for making hydrocarbons (kerosene) from biodiesel uses phosphorus .  That's the stuff that burns when in contact with the oxygen in air . The fatty acid molecule has two oxygen atoms in it , plus 14 , 16 , 18 or  20 carbons in a chain bonded to each other . There are many hydrogen bonded to the chain of carbons also . As best I understand it phosphorus preferentially bond to the oxygen atoms in the free fatty acids then adding hydrogen gas pushes the phosphorus oxide off the fatty acid molecule leaving a hydrocarbon (carbon+hydrogen) . That's like synthetic kerosene or maybe it's called petrol .   Sodium metal may be used instead of lithium metal in the procedure I already described . 

[photoman290]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

[Tony]

Fractional distillation will be the extra step.  Biodiesel from waste oil produces a wide spectrum of hydrocarbon chains, the military and aviation industries recognise how this makes the fuel properties extremely variable and fix it by fractional distillation.

[nigelb]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

It'll make for an interesting afternoon😁

[Head Womble]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

That'll be the bucket and drill mixer brigade 

[Jamesrl]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

If a plastic bucket wont do will a galvanized one be OK?

[Julian]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

If a plastic bucket wont do will a galvanized one be OK?

I'd have thought leather buckets were more of your generation.

[Jamesrl]

phosphorus, lithium, and hydrogen. hope no one decides to make that in their plastic bucket in the garage.

If a plastic bucket wont do will a galvanized one be OK?

I'd have thought leather buckets were more of your generation.

My first bucket and spade as a child was made of stone.

[WesleyB]

There's not much being posted , so ...  Aviation fuel can be made from vegetable oil in a prohibitively expensive way by electrochemistry .  I  have a book that  includes the on paper reaction .  Free fatty acids are obtained from vegetable  oil , then mixed with acetic acid in excess .  Carbon dioxide is produced and kerosene when a direct current of electricity is passed through the material .  I tried doing it once , without success .  I believe wax and ethane are also produced .  This electrochemistry step might be the additional step making aviation fuel from biodiesel .  I think it was called the Kolbe Electrolysis .  It's an old electrochemistry reaction from the middle eighteen hundreds .  I have not calculated how much it might cost to make a gallon of synthetic kerosene this way .  The electrodes in this reaction ought to be a non-reactive metal like platinum .  A copper electrode might work but it would probably corrode due to the electric currect flow .

[WesleyB]

I didn't give a reference for an extra step to make aviation fuel (kerosene) from biodiesel via the Kolbe Reaction (electrolysis)  .  A reference to it is Organic Electrpochemistry , 2nd edition  , edited by Manuel M. Baizer and Henning Lund , Published by Marcel Dekker , Inc. New York copyright 1983 printed in USA .The mechanism of the Kolbe Reaction is on page 441 and other pages .  But the electrolysis of organic acids was being done over 130 years ago .  I should have included that reference when I described it earlier .  A problem I had with electrolysis of free fatty acids and biodiesel was getting the direct current electricity to flow through the liquid using a 12 volt battery charger .