evildrome
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Etherification of Glycerine
Hi All,
I'm trying to work out a method of turning waste glycerine from biofuel into something that will burn as easily as heavy heating oil.
I'm thinking that if it can be turned into an ether with something cheap like methanol I'd have a chance at making something combustable (yes I know
glycerine burns but not well).
I had thought to react the glycerine with KI and react the product with potassium methoxide, recovering the KI (which is not cheap).
Was also thinking of HI but apparently its a controlled substance (bloody tweakers).
I have a sneaking suspicion I'd end up with some sort of epoxy.
I know that commercially etherification of glycerine is achieved at high temps & pressures with an acid catalyst (Amberlyst 15) but I'm looking
for a more bucket chemist method at sensible temps & pressures (ie 1 - 2 atm, <100 C).
Also I'd like to avoid reactions with lethal byproducts or intermediaries (like H2S).
I have a chemistry degree (ok, 30 years ago) but do not hesitate to get technical.
Cheeers,
Wilson.
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TheChemiKid
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I am not sure about an answer to your question, but HI can easily be made from KI and H2SO4.
When the police come
\( * O * )/ ̿̿ ̿̿ ̿'̿'̵͇̿̿з=༼ ▀̿̿Ĺ̯̿̿▀̿ ̿ ༽
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forgottenpassword
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<del>http://books.google.co.uk/books?id=TnU8SVNfFzkC&pg=PA87&lpg=PP1&focus=viewport&output=html_text</del>
http://books.google.com/books?id=TnU8SVNfFzkC&pg=PA87
http://pubs.acs.org/doi/abs/10.1021/ie201612t
http://digitalcommons.unl.edu/chemeng_biomaterials/18/
http://www.orgsyn.org/demo.aspx?prep=cv1p0292
[Edited on 10-2-2014 by forgottenpassword]
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: del;
non-restricted link]
[Edited on 10.2.14 by bfesser]
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TheChemiKid
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I cannot access the google book.
When the police come
\( * O * )/ ̿̿ ̿̿ ̿'̿'̵͇̿̿з=༼ ▀̿̿Ĺ̯̿̿▀̿ ̿ ༽
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forgottenpassword
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I can read the whole chapter. Try using a UK proxy.
[Edited on 10-2-2014 by forgottenpassword]
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evildrome
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Hi,
Thanks for the links. I'll respond in order:
1) Good results but requires isobutylene as feedstock. I suspect that the isobutylene would be pricey.
2) An excellent synthesis which I had already considered but discarded due to the highly toxic nature of DMS.
3) Requires isobutylene.
4) Produces Glycerol Dichlorohydrin which is an expensive chemical in itself but quite toxic.
Cheers,
Wilson.
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evildrome
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BTW I'm not wedded to making an ether.
If I could dehydrate the glycerine to propanol I could live with that.
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Dr.Bob
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The challenge is that if you think about cooking oil, the source of the glycerin, it does not burn real easily, even with 3 hydrocarbon chains on it.
When you make biodiesel, you are extracting the vast majority of the energy from the oil, leaving behind the glycerin, which can be thought of as
propane trihydrate, so it would take a lot of methanol and or energy to convert back to something that burns well. Since combustion does not really
care much about the bonds in the fuel, you would be better off to simply mix the glycerin with 3 equivalents of methanol and bun the mixture, as any
chemical steps to remove the water will require more energy to remove than will be recovered when burning the fuel.
So either find a way to burn the glycerin as is, or find a market for glycerin, as if there were any cheap and useful ways to convert it to something
better, the other 1000 biodiesel people would have likely found it. It's like the people who want to use hydrogen for energy and don't realize that
there are no ways to "Make" hydrogen that don't involve using some other source of energy, always at a lose of energy, due to the laws of
thermodynamics.
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forgottenpassword
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Increasing the oxygen/fuel ratio is the easiest way to improve combustion efficiency; but often the last thing to be considered! 
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evildrome
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Dr. Bob,
Good points. Glycerine's BP is a comical 290C which is why it doesn't burn well. Dissolving it in 3 parts methanol would certainly let you atomise it
which might make it combustible.
What may happen is that it still won't burn well but I have a waste oil fired siphon burner that burns heavy oils cleanly so I'll give it a go.
>forgottenpassword... Yes, adding more oxygen is always good but infrequently used because it either means pressurized air feed systems or
compressed oxygen, neither of which are cheap.
Cheers,
Wilson.
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Praxichys
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Perhaps cutting it back with a fraction of the biodiesel (assuing the anhydrous glycerin is soluble in it?) would allow it to work in a standard
heavy-oil burner at an acceptable level.
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Dr.Bob
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Quote: Originally posted by Praxichys  | | Perhaps cutting it back with a fraction of the biodiesel (assuing the anhydrous glycerin is soluble in it?) would allow it to work in a standard
heavy-oil burner at an acceptable level. |
Glycerin does not dissolve in the biodiesel, that is how you separate the two apart when the reaction is done. I have heard of biodiesel people
burning glycerin in a waste oil burner, but you have to heat up the burner first with another fuel and only burn a little glycerin at a time. Most
people just sell it as byproduct glycerin, which is used for a few things, including mixed with water to wet down dirt roads, since most places don't
allow oil for that use now. Dehydrating it to allyl alcohol or propylene glycol are two ways to make a product from it, but both are going to be
much easier in a larger scale. Maybe you can make solketal, the acetone acetal as well. It might burn well, but acetone is not cheap either.
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zed
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High temperature, and pressure, reactions aren't as difficult to achieve as you might imagine.
For some reactions, pumping your mixed reactants through a coil of heated, small diameter, stainless steel tube may suffice.
A pressure washer, or an airless paint sprayer, can be used to pressurize your reactants and force them through the tubing.
Multiple runs, might be required for complete conversion. Water removal between runs, can help to drive such processes to completion. Also note,
more than one product might be produced.
[Edited on 12-2-2014 by zed]
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Praxichys
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| Quote: Originally posted by Praxichys | | Perhaps cutting it back with a fraction of the biodiesel (assuing the anhydrous glycerin is soluble in it?) would allow it to work in a standard
heavy-oil burner at an acceptable level. |
They are not soluble but you do have a lot of waste oil on hand. Maybe make some oil into soap and use it to emulsify the two?
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Dr.Bob
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And note, if you just wanted to make a small amount of the glycerol trimethyl ether, just use diazomethane and it would work quick and easily. But
that would not be scalable, and as stated before, would require far more energy/reagents than the ether would provide back in value. The key
question is if you just need a small amount of the triether compound, or if you are trying to generate energy or value from glycerine. Those
questions have very different answers.
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Methyl.Magic
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Try to convert it to short ester such as acetate that is mush easier than etherification. Just mix glycerine with 3 eq of acetyl chloride and a base.
You can also dehydrate it to acrolein but this latter is really dangerous.... excedingly lacrymatory
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Dr.Bob
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Here is a link to a recent article on making useful chemicals from waste glycerol using "green chemistry". Link to a review with abstract at bottom.
Biodiesel may be a green fuel, but its production has a waste problem. Every year, producers of the alternative fuel create over a million tons of
glycerol worldwide, much of which goes to waste. Turning this side product into something useful and salable would help transform biodiesel into a
more profitable commodity. Some scientists have suggested creating acetylglycerols from the unwanted glycerol, since the compounds are used in many
consumer products. In a new study, chemists report a set of reactions that produces acetylglycerols in high yields using low-cost and abundant
materials (ACS Sustainable Chem. Eng. 2014, DOI: 10.1021/sc500006b).
http://cen.acs.org/articles/92/web/2014/02/Simple-Catalyst-P...
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deltaH
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One can apparently easily prepare glycerol carbonate in very high yields and simple reaction conditions using urea and glycerol with a zinc oxide
catalyst, see patent EP1156042B1, "Process for the preparation of glycerol carbonate".
Possibly the glycerol carbonate thus generated could be soluble in the biodiesel?
Such a process would generate large amounts of ammonia. One smaller scales one could theoretically bubbly this through an acid solution (sulfuric or
phosphoric, we wouldn't dream of nitric  ), to make fertiliser.
On an industrial scale, you could simply react the ammonia generated with CO2 to generate urea again, thereby effectively recycling your ammonia
internally. The overall process then becomes: glycerol + carbon dioxide =>=> glycerol carbonate + water, which I think would be pretty neat!
Hopefully I got that right, it's past 1am here and I'm going cross-eyed!
[Edited on 30-3-2014 by deltaH]
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Dr.Bob
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Here is a paper on that:
http://pubs.rsc.org/en/content/articlelanding/2011/dt/c0dt01...
So if you wanted glycerol carbonate,that might just work, but as a way to convert the glycerol to a burnable material, I fairly confident that you
would not gain as much more energy out burning the carbonate verses the glycerol, as you put into making the carbonate. There is a huge glut of
glycerin available, and it is already mostly oxidized, so it is hard to extract much energy out of it cheaply. Better to just figure out how to build
a special furnace designed to burn the glycerin and utilize it for process heat.
But here is another use, maybe you can market glycerol carbonate for that purpose:
http://www.biotechnologyforbiofuels.com/content/6/1/153
[Edited on 2-4-2014 by Dr.Bob]
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deltaH
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Interesting, nice finds Dr.Bob! I hope op get's a chance to see these.
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essbee
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I read a paper recently regarding the use of glycerol as a 'food' by some microbes who would convert it to ethanol as a by-product of their
metabolism.
Not sure where I found I,t but a Google search would find some stuff regarding this conversion, even a Company planning to do it commercially.
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BlackDragon2712
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| Quote: Originally posted by essbee | I read a paper recently regarding the use of glycerol as a 'food' by some microbes who would convert it to ethanol as a by-product of their
metabolism.
Not sure where I found I,t but a Google search would find some stuff regarding this conversion, even a Company planning to do it commercially.
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this one? http://aem.asm.org/content/74/4/1124.full.pdf+html
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