[supersecondrow]

I'm trying to make a fuel gel using the by product of biodiesel production glycerol. I'm finding difficulty in forming a good gel. If I mix acetate with glycerol it won't form a gel when I add ethanol. If I make the gel first the glycerol just makes everything watery. Any help?

[Jose_Matheu]

Hi. Have you try Carbopol. Add 1% Carbopol to the mixture of glicerol and water, which is mainly what you end up after esterification of oils to produce Biodiesel. After that add ethanol and add 4 ml of triethanol amine. I was looking for something similar and it worked well.

[CaptainPanic]

A gel requires a polymer which is crosslinked.
All glycerol will do is increase the viscosity. Something which is very viscous is not yet a gel.

A gel is not a newtonian liquid. Glycerol is a newtonian liquid, and ethanol+glycerol will also behave as a newtonian liquid. (Can anyone comment on this last remark? I could not find a reference, and I'm not 100% sure about it).

[Theophrastus]

I'm not quite sure, but similarly, I agree with captain panic, in that while glycerol may increase the viscosity, but a cross- linked polymer is required. Furthermore, I was recently interested in glycerol's (or glycerine's, as its more commonly known) uses, and I believe I read something regarding that if it is not combusted in a particular fashion, it will give off acrid fumes, which I assume are generally an unwanted by- product, however of glycerine's combustion, I really know little concrete knowledge of. Some justification or reconciliation by others is required, I suppose. Any help?`

[UC]

Theophrastus said:

I'm not quite sure, but similarly, I agree with captain panic, in that while glycerol may increase the viscosity, but a cross- linked polymer is required. Furthermore, I was recently interested in glycerol's (or glycerine's, as its more commonly known) uses, and I believe I read something regarding that if it is not combusted in a particular fashion, it will give off acrid fumes, which I assume are generally an unwanted by- product, however of glycerine's combustion, I really know little concrete knowledge of. Some justification or reconciliation by others is required, I suppose. Any help?`

You do have a point. Glycerol undergoes dehydration to generate acrolein, which is quite toxic and oxidizes to acrylic acid, which is also toxic. I suspect that as a gel, it would not be a clean burn at all. Probably rather sooty, since it isn't being force-fed oxygen to complete the combustion. If you were to solvate it in methanol and spray the mix into a burner system, sure, you could get it to burn completely without toxic fumes.

[leonardon]

Someone have an idea of how lowering the ignition point of glycerol?
I'm thinking mixing ionized glycerol with ozone...

Regards.

[UC]

leonardon said:

Someone have an idea of how lowering the ignition point of glycerol?
I'm thinking mixing ionized glycerol with ozone...

Regards.

*directs you toward a chemistry book and demands that you make sense*

[Theophrastus]

How will oxidizing glycerol, significantly lower its boiling point?

[hermanntrude]

what's the name of the acid formed by oxidation of glycerol anyway? it may have a low boiling point because of dimer formation

[UC]

hermanntrude said:

what's the name of the acid formed by oxidation of glycerol anyway? it may have a low boiling point because of dimer formation

Well, dehydration gives acrolein (acrylaldehyde) by tautomerization, and the oxidation product of that would be acrylic acid. Without dehydration there would be so many hydrogen bonding groups available that the boiling point would probably exceed decomposition temperature.

Ozone would just chew glycerol up into CO2 and formaldehyde.

[hermanntrude]

not what I meant. I meant if you turned all the hydroxy groups into carboxylic acid groups, what would you have? it's basically citric acid with one hydroxy group removed.

[UC]

hermanntrude said:

not what I meant. I meant if you turned all the hydroxy groups into carboxylic acid groups, what would you have? it's basically citric acid with one hydroxy group removed.

That would involve magically adding carbons :p

[CaptainPanic]

hermanntrude said:

not what I meant. I meant if you turned all the hydroxy groups into carboxylic acid groups, what would you have? it's basically citric acid with one hydroxy group removed.

Citric acid is , while glycerol goes by the formula of

Citric acid (wikipedia picture):


Glycerol (wikipedia picture):


On the glycerol molecule, you cannot completely oxidize all 3 -OH groups (to carboxyl), simply because the middle -OH group is attached to a carbon which itself is again attached to two carbons, and can only form a double bond at most with the oxygen (as in acetone).

The most oxidized product of glycerol would be something like dicarboxy-formaldehyde, but I can't find anything about it, and I wouldn't be surprised if it is not stable and will instead form formaldehyde and 2 CO2.
My first guess here is that glycerol doesn't want to oxidize any further without falling apart.

But anyway, the reason we're investigating this (to lower the ignition point through oxidation) is nonsense. You shouldn't be partially oxidizing a fuel. It lowers the heat of combustion. And the use of small molecules, as mentioned before, is not going to make a gel. So, unless we think this is more interesting, we should return to the original topic, which is either: "how to make a fuel gel", or "how to use glycerol as a fuel"?

1. how to make a fuel gel?
- Already answered: get a crosslinked polymer in sufficiently high concentrations.

2. how to use glycerol as a fuel?
- I found that glycerine acetate is a fuel additive.
- Alternatively, you might have to remove the -OH groups (hydrotreating or hydrocracking or something - not sure it's worth the effort, and apart from the fact that probably none of us have the right catalysts, it is surely not something you want to try at home).

This post has been edited by CaptainPanic: 22 April 2009 - 09:01 AM
Reason for edit: removing mistake, adding answers to the original question(s)

[UC]

CaptainPanic said:

The most oxidized product of glycerol would be something like dicarboxy-formaldehyde, but I can't find anything about it, and I wouldn't be surprised if it is not stable and will instead form formaldehyde and 2 CO2.
My first guess here is that glycerol doesn't want to oxidize any further without falling apart.

http://en.wikipedia..../Mesoxalic_acid

less oxidized products include dihydroxyacetone (sunless tanning products) and glyceraldehyde (important compound of you're stereoisomer-savvy)

but yes, both are irrelevant to the discussion. I think glycerol would be more far more valuable as a feedstock than as a fuel.

[CaptainPanic]

UC said:

http://en.wikipedia..../Mesoxalic_acid

less oxidized products include dihydroxyacetone (sunless tanning products) and glyceraldehyde (important compound of you're stereoisomer-savvy)

but yes, both are irrelevant to the discussion. I think glycerol would be more far more valuable as a feedstock than as a fuel.

Thanks for the link to wikipedia... cool to see that this compound exists, and nice to know the name: mesoxalic acid :D

Glycerol, if clean, used to be quite valuable... but the reason people are interested to use it as a fuel is that the glycerol market has been ruined by the biodiesel producers who have loads of glycerol as a by-product. Glycerol is now almost worthless.

Here's a list of "things you can do with crude glycerol (unpurified glycerol from biodiesel)" (warning: .PDF).

Alternatively, you can add it to anaerobic digesters, (you also avoid the glycerol purification). The bacteria in those digesters don't mind some glycerol, and they'll produce methane with is a useful product. Still, we're talking about cheap fuels here, it's not exactly turning lead into gold yet.

[leonardon]

Glycerol byproduct of biodisel is dirty for food, bettr as fuel.
I was thinking to add ozone because nitration add also oxygen (and is proven it work well), but there is the "N2 that is not good because improve NOx yeld during combustion.
Glycerol Acetal need acetal aldehydes for its sinthesys.
Perhaps mixing it with other biofuels is the better way to burn it.

[CaptainPanic]

leonardon said:

Glycerol byproduct of biodisel is dirty for food, bettr as fuel.
I was thinking to add ozone because nitration add also oxygen (and is proven it work well), but there is the "N2 that is not good because improve NOx yeld during combustion.
Glycerol Acetal need acetal aldehydes for its sinthesys.
Perhaps mixing it with other biofuels is the better way to burn it.

I don't understand. You want to add ozone to glycerol? I think it will just burn.

I recently found out about a company that uses (purified) glycerol to feed a steam reformer to form synthesis gas (H2 / CO) which is then used to form bio-methanol.
I hope I understood the process correctly, because intuitively I'd expect that you could go for a more direct reaction from glycerol to methanol, perhaps in 1 step.

Oh, while I'm writing a post in an ethanol-fuel-gel thread anyway... This particular thread was sort of hijacked and became a glycerol thread. But the other ones weren't. Can anyone explain me why we have 3-4 different ethanol-fuel-gel threads? Why do people want this gel fuel? ...

[leonardon]

Someone know about Gly-Clene?
How is possible to make a fuel only by add very few additive to glycerin?

[CaptainPanic]

leonardon said:

Someone know about Gly-Clene?
How is possible to make a fuel only by add very few additive to glycerin?

Gly-Clene is a brand-name, not a chemical. there is only 1 company who make the stuff, and they seem to keep the process a secret.

I don't know what "GlyClene" is. None of the websites I find through Google are any good.

Typically, the websites are making (big) mistakes. In other words, they're writing scientific gibberish...

Have a look at the 3rd paragraph of this one:

Quote

There is currently enough glycerin produced in the U.S. alone for Gly-Clene to produce 27,000 megawatts of electricity per day or over 8 billion megawatts per year without even adding steam turbines to take advantage of the excess heat produced by the turbines.

That means nothing. You cannot have megawatts per day. That is [energy per time per time].

I wouldn't worry too much about this process. If they patent it, and it's successful you will hear about it anyway.