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Does anyone use Phosphoric Acid for acid stage?
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quote:
Originally posted by Biotom:
keelec
-the flake koh I use is 91%, the other 9 % is moisture. in the acid stage, the sufuric acid is 93% with the remainder being water. We have to be carfull with the amount of water that is carried into the ae process, this reaction is much more sensative to water than the transesterfication process. The ae process will only esterfy 5% of the ffa's with a water content of 5% by weight (ISU report on easerfication) Tom
Tom,

I was surprised a while ago when I read that people were actually having good results with aqueous NaOH.

In reality, you tend to use so little NaOH/KOH, that using an aqueous solution only adds a few ml water/gallon oil. Some producers believe this is tolerable.

http://www.biodieselgear.com/d.../AqueousCatalyst.pdf

http://biodiesel.infopop.cc/ev...9605551/m/2631031032
http://biodiesel.infopop.cc/ev...9605551/m/4761097712
http://biodiesel.infopop.cc/ev...391089391#5391089391

Back to the point at hand.

Here is an interesting article that popped up:
http://www.journeytoforever.or...odiesel_glycsep.html

It appears as if they are doing "normal" NaOH/KOH processing.
Then following it with treating the Glycerin layer with phosphoric acid which separates the FFAs from the Glycerin.

They don't discuss trying to acid esterify the FFAs.
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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keelec
-yes, adding phosphoric acid to the byproduct, in an amount determined by titrating the bp, is used to reclaim the salt, glycerin, and ffa's, the method discribed at jtf does work, but I found it very expesive for the amount of glycerin that is reclaimed. If you want to see their esterfication process, look under the fool proof method. but as many here know it does not work!
-the base transesterfication process, can handle some water,more than the AE treatment, so it may be possable to use the liquid caustic with the right wvo conditions,ie very dry,low ffa content. Seems to me though if you bring more water into the reaction more soap is produced. Thats the main reason I don't think it would work after the AE process. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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FG
-OK I tried it, but phosphoric acid didn't work at all, starting T 8 ending T 8.5 I used twice the acid amount that I use for sulfuric acid, total time 6 hrs, but I will let the sample sit heated over nite then see if there is any change. the remainder of the batch,160 ltr is at T 1.5 using sufuric acid. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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One note that came up earlier was to avoid mixing Strong Oxidizers with Glycerin.

http://biodiesel.infopop.cc/ev...53106871/m/890103002

So, no Perchloric Acid, Nitric Acid, etc around Glycerin, and probably not with the raw vegetable oil either.

The explosion above discussed Sulfuric Acid + Glycerin. It was a bit confusing, but I thought that the Sulfuric Acid was also able to act as an oxidizer, but I'm not sure if it can do it alone.
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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George this might help phosphoric_acid.pdf
 
Location: Nimbin Australia | Registered: December 04, 2007Reply With QuoteReport This Post
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sinbab
-good read.

-FG
-24 hrs has passed and nothing has changed so the liquified phosphoric acid doese not work. In flake or powder form it my work. strange thing though, there is 1/2" of foam sitting on top of the wvo, looks like soap. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post



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Originally posted by Fuzznag:
FuriousGeorge
I did not say I have never heard of it, I said the plants I have worked with don't use it mostly because of cost. But also because the water does cause some issues in the reaction, more so than using sulfuric. So sulfuric is cheaper and easier to use from what I have seen.


I gotcha. I was genuinely questioning the accuracy of the source, and fully prepared to take your word for it, while probably sounding a bit sarcastic unintentionally.

quote:
Originally posted by Biotom:
-FG
-24 hrs has passed and nothing has changed so the liquified phosphoric acid doese not work. In flake or powder form it my work. strange thing though, there is 1/2" of foam sitting on top of the wvo, looks like soap. Tom


Thanks for testing that out for me! I wonder what that foam is. I don't think it can be soap, can it? Don't you need a base + oil + water to make soap? Could the foam on top be a less dense layer of MeOH/Water/H3PO4 solution? Since the reaction didn't happen very little water would have resulted, potentially making the layer more MeOH than H20 to the extent that it is less dense than the oil, and floats..

I thought this thread had died, so I posted a thread here about how much water is produced in the AE process. It kinda morphed into this same discussion. As Double D explained, and as several others have said here, H3PO4 is a weak acid, so it doesn't ionize much as a catalyst.

I don't know how much weaker it is, but let's say it's 1/3 as strong as Sulphuric Acid. That would mean you need 3 times as many molecules (I presume) of H3PO4 to to have the same effect. I believe it just so happens that a molecule of Sulphuric Acid weighs about as much as a molecule of Phosphoric Acid, so you may need 3 times as much by weight (or more).

On top of that it would probably need to be in solution with MeOH, not H20, since as others have stated, the AE process is much more sensitive to water than TE.

Thanks again for testing that out, and thanks to everyone else who replied. I'm still reading through a lot of the info, and I'll update later if needed.
 
Registered: March 16, 2008Reply With QuoteReport This Post
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FG
-still keeping an eye on the sample, the foam has turned into a semi solid layer, surounded by clear fluid probably the methanol. The T has not changed. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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quote:
Originally posted by Biotom:
FG
-still keeping an eye on the sample, the foam has turned into a semi solid layer, surounded by clear fluid probably the methanol. The T has not changed. Tom


I've done some more research and if I understand this correctly it *should* work, but maybe only if the H3PO4 is anhydrous.

Basically, a catalyst just speeds the reaction. That fact that it didn't work suggests that maybe the water in the H3PO4 plus the water that was created was enough to slow the reaction to the scale of days or weeks. Maybe it stopped entirely.

Is it possible that it did work and the T is high now because of all the Phosphoric Acid is what is making the solution acidic? You said you used twice as much as you would have for Sulfuric and T went up not down. I'm not sure if this is a possibility.
 
Registered: March 16, 2008Reply With QuoteReport This Post
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There are lots of substances that can be used as a catalyst.
Lead and Zinc acetate is supposed to work as a catalyst for transesterification and esterification. The study I read used high pressure and temp. I tried at atmospheric pressure and low temp and got nothing?.
So phosphoric might work if the conditions are right.
 
Location: Nimbin Australia | Registered: December 04, 2007Reply With QuoteReport This Post
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