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No methanol esterification idea/experiment
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Hi all.

After reading through all 70 pages of that long thread for the first time I had an idea that I'm not sure anyone's tried yet. If it's already been tried then I apologise for not searching around thoroughly enough.

As we all should know, the AE stage combines FFAs to methanol creating water and FAMEs in the process. This esterification process is bidirectional and to ensure the equilibrium is pushed towards the FAME side of the equation, we need to either pull the produced water out and/or use an excess of methanol.

My thought is what if we could reduce the methanol required in the AE stage, by using the existing mono- & di- glycerides in WVO, as the alcohol? Combining FFAs to the glycerol backbone can be done in one AE stage, then after removing the water from that reaction, you can do a methanol AE stage to combine the rest of the FFAs.

The question is whether the amount of di- & mono- glycerides in really, really, REALLY bad oil is in enough excess to push the equilibrium towards the right (even a little bit). Removing the water from the WVO is already an important first step. All that would be needed is a bit of sulfuric acid to catalyse the FFAs to the di- & mono- glycerides, a bit of heat and mixing, and a titration to see which way the reaction went.

Remember that the esterification process is bidirectional, so adding sulfuric acid catalyst to oil that is already low in FFAs will probably increase FFAs!!

Any thoughts?
 
Registered: September 29, 2010Reply With QuoteReport This Post
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interesting first post...

welcome to the forum...
 
Location: Ontario | Registered: April 13, 2009Reply With QuoteReport This Post
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One comment...

As I understand Raw Glycerin is actually a mix of Glycerin, FFA, Sodium or Potassium, methanol, and other impurities.

People have reported that acidifying the Raw Glycerin (neutralizing the Sodium salts), will cause the FFA's and glycerin to separate out.

If your theory was correct, then one should be able to acidify the raw glycerin, mix, and probably heat a little bit to try to force the FFA's back to monoglycerides which could then be transesterified.

Of course, it is possible that the monoglycerides would not separate from the FFA's as much as the glycerin would so there might be benefits of using monoglycerides instead of raw glycerin.
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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quote:
esterification process is bidirectional, so adding sulfuric acid catalyst to oil that is already low in FFAs will probably increase FFAs!!

Andy
-Ive been doing AE for many years,all my biodiesel batches start with AE. what you are saying here does not correspond to what actually happens, If I have wvo that T's at 4 and add 1ml of sulfuric acid it will T at about 6, not as a result of any reverse reaction (creation of more ffa), but as an indication of how much more caustic that is required to neutralize the acid.
-If you read buckeyes post in the ae thread you will note, if the wvo is dry and sufficient heat is applied AE happens very quickly with a minimun amount of methanol. Methanol used in ae is not wasted, it remains in the batch for base processing. IMO it is base processing that requires the exess methanol to push the reaction. 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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chemically I don't mono and di's are alcohols. they're emulsifiers as such they would have to have a polar and non polar end. they like water on one end but not the other. the non water end likes oil.

interesting thought, but I don't think it'll pan out.

there is another way to process bad oil that I've heard about but never tried.
make it into soap first. water, oil, caustic..->soap..
mix the soap with acid. settle. you get FFA, water, and a salt.
then process the FFA.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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quote:
Originally posted by Biotom:
-Ive been doing AE for many years,all my biodiesel batches start with AE. what you are saying here does not correspond to what actually happens, If I have wvo that T's at 4 and add 1ml of sulfuric acid it will T at about 6, not as a result of any reverse reaction (creation of more ffa), but as an indication of how much more caustic that is required to neutralize the acid.

Yep. I had little doubt that adding sulfuric acid to low T oil will increase T (increase FFAs).

What I'm interested in is whether adding sulfuric acid to very, VERY high T oil (around the 70-80 mark) might actually lower it, based on the assumption that once you pull the water out, the equilibrium has shifted. I don't have any oil that T's that high to try it out though.

I think I read a couple times in that 70 page thread that some people weren't draining the quantity of methanol/acid/water they thought they calculated, and my thought was that FFAs could be combining back to the di-, mono- glycerides.

Yes I do understand that di-, mono- glycerides aren't "alcohols" as such, but they do have two/one -OH tails to spare, and if there isn't any water bonded to them (ie. you've removed all the water from your bad oil), then what's to stop FFAs being reconnected via acid catalysis? The main thing which will prevent them reattaching, as I eluded to in my original post, was that you'd need to have an excess of the di-, mono- glycerides to push the reaction to the right (ie. really, really, REALLY bad oil). Unfortunately there's no way (apart from GC) to determine the amount of di-, mono- glycerides in the first place.

But I was hoping that someone with T80 oil might be able to try it out in a mini-batch or something Smile
 
Registered: September 29, 2010Reply With QuoteReport This Post



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I think Biotom's note was that FFAs are typically a small percentage of the total triglycerides.

So your acid esterification step would use a proportionally small amount of methanol compared to the entire batch size.
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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adding acid to the oil doesn't create FFA's it does raise the titration..

I think you look through the 70 page sticky you'll find that water is created during the AE process.
so even if the oil starts DRY..water is created..

for the amount for draining its almost always around 1/2 the methanol volume..of course the higher the titration the amount is slightly more..but not much..

for the amount of methanol
10-12% of the oil volume is typical, but this is almost always too much. if I recall its T/6 for ml of methanol per liter..so at T60 you hit the 10% mark..

keep the questions coming..good thinking.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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combining ffa's back onto a glycerin group creating mono and diglycerides is called glycerolysis. if you turn all your ffa's back into oil, you might as well just do the base stage reaction. however it takes a lewis acid and high temperatures to get high conversion rates...
 
Registered: June 07, 2008Reply With QuoteReport This Post
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new to here so bear with me. I have got some very off spec WVO biodiesel. the FFA is in the 20's with 0 soap and a moisture of 1.01%. I have all the testing capabilities (gc). Just a few questions. Is the moisture to high for AE? What is the best method of AE for me to use. I am currently using the Iowa State Method. Since this is bad biodiesel and not pure WVO feedstock I am not doing the base after the acid. My acid number is really high after batching. The best number I can get is around a 2 ffa. Any help or ideas would be great.I have a gc test running now and will get back with you on the results. thanks
 
Registered: November 17, 2010Reply With QuoteReport This Post
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Hey there.

I'm beta testing a new Esterification Calcualtor on my website http://b100research.com/resources

If you contact me directly I will give you the password to get into the Beta Testing section. I think that this tool will be able to help you fix your AV issue.


B100Research.com
 
Location: CO, CA, KS, or FL | Registered: January 17, 2009Reply With QuoteReport This Post
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