Dear friends;
My previous thread was given as A NEW CONCEPT on ESTERIFICATION PROCESS of FFA. http://biodiesel.infopop.cc/eve/forums/a/tpc/f/629605551/m/1211010281

In summary, I was trying to produce the mono-glyceride from low lipid source like acid oil of soapstock. The name of chemical reaction is glycerolysis.
“FFA+Glycerol <---> monoglyceride+Water”
I set up a small lab unit and I made experiments. Results are given below

- 1100 gram acid oil of soap stock PH: 5,01- dark clear Brown- liquid at room temp.
- 258 gram crude glycerol of biodiesel PH: 10,3.
- PH of mixture of reaction – 5,7
- Temperature : 180 C
- Time : 8,5 hours
- Vacuum : 160 mmHg after 95 minutes and 180 C.
- N2 gas purge with vacuum
- No catalyst.
Results :
1120 gram Monoglyceride : dark brown, semi-transparent – liquid in 180 C but it suddenly starts to solidify in 135 C - very viscous in room temperature like Chocolate Puding.
Water : 47 gram
Distillate : 3 ml clean-yellowish oil.
Titration
At the begining -150 ml (tickel method- 1 gram NaOH in 1000 ml pure water)
After 315 minutes-20 ml - 375 minutes 9 ml. At the end of reaction titration was 20 ml. titration was measured for 1,3 gram sample from reactor.

My Consideration
1- collected water is very low and frustrating.
2- 3 ml clear yellowish oil is very promising. and it may be a hope–light
3- Main product, Dark Brown, semi-transparent and sticky and viscous like chocolate puding. I does not seem the monoglyceride.
4- I think that main product is neither acid oil nor glycerol.
I am gonna attach some photos of products in the forum later.

Questions;
1-What is the color of natural monogliceride? Like chocolate puding?
2-Why did titration increased at the end of reaction?
3-Is reaction temperature, 180 c, as enough as to foward reaction right side?
4-Why collected water is so low.
5-What kind of catalyst do you propose to reaction for sake.

I forgot saying the Density of final product is 0,8808 gr/ml.

erdem ozcan,
I suspect that the pH of the initial reaction wasn't low enough. It is very possible that you polymerized your ffa's into something like an alkyd gel. That is to say the multiple double bonds in the ffa chains crosslinked to form a gel. At the temperatures (180 C) you ran the reaction with the vacuum it wouldn't be at all surprising.
You might want to repeat the reaction adding enough acid to reduce the pH to 0-1, run the reaction at a lower temperature and purge with nitrogen gas (prescrubbed to eliminate oxygen) but don't apply full vacuum (just enough vacuum to move the nitrogen through the system).
Is it possible that your distillation condensor/system couldn't fully recover the water vapor. Try a cold finger using dry ice/ acetone behind or instead of the condenser.
Finally, try using purified (purchased) glycerol instead of crude biodiesel byproduct. When you are convinced that you can sucessfully make monoglyceride with the pure glycerol then try crude glycerol.
The first rule of bench chemistry is to make a sequence of expt's starting from the most well defined situation then move toward the desired end one step at a time.
Good luck and let us know how it goes.

I think I have more questions than answers....

1) Why process in a vacuum? I can see wanting to purge the oxygen, but not why to use a vacuum.

2) Were you trying to remove the water as it was produced?

3) Is cost the motivation for not using a catalyst? A little H2SO4 is probably a lot cheaper than processing at those temps for that length of time

To guess at answers for your questions:

1) I don't think monoglycerides have a definite color in this context. I'd guess with the natural acid and heat it'll be a very dark color.

2) Just a WAG, but water + heat + VO => FFA's breaking off.

3) No idea. I've lowered the FFA's from acidulated soap from 50+ KOH to < 10 by adding a ml/L of H2SO4, some glycerine from the split byproduct, and 300 degrees F. If you have an acid catalyst that's way hotter than you need.

4) I can't even guess without a much more detailed description of the test setup.

5) H2SO4 in 95% or better concentration is the standard catalyst for acid esterification. At least that's what keeps popping up. I'm not chemist enough to say whether HCL or phosphoric acid could be used instead; I'm pretty sure there's no economic case to be made for either. And I hate working with HCL

HTH,

--- David

Erdem_ozcan,
After thinking about your low water recovery I wonder how did you introduce the nitrogen into the vessel and did you agitate? I know from pervious experience that without good mixing it can be very difficult to remove traces of water (or other solvents ) from a reaction without either bubbling the purge gas through the mixture or mechanical agitation.

Dear Rick G;

I added a few photo for monoglyceride samples in the different perspectives. I think it would help us on desicion making process.

I woulk like to suprisingly say that I made fame raction to measure reactivity this product which it's photo given attached. (440 gram Monoglyceride-25 % MeOH and 5,02 gram NaOH)
I have got three phase. light brown-Upper is absolutely methlyester, white-Middle is unknown ???? dark brown-Lower is just glycerol.

best regards for precious comments

This message has been edited. Last edited by: Shaun,

finalproduct1_copy.jpg (38 Kb, 44 downloads)

Second JPG

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finalproduct3_copy.jpg (31 Kb, 31 downloads)

distillate jpg

This message has been edited. Last edited by: Shaun,

distillate1_copy.jpg (26 Kb, 31 downloads)

photo for reactiblity of monoglyceride for fame reaction. You will see three phase.

This message has been edited. Last edited by: Shaun,

bdproductionthreephase_copy.jpg (24 Kb, 47 downloads)

Dear Rick G;

Agitation is about 200 rpm. I have 1,5 lt-four neck reactor. Nitrogen of 100 ml/hr is introduced to reactor in last two hour of 8 hour reacton time.