Hi,
I was wondering if anyone knew of a method to reduce Polymerization during the creating of Canola Biodiesel. I have heard that many Canola Biodiesel processers perform their reactions at lower temperatures (50-55 degree celcius), which would be considered low in terms of commerical production of Biodiesel. Would lower temperature improve not only the Polymerization that could occur, but help drive the reaction forward more so then high temperature? Is there any reason to think that processing canola at higher temperature would negatively impact the Monoglycerides in the Biodiesel?

Ryan

regger
-processing at temps higher than those you stated can cause the back reaction creating monoglycerides. When methanol is heated beyond 64C it vapourizes out of the mix causing an imbalance in the chemisty, unbalanced chemistry is always followed by a reverse reaction to bring the mix back into balance.(so I am told) 50C is a common temp for commercial producers.The only thing I have heard about processing canola oil is that it contains 11% poyunsaturated fat, this component is harder to transesterfy than the other fatty acids. I have found that using the base/base process at 95/5 works best for this oil. the extra methoxide in the first base stage helps to push this stuff to conversion. Soybean oil has the next highest level of polyunsaturated fat, at 8% other oils have from 1% to just a trace amount. Tom

quote:

Originally posted by Biotom:
When methanol is heated beyond 64C it vaporizes out of the mix

Actually neutral's experiments have shown long ago that the boiling/vaporization point of methanol when mixed with lye and vegetable oil is considerably higher than 64C--

I routinely process at 70C--

Neutral--

"My experiments show that you have to raise the temperature of the vessel above 77 deg C before that happens and you won't be going anywhere near that temperature."

http://biodiesel.infopop.cc/ev...=374103682#374103682


ReM

ReM
-??? how can that be!!! methanol is methanol, we have disolved the caustic with it,and mixed it into the wvo, but that does not change the fact that it is methanol I see methanol settling in the top of my site tube at much lower temps than that! Recently After a discussion on another thresd about methanol bioling off in the ae treatment, I removed the bung on top of the processor and put two fingers into the tank, it was dripping with methanol. Temp 65C or 150F I don't understand Tom

Biotom,

There is no doubt that some or a lot of the methanol will vaporize at 150F.

From what I have read here when you mix things together with different boiling points they try to average out e.g. the boiling point of methanol is around 150F, but the boiling point of glycerine is somewhat higher -- I think the boiling point of the combined is somewhere between 150 & 212F. Someone had a chart once that showed that you really have to heat the glycerine byproduct up well beyond 150F to completely remove the methanol.

That is a well known phenomenon, that is the reason when distilling methanol it must be agitated or sprayed, when it the mixture is sprayed the components are exposed to the heated atmosphere in the head of the vessel which makes it easier for the methanol to vaoporize.
There will always be some methanol flashing off the surface in the head of the vessel, that is what you see in your sight tube or feel (very,very bad idea) through your bung hole.

Tom, your really should refrain from reaching in your bung hole. Its just not safe..

Now we are getting somewhere! don't put fingers in your bung hole! the methanol that is BOUND to the water in the gycerne is for sure harder to recover, this takes more heat. The point I was trying to make is that to get a chemichal reaction that we want, we have to balance the chemistry (the right amount of methanol, the right amount of caustic and heat.) in a way that this reaction takes place. now if the mix becomes unbalanced by vapourizing some of the methanol because of increased heat, then an oposite reaction will take place to bring the mix back into balance. In this case, the opposite reaction will produce monos because the heat is in the range to set this process up. revese reaction can deminish yield and make washing more difficult. Tom

God sakes man Hooks right, keep your hand out of that damn bung hole!
Tom, I am interested in Jim's theory about back reaction though I would like some collaboration from other chemists with experience in biodiesel brewing. Perhaps Jim can give more of an explanation?

How can you demeth with temperatures below 55C (131F)?
My processor isn't sealed but rather vented through my collection carboy via my condenser. After processing for a 3 hour period at 150+ I will typically have around 250 to 500ml of methanol in the carboy. Not enough to worry about, I could just pour it back in I guess too...
I once got impatient and started to add the caustic at around 170F and the methanol seemed to be boiling out as fast as I could add it.
In my experience though if kept below 160F it processes fine.

There is no doubt in my mind that the boiling point goes down once mixed with the oil as I witness this effect every time I brew.

Jon

I see I was too slow and missed your post Tom.
Thanks for the explanation!
I would still like to hear another professional opinion to be convinced though.
Call me a sceptic...
Jon

Jon
-Jim is a member of this board.(narfien) he would much rather have discussions by e mail. so you can talk to him direct, you have his e mail address from the e mail I forward to you. as you have seen , he has lots of gooood info.
-I also added methanol on one batch when the wvo was at 170f, it blew the bung from the top of the processor. the bung is abs so the methanol fumes and heat keep it kind of soft so if too much pressure builds, it pops out. SAFETY Tom

Like I said I routinely process at 70C--

Neutral's experiments--

http://biodiesel.infopop.cc/ev...=295109316#295109316

show that there is no appreciable vaporization of the methanol from the mixture until 77C when some refluxing begins--

I have no readily apparent losses at 70C and haven't failed a 3/27 test in several years--

ReM

ReM
-I understand, your reflux coumn returns the condensed methanol to the reaction so that makes sense to me now. I'm still not sure about the hight temp in that situation. I'm waiting to see what the biodisel chemist has to add on this subject, I will post his answer here. Tom

quote:

Originally posted by Biotom:
ReM
-I understand, your reflux coumn returns the condensed methanol to the reaction so that makes sense to me now. I'm still not sure about the hight temp in that situation. I'm waiting to see what the biodisel chemist has to add on this subject, I will post his answer here. Tom

NO--

There is no need for a reflux column under about 77C--

ReM

Combining 2 soluable substance with different boiling points will change the boiling points of each substance. The boiling point of A will move in the direction of B, and the boiling point of B will move in the direction of A. You will not see the full expected theorectical shift due to A and B (oil and methanol) being only partially soluable in each other.

The other issue I see addressed here is mono-glyceride content at high temperature. I have ready multiple studies that show the equilibrium constants of the reaction and at higher temperature there is a slight shift toward reactants. However in my experience (processing as high as 200F) the shift has been so small that it has not affected our ASTM compliance.

quote:

Originally posted by Biotom:I removed the bung on top of the processor and put two fingers into the tank, it was dripping with methanol. Temp 65C or 150F

I agree, I get a significant amount of methanol condensing on the top of my processor when I process at 55 C. So much so that I want to insulate the flat, unsealed, top of my processor. Although this way not all of the methanol is escaping but rather it simply liquifies and drips back in.

At 55 C, I process for an hour and pass a 3/27 test if I did my math right. Saving 1/2 and hour or 45 minutes just isn't a big concern...

Helping hand
-thanks for the good info info! the fact that wvo is not fully disolvable in methanol was part of the reason for my concern, so the methanol boiling point is raised slightly, but even at 200f the reverse reaction does not affect the astm for mons, right? This is the practical part of the puzzle that I was looking for! As you know not all things in theory work the same way when put into action.
-could it be that the increased amount of methanol that we use helps to reduce the amount of reverse reaction, because the reaction is never realy starved for methanol even though some is vapourizing? The commercial producer I've been talking with only use 12% methanol, I use 20 - 22%. Seems that temp control would be more of a factor for him than us.
-I think the info you bring forth here would also apply to the thread about reverse reaction during WBD Tom

quote:

Originally posted by regger:I was wondering if anyone knew of a method to reduce Polymerization during the creating of Canola Biodiesel.

What are you seeing that makes you think that there is polymerization occurring during the processing of your BD. It was my understanding that polymerization appears as a sediment in the bottom of storage containers. I process at 55 C and then dry my washed BD at 110 C before storing in completely full jugs (no air space)and I have not seen any sediment or other indications of polymerization.

quote:

-could it be that the increased amount of methanol that we use helps to reduce the amount of reverse reaction, because the reaction is never realy starved for methanol even though some is vapourizing? The commercial producer I've been talking with only use 12% methanol, I use 20 - 22%. Seems that temp control would be more of a factor for him than us.

That makes good sense to me Tom, I use 22%.
Thanks for your input HH.
Jon

quote:

What are you seeing that makes you think that there is polymerization occurring during the processing of your BD. It was my understanding that polymerization appears as a sediment in the bottom of storage containers. I process at 55 C and then dry my washed BD at 110 C before storing in completely full jugs (no air space)and I have not seen any sediment or other indications of polymerization.

I have seen sediment when taking samples from the pump on our reactors, I cannot be 100% sure that is what is occuring but that is my best guess. I recently had reduced the temperature from 65 to 60 degrees C, and the results appeared to be much better. Especially as far as a 3rd bottom later occuring and the amount of Monoglycerides present