Earleir this week I had an experience like I've never heard about while recovering methanol from BD. Any chemists on here ...please explain?

I was recovering methanol from a batch that didn't seem unlike any other batch ...except I got distracted. My wife and I went out to dinner and I forgot about the BD cooking in the reactor. I have a temperature controller on the reactor that controls the temperature very closely. It was set to 180 F +/- 2 F. The batch cooked for several hours. When I returned from dinner (...um ...and a movie) with my lovely wife, I discovered the batch I forgot about cooking along. The carboy had quite a bit of methanol in it which seemed a little odd but the more noticeable aspect of the batch was it turned dark in color...almost back to the color of the original wvo. I had already removed the glycerin byproducts before starting the demeth operation. I opened the top of the reactor to discover a very syrupy dark batch. I dipped a stick in it and while it was hot it seemed very liquid but when I pulled the stick out it was coated with something ...I think the stick being cold solidified the cooked BD that touched it. Also, the stick was dripping long stringy drips. I held the stick way up in the air and the drip stretched all the way to the ground.

I don't know how well this description is being understood, but , if someone out there knows what the heck happened ...please let me in on it!

Is it possible to over cook BD? Can it "polymerize" somehow?

I poured the contents of the reactor into several carboys...by morning it solidified like the glycerine byproduct on a cold night but only this stuff was in a heated room (70 F or so) and it did not resemble biodiesel at all anymore.

I'm on vacation in Florida right now but when I return home I'll try to take some pictures. If anyone out there is interested in a sample to help the investigation, I would be willing to ship one just to have the answer to this puzzle. If there are an questions, please ask away or PM me with you phone number and I'll call you.

Thanks,

Rich Scorzelli

Rich,

Nice description. I had a similar experience.

I settled and removed the glycerol from a batch. Then, transfered the batch to a separate tank to remove, and recover, methanol. I figured I would be very accurate with the reaction so began periodic testing both "flash point" and "% methanol remaining". My plan was to remove the methanol to the point where the remaining soap and glycerol would no longer stay in solution, and to determine the flash point at that time.

Well, the reaction went on for a couple of days before I reached the point where the soap started to form into clumps.

Two things happened to this batch.

One: the BD failed an actual GC test for glycerides. It had previously passed a 3/27 test after settling. In fact the 3/27 went all the way to 15/27 with no haziness in the methanol and no drop out.

Two: I recovered more than the expected amount of methanol.

My theory is the long methanol removal time at elevated temperatures caused the reaction to reverse. As the soap and glycerol slowly came out of solution then the glycerol gave up its previously captured catalyst. This, in turn, provided the environment for a reverse reaction. The conversion of glycerol back to mono- di- and tri- glycerides also produces methanol as a by-product.

When I reprocessed the batch I started with darker than normal biodiesel that produced a lot of soap and glycerol. The soap and glycerol clumped together in long sinewy, semi-solid clumps. Much like you described.

I did not use a water pre-wash prior to settling the glycerol and soap from the biodiesel. I will do this with next batch.

rich can you tell me what it smells like?
what was the titration ?

what kind of oil was it?
I suspect what youve made here is a load of soap and fatty acids.
can you test the pH of the distilled methanol and of your mystery product
also do a titration on the mystery product.
but from what you say I dont think it has polymerised, answer the questions for me and do the tests and i'll see whats what

Hi Rich and Producer and Topaz,

This may be a load of rubbish, what I'm going to say, but it may be a clue to this.

Producer, can you tell me, did you put your hot biodiesel into a HDPE container at any time during the process when this happened to you?

I've got a sneaky feeling HDPE containers MAY trigger a rapid polymeric reaction if they have hot BD in them.

Reason I say this, I made a batch some months back, and stored some in steel drums, some in HDPE. I poured the BD into the drums while pretty hot, I guess 75C or more. Then they sat in the sun for a week or 2. The HDPE drums were dark blue.

The stuff in the steel drums was normal, some weeks later.

The stuff in the HDPE smelled really strongly of paint / varnish. It was an acrid smell, very harsh on the throat.

I just get a sneaky feeling that very hot HDPE may offer a trigger mechanism for polymerisation.

Rich I believe you use HDPE, so this is what triggered the thought of this possibly being the common link.

Of course, it could just be that UV may be able to penetrate the HDPE drums - dunno. If so, Rich, during this process, was your processor out in direct sunlight?

Anyone else ever noticed this?

graham, tell me the metal drums and the hdpe were they both air tight and if so did you notice the hdpe drums sag from the reduced air pressure inside

as a slight meander Graham, what mileage do you get from your Fabia?
cheers

All,
I will return from Florida on 26 Nov and provide answers to questions. ...and, Graham, I am using HDPE cone-bottoms.

Graham, sorry for the slow response. I was traveling over the holidays and only made a couple of cursory checks of the web site.

quote:

Originally posted by GrahamLaming:
Hi Rich and Producer and Topaz, . . .
Producer, can you tell me, did you put your hot biodiesel into a HDPE container at any time during the process when this happened to you?

Quite the opposite, I have absolutely no plastic in the system except the site tubes. These are closed at all times except when checking fluid levels.

My tanks, piping, and pumps are all carbon steel.

Just thought I'd add my comments, although I don't think it is quite the same as Rich & producers situation.

Last weekend I allowed my methanol recovery to run for a long time at 75-80 deg C. At one point when I checked, there was foam being drawn up my vapour return line and brown liquid in with the recovered methanol in the carboy. Pump agitation continued for the entire time. My thought is that once all the methanol was removed, the soap in the biodiesel formed a foam in the head space of my WH reactor and then was drawn though the condenser by the venturi. I can't think of any other explanation.

The biodiesel looks ok, will have to see once it has finished settling.

Has anyone had soaps clog their processor before they pump out the biodiesel? At what temperature is this likely to happen, or could it happen as soon as the methanol is removed?

nzu..,

I have that happen to me quite often ...the soap foaming up on top of the BD during meth recovery. I usually us a macaroni strainer and scoop out the floaty stuff before I drain the BD into my settling tank.

Topaz...I still haven't checked the pH of my recovered meth...sometime tonight...but the BD "mystery product" that is the subject of this thread is solid at normal room temp. I am not sure how I can titrate that. The oil that I started with was two carboys of peanut oil and one carboy of that "creamy" Zero Trans stuff.

Rich

My processor is a sealed hot water cylinder so there's no way to scoop anything off before draining to my settling tank.

Do you think the foam starts to form part way through your distillation or only when the majority of the methanol is driven off?

nzu..

I can see thru my processor as it is HDPE plastic. The foam starts when about half of the methanol is gone. I am using Graham Laming method with venturi to aerate the BD and then it splashes down on the surface of the batch so if soap is present, I don't see any way around avoiding some foaming. The foam gets pretty tough sometimes...maybe because there is some glycerol byproduct present and gets entrained in the suds. If I didn't skim it off the top, I am certain it would plug up the bottom drain.

I am actually thinking of going to water washing and then using the venturi drying method to remove the water quicker. There is not much mathanol in the batch anyway...2%-3% by volume. The real bang for methanol recovery is in the byproduct.

I understand the issue with methanol escaping into the air and I will minimize that by keeping the system as closed as possible...the wash water will just go into the septic system and feed the bacteria there.

My suspicion is that there is some amount of reverse reaction going on because I can't seem to consistently pass the 27/3 test after demething. Of course this remains to be proven because I need to do the 27/3 test before demething and then again after demething and compare results.

Cool stuff!

Topaz,

The pH of the recovered methanol is between 7.0 and 7.3. I'll try to check purity by specific gravity. Seems like there might be quite a bit of water in it.

Just measured off 1 liter of recovered methanol from my mystery batch and it weighs 811 grams. So there is some water in it...maybe not as much as I suspected. ...approx 90% methanol...10% water. ...not sure if this is a lot of water or not ...anyone with experience have any input?

Hi Rich,

Are you doing the 5% pre-wash. I am and usually get about 93% purity when I demeth. I usually also pass 3/27 both before and after, I try to be very careful about draining all of the glycerin out before demething.

Tony

I am doing the 5% prewash.

I just wanted to be clear about the 27/3 test. I am getting a very light wispy precipitate that settles to the bottom very slowly...overnight. I am not getting any amber colored oil droplets in the test. I am told that it is an "almost passed" result. I am really wondering if we truly know what the white precipitate is. It does not look like unreacted oil at all. Could it be soap/water or possibly waxes that will never be reacted? I guess I'll have to break down at some point and get a GC done on the precipitate. I am seriously thinking of spending the $7K-$9K for my own personal GC...because one question just leads to another and one test hardly seems like enough information.

I wonder if we have enough interest from people in this forum to group purchase a GC to be used by any one of the "charter group" purchasers free of charge as often as they want. Any interest?

quote:

Originally posted by RichScorze:
I just wanted to be clear about the 27/3 test. I am getting a very light wispy precipitate that settles to the bottom very slowly...overnight. I am not getting any amber colored oil droplets in the test. I am told that it is an "almost passed" result. I am really wondering if we truly know what the white precipitate is. It does not look like unreacted oil at all. Could it be soap/water or possibly waxes that will never be reacted? I guess I'll have to break down at some point and get a GC done on the precipitate. I am seriously thinking of spending the $7K-$9K for my own personal GC...because one question just leads to another and one test hardly seems like enough information.

I wonder if we have enough interest from people in this forum to group purchase a GC to be used by any one of the "charter group" purchasers free of charge as often as they want. Any interest?

The wispy stuff could be monoglycerides. When I've seen that, that's what it's been, as confirmed by GC and to a lesser extent pHlip testing.

quote:

Originally posted by GrahamLaming:
The stuff in the HDPE smelled really strongly of paint / varnish. It was an acrid smell, very harsh on the throat.

I just get a sneaky feeling that very hot HDPE may offer a trigger mechanism for polymerisation.

Hi Graham

HDPE is oxygen permeable and the acrid smell is from carboxylic acids formed from the breakdown of the BD.

Nick