Biodiesel and SVO Forums Home
Maybe reversed reaction?

This topic can be found at:
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/719605551/m/3437086183

January 19, 2018, 10:44 AM
Johann Cape Town
Maybe reversed reaction?
Has anyone experienced this?

400L UVO 80L methanol and 12g/l KOH (titration 3) So far pretty much the same for many years, process followed by whole batch demeth about 30L methanol recovered Yield without decanting glycerol was about 420L (estimated).

I process well in advance of need so let it settle for 2 weeks and drain glycerol and send the biodiesel to my storage / pump drums.

Here's the problem. After two weeks I set up to drain the glycerol but to my surprise there wasn't any. You know what it's like when you've drained bio and glycerol for years you can tell them apart by looking at the fluid stream. This behaved like bio. So I put a sample in a jar and it was crystal clear although a bit darker than expected. Zero separation. It looks like I have reversed the reaction by reclaiming too much methanol. If this is what has happened I've must have missed reversing by a small margin everytime I made the last 60 batches or so.

Anyway the product is clear and the viscosity is definitely little higher than biodiesel but nothing like UVO. I decided to see how it would perform in one of my VW 1.9 TDI's. I added enough to result in a 50/50 blend with decent bio already in the tank. So far after 100km's it seems fine. It's summer here and pretty hot so no cold weather problems.

I'll do some re processing tomorrow to see what happens but I must admit I'm tempted to run this as is.
January 19, 2018, 02:09 PM
Paulus
Are you sure you got a complete reaction in the first instance?
January 22, 2018, 06:49 AM
Johann Cape Town
Reaction was complete before WBD was started. Afterwards I took a room temperature 1L sample and added 100ml methanol only, shook it up and separation commenced immediately. So it seems one can backtrack if too much methanol is recovered.
January 22, 2018, 11:33 AM
Dgs
Johann, when you say your reaction was complete how do you know? did you conduct a 3/27 or better still a 10/90 or 30/270 if so how does the comparison of before and after tests compare.

If what you have now is more like the viscosity of bio you must have at least some reaction.

If you really have reversed the reaction (which I personally doubt) then surely over 60 batches it would have shown before now.
January 22, 2018, 11:51 AM
Johann Cape Town
Dgs 27/3 before WBD was almost clear. I should be able to recover 40L but normally stop at 30L as the energy/time required for anymore than that is significant (only 2000 watts for 400L).

I may have exceeded 40L recovered unknowingly as ambient temperatures were around 35C (95F) and evaporation may have played a part. I condense in a fan cooled radiator.

Anyway it appears the process can be pushed forward again by adding methanol only. I'm testing 1L batches and adding 10ml methanol increments to see when/if I pass 27/3 again.
January 22, 2018, 12:21 PM
Paulus
Im a bit rusty, but sounds like an incomplete reaction to me.
January 22, 2018, 04:34 PM
Dgs
quote:
Originally posted by Johann Cape Town:

Anyway it appears the process can be pushed forward again by adding methanol only. I'm testing 1L batches and adding 10ml methanol increments to see when/if I pass 27/3 again.


Hi Johann, that won't be possible without catalyst.

You know the 3/27 test is a very rough gauge, simply because you are only using 3mls of sample. However if you did a 3/27 on your de-methed product you would probably find the same result as your original (non de-methed) sample, proving the reaction had not reversed.

I have personally never come across reaction reversal after well over 250 batches of bio.
January 23, 2018, 12:27 AM
Tilly
Hi Dgs,

quote:
Originally posted by Dgs:
Hi Johann, that won't be possible without catalyst.
Are you sure?
I recall that just the other day , on a different forum, you were telling people you had a procedure where you were achieving up to 20% conversion before performing your first reaction!!! Wink






January 23, 2018, 02:43 AM
Johann Cape Town
Well yesterday I added 10ml of methanol only to 1L of the product, gave it a Tilly shake at room temperature and this morning I have clear separation. The "product" befor adding methanol showed no sign of separation after 7 days. Still poncing about in my dressing gown so will test later.

The limitations of 27/3 don't really concern me but I use it as a broad indicator. I don't sell biodiesel to others and carry the risk of bad fuel in my own vehicles which are pretty tolerant being two IDI motors, two 1.9 TDI's, and a PD motor. No bio related repairs since 2002. Also JFI we cannot water wash as we are drought restricted to 50L per person per day and facing taps off in a few months if we don't get decent rain.
January 23, 2018, 07:22 PM
Tilly
Hi Cape Town,

quote:
Originally posted by Johann Cape Town:
Well yesterday I added 10ml of methanol only to 1L of the product, gave it a Tilly shake at room temperature and this morning I have clear separation.
Oh well, if you gave it a Tilly shake there is no wonder that you have clear separation.
Everyone gets great results using the Tilly shake.






May 28, 2018, 03:59 AM
bbarclays
Just throwing my penny..
I have done reaction with propanol, KOH and Fresh veg oil at lab long time ago, there were no separation for months.Liquid was gold, clear altough density was higher than biodiesel, probably due to dissolved glyceryne phase.
May 28, 2018, 12:13 PM
WesleyB
There is 2-propanol (isopropanol) and 1-propanol (n-propanol). It makes a big difference in the base transesterification reaction. With isopropanol there is little or no reaction , with n-propanol it reacts the same as methanol if the alcohols are mostly anhydrous (without water).