Adding more Methanol post reaction?

[Dave Member Find all posts View Profile Close Dave]

I read this somewhere.

"After the reaction has finished, to settle in the reaction tank for one hour. After this time, there will be 5% of oil that has stil not been reacted. Add 1 more litre of methanol and continue reaction. Then, stop reaction with water"

What are your thoughts on this?

[reg Junior Member Find all posts View Profile Close reg]

Re: Adding more Methanol post reaction?

Depending on the size of the batch, is it really worth trying to get every last bit to react, let alone the extra work involved, plus i do not think methanol alone does anything apart from evaporating, this is why we have to make the methoxide.
Just a thought.

[joe Moderator Find all posts View Profile Close joe]

Re: Adding more Methanol post reaction?

Why bother wasting any amount more of methanol when some users use 100% oil. Doesn't sound entirely right unless it was methoxide that you where mixing back through. Better off remixing the glycerine back through. Its got methoxide still left in it.


Joe

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Adding more Methanol post reaction?

If the correct proportions of Caustic and methanol are used, then it will not make any difference to the conversion, but may cause some more of the soaps in the byproduct to be dissolved in the additional methanol.
If you are using an excess of methanol in the reaction (20% of vol of oil), there will be unused methanol in the byproduct and in the biodiesel.

I see no good reason to add more unused methanol.

Are you planning to recover the methanol?
Where did you get this snippet from?

I would be happy to hear or read the explanation for adding more methanol.

[Terry Syd Senior Member Find all posts View Profile Close Terry Syd]

Re: Adding more Methanol post reaction?

This sounds like some other misinformation like the discredited "Foolproof method". You can only get a further reaction from the addition of methoxide, not methanol.

Sometimes a person will take their finished biodiesel and then add more methoxide to see how much more glycerin they can settle out. This is can be used as a test to see how good the first conversion was.

[joe Moderator Find all posts View Profile Close joe]

Re: Adding more Methanol post reaction?

This sounds like some other misinformation like the discredited "Foolproof method". You can only get a further reaction from the addition of methoxide, not methanol.

Sometimes a person will take their finished biodiesel and then add more methoxide to see how much more glycerin they can settle out. This is can be used as a test to see how good the first conversion was.

I had great success from doing this before. Its surprising how much more will be reacted.
Joe

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Adding more Methanol post reaction?

Hello Joe,
Can you describe what you did and the results.

Tilly

[joe Moderator Find all posts View Profile Close joe]

Re: Adding more Methanol post reaction?

Hello Joe,
Can you describe what you did and the results.

Tilly

Its not very scientific but for a 20 litre batch I'll use a quarter of what I used for the first reaction. So approx 1 litre of methanol and about 40 - 60 grams of KOH depending how much I used in the first reaction. I would get good seperation and 1 litre of glycerine.

Dunno if it means that I should have used more in the first reaction however but I do the titration accurately and often more than once. However I find I can still get more out of it with the second reaction. I used to do the same with beer.

Joe

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Adding more Methanol post reaction?

Joe,
Are you adding 3.5g + titration amount per litre in the main reaction,
or 5g + titration per litre of oil?