Testing the Two Stage Base/Base method

While the 2 stage Base/Base method is being recommended more and more as a procedure to use, I can find no test results posted on the internet to support its use.

I Had my good friend Mickey perform a small test a while back that showed that with lightly used WVO it was possible to reduce the amount of NaOH used by about 1g NaOH per litre of WVO reacted and still achieve the same results as the single stage method.

It was suggested to me that a test should be done with high titration oil.
I contacted me good Mate Mickey and had him perform a few tests.
We decided that the first test series should be aimed at determining whether the single stage method could produce Very high conversion biodiesel when reacting high Titration WVO.

This is the series as Mickey teletyped it to me

FIRST TEST SERIES
*WVO used- Palm oil titration 10 with 90% KOH (This is the highest titration oil Mickey has)
*KOH- 90% purity
*Viscosity testing as per the World Famous Dr Pepper *Viscosimeter(Pat Pend)
*All viscosity tests performed at 21deg C.
*Calibration of Viscosimeter- 1% unreacted oil increased run time by about 0.4 seconds



Test A
1 litre above WVO
250ml methanol
22g KOH
This was supposed to be as per Neutral’s recommendation for very high conversion biodiesel, using 10g KOH as b the base amount. KOH= b+(tx1.2)= g KOH
Unfortunately, I forgot to factor in the 90% purity for the base amount and came up 1g KOH short in this reaction, it should have been 23g KOH
Viscosity run time average
1 min 7.81sec
passed Warnqvest conversion test

Test B
Same as test A except increasing KOH amount to 27g KOH
Interestingly, this batch only had a 1cm layer of biodiesel on top with no noticeable separation I continued to shake it for the required time and added 80ml water at the end for an 8% water wash.
Seperation then occurred and washing proceded as normal.
Viscosity run time average
1min 7.74 sec
Passed Warnqvest Conversion test

Test C
Increased Methanol to 300ml and KOH to 30g.
This batch showed no signs of separation.
After the required reaction time the 8% wash initiated separation and washing was uneventful.
Viscosity run Time
1min 7.72 sec
Passed Warnqvest Conversion test

Test D
Reprocessed biodiesel from test B- 1.4g KOH mixed into 50ml methanol per litre biodiesel reacted.
No separation occurred.
Washed normally
Viscosity run times average
1min 7.73sec

Conclusion
Batch A,B,C and D were of virtually identical conversion.
The Reprocess showed no increase in conversion.
It is possible to make very high conversion biodiesel from high titration WVO using the single stage method

More tests to come

Second Test Series

This series was designed as a “Head to Head” comparison of the single stage and 2 stage Base/Base method with high titration WVO.
WVO was from the same batch as above, Palm oil titrating at 10 on the KOH scale.
KOH was 90% purity
Viscosity testing was as above.

Batch E
This batch was as per Neutral’s suggestions for “Just Scraping in” to ASTM conversion
220ml methanol
KOH amount= b+(tx1.2)
b= Base amount of 7.8g KOH
Total KOH used- 19.8g KOH.
Viscosity run time average
1min 8.75sec
Failed Warnqvest Conversion test But not by much

Batch F
This was a straight 80/20 base/base procedure. Using the formula 7.8g KOH+ titration
Methanol in the first stage175ml and KOH for the first stage 14.3g. Methanol in the second stage 45ml and KOH for the second stage 3.5g
This gave a total of 220ml methanol and 17.8g KOH for the entire reaction.
Results: The first stage did not separate
I was amazed, It never occurred to me that the first stage would not separate.
Added additional 25ml methanol and still no separation.
Added additional 3.5g KOH in another 20ml methanol and achieved separation

Batch G
After the surprise results in batch F I decided to do an 80/20methanol 90/10 KOH Base/Base batch.
First stage contained 175ml methanol 16g KOH.
Results: No Seperation in the first stage

Conclusion
Neutral’s recipe for “Just Scraping in” for ASTM conversion does not “scrape in” for high titration WVO.
A lot more testing needs to be done with the 2 stage base/base method and high titration WVO.

Thanks Tilly. Interesting.

Hi Tilly-
Your post is timely. I just made two 150 l batches in side by side water heaters - one being the single stage the other base/base. If there was a difference in the final amount of product (both of which passed pHlip) I didn't see it. I triple checked all my numbers going in, but figured maybe I did something wrong. Perhaps it wasn't wrong. Thanks.

Hi Tilly,

Thank you for posting your test results. They are very informative.

2-stage base base works for us far better than 1-stage base, when we are working with high-FFA feedstocks that have not been 100% dewatered. With 1-stage, we had batches that needed re-processing. That has never happened with two-stage.

We are working on getting better dewatering of oil, and then maybe it'll conceivably be a tossup, but still, there seems to be no reason to favor 1-stage over 2-stage, if you have the time and resources. From a chemisty perspective, the 2-stage simply makes sense, and it works.

Curious what Girl Mark has to say about this.

Hello kumar

What formula do you use for the base/base method and the single stage method?
Can you explain what you mean when you said:
"From a chemisty perspective, the 2-stage simply makes sense, and it works."

I am really keen to see any "Head to Head" comparitive testing that has been performed that compares the Base/Base method to the Single Stage Method

I assume since the debate is about high ffa oil, if you've got low ffa oil there is no point in going to the trouble of the second step?

Hello csp97

I have never seen any test results or performed any tests that suggests the 2 stage Base/Base method can produce higher conversion biodiesel than the single stage method in any situation.
As far as I can tell, If your reactor is of sound design and you use the correct amount of chemicals, There is never any reason for going to the trouble of the second step no matter what the FFA content.
I would turn Kumer's above statement around a little bit and say "there seems to be no reason to favor 2-stage over 1-stage"

I have repeadedly asked for the people who recommend the 2 stage Base/Base method to post test results that support this recommendation. So far no one has.

I make fuel every week from 12 or higher wvo, it is routine for me, my fuel always passes the warnquist test, and runs great in my vehicles.

Hello fabricator

What method do you use, 1 stage or 2 stage Base/Bse, or Acid/BAse?
Do you use KOH or NaOH?
Have you ever performed any "Head to Head" tests with the 2 stage Base/Base and the single stage method.

quote:

I have never seen any test results or performed any tests that suggests the 2 stage Base/Base method can produce higher conversion biodiesel than the single stage method in any situation.
As far as I can tell, If your reactor is of sound design and you use the correct amount of chemicals, There is never any reason for going to the trouble of the second step no matter what the FFA content.

Tilly, I'm finding from my conversations with homebrewers across the US that the SINGLE most important factor in determining if someone makes high quality biodiesel is quality testing. Without quality testing providing the feedback that is then used to adjust the recipe and process, there is little or no hope for making ASTM spec fuel.

You have been a pioneer in quality testing and have helped Mickey and friends for years to make high quality fuel. The warnquist test is the best quality test youv'e come up with yet! It's so much simpler than viscoscity testing or reprocess testing that people are actually using it to improve their fuel.

I've also found that when armed with a good quality test like the warnquist test or the pHLip test homebrewers can make just about any technique or method work.

Not to speak for any advocate of the two stage base/base process but myself, when flying blind without a quality test for feedback, the two stage base/base method works with the standard recipe, and it works with NaOH on higher titrating oils. There is some advantage in that for some people.

I have talked to a number of good people that have made ASTM spec biodiesel using both the two stage base/base method and the single stage base method. The common thread is that both work, but you have to really add a lot of catalyst over the standard recipe to get the single stage method to work on higher titration oils. Also the higher titration oils are best worked with KOH, like you did, since NaOH tends to produce glop at the levels of catalyst needed.

I want to thank you again for introducing the warnquist test to us. It has given homebrewers the tool they needed to break out of the box and try new methods of making biodiesel.

I have done head to head tests on 1 VS 2 stage and gotten better results with 2 stages, in my appleseed and in my friend's. Without changing recipe, oil input, temp. etc., 2 stage passes 3/27 and 1 stage does not. I am working to improve my equip., and hope to continue producing a quality product with less methanol. We will see if it works. So far, I see no reason to use 1 stage when 2 stage is only a bit more work with clearly better results for me. Andrew

PS. I am suspect of any assumption that what happens in 1 l bottle will be the same as what happens in the reactor. Few if any processes are exacly the same at different scales. Could be 2 stage compensates for less effective mixing?

Hello Andrew,
You said:
"Could be 2 stage compensates for less effective mixing?"

I think this is a distinct likelyhood!
As you may have noticed, I continually say:
"If your reactor is of sound design and you use the correct amount of chemicals,..."

quote:

Originally posted by Tilly:
Hello fabricator

What method do you use, 1 stage or 2 stage Base/Bse, or Acid/BAse?
Do you use KOH or NaOH?
Have you ever performed any "Head to Head" tests with the 2 stage Base/Base and the single stage method.

I have never felt a need to use anything but the single stage method with KOH

The first two batches of BD I made were single stage using the standard KOH recipie. I was concerned with the results because the 1gNaOH + 50mL methanol test always dropped some glycerine.

Then, I read about the 2-stage base/base. I tried it (std recipie), and the product easily passed the 1g+50mL test! Although it is not an accepted indication of quality, the color of the product was significantly lighter, too.

Since then, I always use the 2-stage base/base. I prefer this over using more meth and KOH to force 100% in a single stage. (Sometimes I do two stages in one evening, and sometimes I do the 2nd stage 24hrs later. If I wait, I have to reheat. There is no noticable difference in the product.)

Soon, I would like to try acid/base to see if that improves the yield on this 6.5 titrating oil.

Specs:
WVO titrating 6 - 7.5, filtered 10-micron & vacuum dried;
20% meth;
titr + 7.5g KOH;
2-stage: 80%/20% meth 90%/10% KOH;
85 - 87% yield after wash+dry;
143F reaction temp, ~5psi pressured reactor