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Homebrew Acid-Base Biodiesel Recipes
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quote:

The purpose is to increase yield of BD and reduce soap right?


Right.

quote:

If I convert the FFA to BD by adding acid...and now have to add more KOH to neutralize, don't I create salt water which will now create a lot more soap?


First, it's the methanol that makes BD from FFA, of course. The sulfuric acid is just a catalyst. You do need to add additional KOH to neutralize the sulfuric acid, and that does produce potassium sulfate (plus a little water), but soap has nothing to do with potassium sulfate or salt. The K2SO4 goes into solution in the glycerine phase and has no important effect on the process.
 
Location: Sierra foothills | Registered: December 20, 2000Reply With QuoteReport This Post
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I'm trying the acid/base for the first time on a batch of 500gal. The oil titrated at about a 6. I used approx. 2ml H2SO4/liter of oil (approx. 0.8 gal for the 500 gallon batch). After 30 hours of mixing at 120-130deg F I titrated it at about a 4-4.5. I decided to go ahead and do the base step. However at this point it took me an equivalent of 12.5g KOH/lit oil in the lab to get this to actual break into bio and glycerin. Does this sound accurate? It seems like a lot of KOH to get the reaction to take place. Any help/advice would be greatly greatly appreciated. Thanks.


Dave McCandlish
President, Ohio Agrifuel
B.S., ChE Ohio University
 
Registered: May 09, 2006Reply With QuoteReport This Post
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OU_Dave,
-Ouch, no small test batches in the lab before doing the 500 gal batch? I'm nervous about trying it for the first time on a 55 gal batch in my garage...

Y'all,
-Thanks for all the great info, I look forward to trying this method.
Supply question: One economical source of H2SO4 (Sulfuric Acid) I found is my local auto parts store. They sell battery acid in 5 gal quantities for under $20. I find this desirable. Unfortunately, I am not sure about the concentration. I got a copy of the MSDS hoping to find specific info on purity, but all it says is: COMPOSITION - Sulfuric Acid >51%, Water - remaining balance.
So...
1. If i assume that the battery acid is only 51% Sulfuric Acid by weight, and if I use it, will the addition of that balance of water to the Acid catalist stage inhibit effective reaction?
2. Is there an economical source of more pure H2SO4 that some of you can recommend? (In the central California, Bakersfield region)

BTW, my oil titrates at 13.5 KOH.

-Carnie, Wannabe Homebrewer
 
Registered: May 07, 2008Reply With QuoteReport This Post
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Carnie,
I did a test batch in the lab, but unfortunately, as most of us know, just because it works on a small scale doesn't mean that it will work on a 500 gallon scale! I've figured out what happened anyhow. The FFA was low enough that the acid/water mix stayed on top, not the bottom like I had anticipated. So, as a result, I neutralized what acid was still there moreso than convert oil.

-Dave


Dave McCandlish
President, Ohio Agrifuel
B.S., ChE Ohio University
 
Registered: May 09, 2006Reply With QuoteReport This Post
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quote:
1. If i assume that the battery acid is only 51% Sulfuric Acid by weight, and if I use it, will the addition of that balance of water to the Acid catalyst stage inhibit effective reaction?

2. Is there an economical source of more pure H2SO4 that some of you can recommend? (In the central California, Bakersfield region)


Yes, battery acid is too weak. Try a Google search for "laboratory supplies" or "chemicals" followed by the city of your choice. Fresno might have some, I haven't found any yet in Modesto. You may have to go to Sac or LA.
 
Location: Sierra foothills | Registered: December 20, 2000Reply With QuoteReport This Post
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OU_Dave,

you use too much acid...
if your starting titration was 6 then you should have use (6-3)*0.2 = 0.6 mls per liter of acid not 2..or almost 4 times too much acid.

at 6 this is below my lower limit of 7 before I start to think about using an acid stage.

I appalled you for jumping in at trying a 500 gallon batch..Smile

also below 14 KOH don't worry about draining. there's not enough water created to effect yield more than 1-2%.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post



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I agree with the other battery acid is too weak..

water is the killer of acid processing and using acid that 49% water??? might work at low levels, say 5-8KOH, but above that..I don't think so..

try looking at drain cleaners..the acid kind they are usually over 90%..

just my 2 cents

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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Just a bit of information if you can not find the concentration/purity of the acid just ask to see the MSDS sheet on the product it will have the % of active/inactive ingredients.


quote:
Originally posted by Murphy: In short, this place is like a multi-dimensional bull$hit detector on steroids
 
Location: In the Pacific Somewhere | Registered: January 25, 2008Reply With QuoteReport This Post
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quote:
Originally posted by dkenny:
OU_Dave,

you use too much acid...
if your starting titration was 6 then you should have use (6-3)*0.2 = 0.6 mls per liter of acid not 2..or almost 4 times too much acid.

at 6 this is below my lower limit of 7 before I start to think about using an acid stage.

I appalled you for jumping in at trying a 500 gallon batch..Smile
-dkenny

Thanks
quote:
Originally posted by dkenny:
also below 14 KOH don't worry about draining. there's not enough water created to effect yield more than 1-2%.
-dkenny

How do you deal with the salts made when the KOH neutralizes the H2SO4? I've found them to be a real pain. The seem to interfere with the separation when I've tried it. Suggestions?


Dave McCandlish
President, Ohio Agrifuel
B.S., ChE Ohio University
 
Registered: May 09, 2006Reply With QuoteReport This Post
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I don't worry about them. they end up the glycerin which gets drained out. you might try a 5% prewash after the final base stage. otherwise I haven't had any problems with settling.

trying to do a 27/3 after the base stage the settling does seems to take longer but not much longer.

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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The problem is that mine goes through an Alfa Laval centrifuge, and the salts get packed on the inside. It's a real mess to clean up. That's why I was wondering if there was another way. I've heard that mixing in glycerin cocktail from a straight base process does a good job of getting the water/acid/methanol out, which settles it faster as well.

-Dave


Dave McCandlish
President, Ohio Agrifuel
B.S., ChE Ohio University
 
Registered: May 09, 2006Reply With QuoteReport This Post
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dkenny,
I would like to try this as you have outlined and want to see if I am understanding the process correctly. If I had oil that titrated at 9 it would be as follows?

Starting titration 9
- desired ending titration 3
=6

desired reduction FFA 6
formula for H2SO4 x.2
=1.2

my oil batch size 132.5L
ml H2SO4 per L oil x1.2
total amount H2SO4 =159ml

If the numbers are right then I would heat the oil and add the 159ml H2SO4 to 17.5L(60%) of methanol and mix for 12 to 24 hours. Drain nothing, then continue with the base stage after re-titrating to establish the correct mixture of catalyst dissolving the appropriate amount of KOH into the remaining 11.6L(40%) of methanol and finish processing as I have for my single stage batches.
Am I correct in assuming the advantages of this are a higher yeild and less KOH consumed? I also wonder if the glycerol is a bit more difficult to clean up for disposal and are there any effects on methanol recovery from this. I would assume that this will work with the G/L Eco-system which I am getting ready to add to my processor. Am I missing anything?


Regards, Mike

Biodiesel disposal units:
1999 Dodge Ram 3500
John Deere 455 tractor
 
Registered: August 31, 2005Reply With QuoteReport This Post



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how come it looks like to me that you use 2 different amounts of acid depending if you titrate with koh or naoh my titration is 11.5 with koh and 8.0 with naoh that is 1.7 ml h2so4 with koh and 1.0 ml h2so4 with naoh why the big difference to achieve the same goal? or am i doing something wrong I titrated 4 times with each solution the outcome was consistent should the titration results be similar between koh and naoh? did i have something wrong with one of my titration processes? thanks for your replies marvingvx
 
Registered: August 30, 2008Reply With QuoteReport This Post
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Viva el fatta!!!

For the third time, (first two were unsuccessfull) i tried the fatta method with one of my two wvo supplier... Success !!! I was able to bring an oil that titrated at 6.6 down to 1.33, yes 1.33 (i'm titrating with 30 ml of isopropyl and 3 ml of oil, hence the precision level)(titrated with NAOH)

I understood a couple of things this time:

Too little methanol and the reaction will take forever to take place.
Too much acid and even if the FFA are converted, you'll end up with a high titration number anyway, and the quantity of NAOH will be too much.(i tried)
It's amazing how much methanol you lose if your reactor is vented, i sealed the reactor as soon as the methanol/acid was in.
After the first hour, titration level was 4, after 2 hours, titration was 2.66... after 9 hours of reaction, i finally got 1.33, witch is way beyond my nastiest dreams.

Here is what started with:

65 liters of oil (6.6 NAOH) heated to 140 deg. F.
I wanted to attain a titration level of 2.5 so: 6.6-2.5=4.1, 4.1x.2=.82ml of acid per liter of oil. So .82x65liters=53,3 ml of acid
But i have 66 Beaume H2SO4 (93%) then 53,3 divided by 0.93=57.3 ml of acid.

In how much methanol ? 2/3 of 25% of 65 liters=10.725 liters of methanol.
So, i put the methanol in a carboy, and then put the acid in the carboy with the methanol, shake the whole thing up for a few seconds.
Then, put the acid soup in the reactor... sealed the reactor and started the mixing pump.
I took the titrating oil via a sampling valve but never relieved the pressure from the reactor.
Now, the base stage: Put 80% of 1/3 of 65 liters = 4.3 liters of methanol with 390 grams of NAOH, Relieved the pressure in the reactor , shaked the carboy till dilution, and put it in the reactor, re-sealed the unit.

I'm keeping the last liter of methanol for the 20 part of the 80/20 base/base method.

I will post tomorrow with the yield obtained that way...
 
Location: canada | Registered: October 03, 2008Reply With QuoteReport This Post
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Viva el FATTA...

Yields are 63 liters bio over 65 liters of starting oil: 97%
I am now trying 5% water prewash...

Bruno.
 
Location: canada | Registered: October 03, 2008Reply With QuoteReport This Post
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What is your base naoh value for your 80/20 or do you use just titration values?
 
Location: Norse | Registered: March 22, 2007Reply With QuoteReport This Post
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Holy crap, where are some of you guys getting these bizarre recipes?
 
Location: West Michigan | Registered: April 26, 2006Reply With QuoteReport This Post
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Well, i just used the total Naoh amount for the titration and used 80% methanol, i did not use the last liter of methanol since the bio passed the 27/2 test right away.

I guess that 25% methanol was a little too much since when i checked the glycerine content before water wash, it was quite liquid.

Fabricator, these strange recipes are for yield purposes and for the easiest wash possible because i suspect my oil is moist and i can't stop clogging my magnesol filters with soap in suspension in the bio.

By the way, anyone have a good method of filtration for the magnesol that does not need constant attention at hte filtering stage ?

Regards.

PS, just to add sone snake oil, when i do a straight transesterification on a high ffa oil, i do a sulfonation of the bybroduct with sulfuric acid, in the first seconds, the catalyst and glycerol precipitate at the bottom leaving a solution of ffa and methanol on the top. depending on the ffa and methanol content, i am able to squeeze out 75% of ffa soup witch i mix 50/50 with heating oil and burn it in an oil stove... JTF told at least one truth: ffa burns quite well...

So, in a 160 liters batch, i can get as low as 10 liters of waste...(But what an unusable waste !!!)

Have a nice day you all...
 
Location: canada | Registered: October 03, 2008Reply With QuoteReport This Post



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We have been doing a form of the FATTA method for about 2 years now on 275 gallon batches.

I believe that perhaps the acid quantities might be a bit high using the starting titration - ending titration * 0.2 formula. I base this on my own experience adding only 1ml/L 93% H2SO4 no matter what the initial titration is.

We add our acid to the oil first and then 14% by volume of methanol is inducted.

In the past we followed with acid esterification with a single stage base but had intermittent problems passing 3/27 tests for reaction completion with ending titrations between 1.4ml-2.6ml 0.1N NaOH.

For the last 20 batches or so we have been doing a 2 stage base; 70/30 to 80/20 with anhydrous sodium methylate.

We process mainly chicken fat with 10-20% assorted waste vegetable oil, the combination normally titrates between 6ml-9ml 0.1N NaOH.

Using the formula would dictate 0.92ml/L or 1.38ml/L which is actually pretty close to what I use.

There are couple of observations I have made over time that don't seem to have been mentioned before.

People have asked about neutralizing the acid, reference to 2.9g/L NaOH to neutralize a titration of 2.6ml NaOH. It has also been mentioned that the titration accounts for this neutralization and you don't need to bother adding any additional catalyst outside the calculated formula.

This is all true. However;

Neutralizing sulfuric acid requires 2 mols of NaOH for every 1 mol of H2SO4.

NaOH weighs ~40g/mol, while H2SO4 weighs ~98g/mol. So really you need 80g NaOH to neutralize 98g H2SO4.

Since our chemicals are not pure we need to accommodate these impurities.

NaOH 80g/95% = 84.0g
H2SO4 98g/93% = 105.4g

So 84g of 95% NaOH will neutralize 105.4g of 93% H2SO4.

What about water? Besides creating water during acid esterification we also create water when we neutralize the acid. For every mol of acid you neutralize you create two mols of water.

So if you were to use 1L 93% H2SO4 you would have 1711g of H2SO4 or 17.46mol. This means that you get 34.92 mols of water. Water weighs ~18g/mol so we have only created 628.56g of water in addition to the 70g of water present in the initial volume of 93% pure acid.

In total we end up with 698.56 grams of water or about 0.7 litres.

So the neutralization doesn't really create that much water. However the more acid you add, the more you eventually neutralize and the more water you create.

For our batch size 0.7 litres of water out of 1041 litres of oil isn't too bad.

However we must take into account how much FFA we converted.

This brings me to the other item I think might be overlooked. So that figure of 2.9g/l neutralizing a 2.6ml titration makes me wonder how much sulfuric acid are we neutralizing vs how much FFA are we converting to soap.

Plus when I titrate after adding all of that methanol, wouldn't the titration be "diluted".

From my understanding, a titration is measuring the g/L to neutralize all acids.

So if the reactor had 1041L of oil and titrates a 6.7ml and we add another 132L of methanol and a 1L of sulfuric acid and end up with a titration of 2.6ml we really need to understand that the 2.6ml is misleading.

What is the real titration if the methanol dilutes it?

If we titrate at 6.7 on 1041L of oil we need 6.7g NaOH/L to neutralize that oil.

If we add 35 gallons of methanol and titrate a 2.6ml it is really 2.6g/L on 1173L.

So if you work out percentages.

1041L at 6.7ml 0.1N NaOH = 5.13% FFA or 53.4L FFA.
1173L at 2.6ml 0.1N NaOH = 1.99% FFA or 23.3L FFA.

In this reaction we have reduced the FFA from 5.13% to 1.99%. This however is a reduction of the acid value and not necessarily the free fatty acid content.

So how much FFA is an FFA reduction and how much is from sulfuric acid?

Since we know how much acid we are adding we can work out how much of the titration is from the sulfuric acid, the rest must be FFA.

Above I explained that 0.8g of NaOH will neutralize 1.0g H2SO4. Since 1L 93% H2SO4 weighs 1711g we will need 1368g of 95% NaOH.

That 1368 grams would need to be spread out of 1173L of liquid to bring it to a neutral pH.

So 1368g / 1173L = 1.16g/L, this tells us that our 2.6ml titration should really be treated as a 1.44ml when determining remaining FFA content, yield, etc.

So instead of a 1.99% FFA value, it would be closer to 1.10% or 12.9L FFA.

THIS MEANS THERE IS A MINIMUM TITRATION FOR ACID ESTERIFICATION DEPENDING ON INITIAL VOLUME OF SULFURIC ACID. MEANING IF YOU TITRATE AT THE MINIMUM YOU HAVE CONVERTED ALMOST 100% FFA TO METHYL ESTER.

Another thing to note is that when you put 5g/L in the solution for the base reaction to occur it is based on the volume of oil in the solution, not the methanol. The error occurs when you take your ending titration after esterification. This value is correct for your current volume to neutralize the acids, but isn't correct for the base reaction.

So you really want to calculate H2SO4/FFA neutralization at the current titration with the current volume, weight, etc.

Then add the 5g/L figure, but only for the initial volume of oil.

In my case, 2.6ml means 2.6g/L * 1173L or 3kg.

Then 5g/L for 1041L or 5.2kg.

This brings us to the total of 8.2kg.

I have seen references to mutiplying the titration by 1.1 to account for this discrepancy but I prefer to be more accurate when it isn't a bother.

I'm getting sleepy and these numbers are getting fuzzy, I'll have to revise the post tomorrow when I'm a bit more alert.

I have been working on a "Super Catalyst Calculator" in Google docs that takes all of this into account as well as formulations for both lye and sodium methylate.

--
Jeff Brandt
Sun Break BioStudio, LLC
http://www.sunbreakbiofuels.com
mailto:jeffb@sunbreakbiofuels.com
 
Registered: March 21, 2006Reply With QuoteReport This Post
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interesting thoughts on the some the chemical details..

I'm sure you are aware the 0.1N isn't what's the formula is base on..its based on 0.1%. also written KOH not NaOH..so if you're using 0.1N for titration the 0.2ml/L will be wrong..
but which way??

sorry if but I have to work this out...

KOH - 56g/mol.
so for a 0.1N solution we would use 5.6g in 1 liter of water..

homebrew uses 1g in 1 liter so the 0.1N titration would result a lower titration for the same oil because it 5.6 times stronger.

now trying to put numbers with this

0.1% homebrew titration 15
0.1N titration I would guess would be 5 times less or 3(round involved!!).

ending titration is a little bit misleading. since you don't get to pick the end. for homebrew using KOH is typically 3

so for homebrew
15-3 = 12 * 0.2 = 2.4ml/L of acid

for 0.1N titration
ending if it was homebrew would be 1/5 of 3 or 0.6
so 3 - 0.6 = 2.4 * 0.2 = 0.48 or much less acid

interesting..but I know that 0.2ml works and works well..

my method is also based on FATTA and ISU. for this reason I didn't try to copyright or patent it. I gave it back freely because so many helped me when I was learning.

its also interesting that you add the acid to the oil first. I don't I add the acid to the methanol..i wonder what if any chemical reactions happen between the acid the methanol? what about reaction with the oil and the acid?

-dkenny


'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died..Frown 8.23.11 bus driven to scrap yard Frown )
2006 Jeep Liberty CRD Smile - the wife's
99 dodge 2500 5.9l 24v..-mine Smile
everything run B100 when its warm enough Smile
 
Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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