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First and foremost I see a lot of people doing the Acid Esterification wrong. It should only take 5 to 10 minutes for Acid Esterification and the oil shouldn't be darkened. Most people posting on this forum is not using enough methanol or acid. Per liter of oil, one should use 4-10 liters methanol and 5 to 7 ML 98% sulfuric acid. It takes me 5-10 minutes to convert 100% FFA to bio-diesel without darkening the finish product. 1. Add 7ML per liter sulfuric acid to 4-5 liters methanol. 2. Mix this acid solution with 1 liter Oil (FFA) 3. heat to almost boiling 4. use extreme Agitation for 10 minutes 5. let settle for 5 minutes 6. drain off your oil and reuse methanol for your next batch of FFA-OIL Now I will try to explain why this method is better. With the excess methanol, this eliminates the water issue. First of all during Esterification any water created doesn't cause a problem. Second, you can even start out with wet oil and it still works very well. You can reuse this methanol-acid mix over and over. To dry your methanol just use magnesium sulfate (epsom salt). You can even mix the magnesium sulfate right in with your batch but I dont do it this way. I can use the methanol acid mix about 5 times before having to dry it. Magnesium sulfate works very well to dry methanol. Magnesium sulfate is also recycled by heating to 450F 10-30 minutes . This removes the water. This method works so well you can even use it to dry your wet oil for the next (LYE Methanol) step. When doing the Exterification step with excess methanol the water is goes into your methanol which is easy to dry. Depending on how wet your oil is you might not be able to used your Methanol acid solution 5 times like I do. You may have to dry it more often depending on how wet your oil is. Using 4-5 liter methanol to one liter oil prevents the acid from attacking the oil or garbage in the oil making it dark. When you start the next LYE methanol step keep in mind your oil probably around 5% methanol. In some of my studies I used bars of soap. I shredded them up and dissolved them in water. Than I added sulfuric acid which converted the soap into 100% FFA. This was than dried and I added the methanol acid mix and heated to a near boil. This was put in a blender which was turned off and on ever 30 seconds, the on cycle being 5 seconds. In 5 minutes the Bio-diesel tritration was 1.2. I than removed the methanol from the Bio-diesel. The Bio-diesel was almost as light colored as bio-diesel made from new OIL. Since it started out with 100% FFA it was converted to Bio-Diesel using only acid Exterification. For me, the higher the FFA the better. 50% FFA = 50% less lye I need in the next Lye methonal step. <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The above method can be complicated and a little dangerous and was designed for pure FFA I am not going to argue with anyone on my first method but rather post a better and safer method. We have 100% FFA and what I posted the first time worked well for me. but for most people the below will work better. <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Recently i found a far better and safer way for high FFA oil. Here is a scaled down version. Use one liter OIL and one liter methanol. Put in 10 Millimeters of sulfuric acid in the methanol. Mix the methanol and oil together. seal the lid. Keep at room temperature and let set for 48 hours. At this point the Titration should have dropped very low. Low enough to process into Bio-diesel. Using.Using 2 liter methanol even works better especially for 50% or higher FFA oil. I was shocked that oil didn't need continued mixing or heat. This method is cheap and safe because you don't need heat and you can use your methanol over and over again. A 55 gallon drum will allow one to process 25 gallon every 2 days with hardly any work and no need to keep an eye on it. <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<EDIT on 7/20/2014 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>This message has been edited. Last edited by: Samuel, Biodiesel for cleaner air and fuel independence! (502) 272-6333 | ||
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You math is correct. Keep in mind though you will continue to use the methanol-acid mix over and over again. I am working with micro controllers so its more automated. I am able to use a small tank. X amount of Oil is pumped in and agitated for X amount of time and pumped back out and new batch oil pumped in. This cycle goes until five batches are completed. Its true though for some this might be more difficult. When using this method water is seldom a problem. If heated and agitated properly several small batches can be done very quickly. The oil also settles out fairly fast.
For selling it, yes its a problem.
Yes there is a reaction when acid is added to methanol. I am careful not to pour too much in too fast. You dont have to do this very often since you will be using the methanol-acid solution over and over. With each batch you will lose a little methanol and eventually you will have to mix some more. Acid needs to be put in slowly. If I am not badly mistaken when Sulfuric acid is mixed with methanol it does not form a new chemical compound so the fumes should be methanol and possibly and very small amount of Sulfuric acid. I believe the Sulfuric acid has a stronger bound for water than the methanol so the methanol shouldn't be taken the 2% water away from the acid causing it to fume off. If this is the case than the fumes should only be methanol which isnt that bad.
Yes you are correct. Water is created during this process but with the excess methanol its not an issue even if you start out with wet oil. I used to use 2-3ML acid to 1 liter methanol for 10 dry liters of oil and still had a big problem with water. It also took forever and the finish product was very dark and i couldn't get the tritration lower than 3. When using proper heat, hard agitation and the excess Acid and methanol I can complete batch in 5 minutes and get the titration down to around 1 even when starting out with 100% FFA. I have read some commercial processes using 10 liter Methanol to one liter oil.
Epsom salt is highly soluble in water and only slightly soluble in methanol and glycerol. Epsom salt has a stronger bound for water than Methanol so when put in Methanol it pulls the water out of it. The only way it would devolve in the water and mix in the methanol is when not enough enough Epson salt is used. Other than this a small amount will dissolve in the methanol. If the finish product(bio-Diesel) isn't washed with water you will probably have a very small amount of Epson Salt in it. When you buy Epson Salt from Walmart or most chemical company it will normally be crystallized and contain 15% to 20% water. This is useless for drying your methanol. The water needs to be baked out of it first before using it as a drying agent. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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I forgot to mention. During the Lye-methanol step water greatly reduces the yield far more than most realize. Its not hard to lose 10-20% of your product because of water. So when doing the acid exterification with excess methanol and than removing it you are dewatering you oil. This alone is why its so important to use excess methanol during the acid exterification step. I notice when I first started out and was only using 1 liter methanol to 10 liter oil during the acid exterification step the methanol would get so wet it'll settle to the bottom of my tank when normally the oil should be the one that settles to the bottom. I left this methanol and water in and of course got reduced yields. Even if one would start with dry oil, the acid exterification step produces enough water that its important to remove it. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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well you are certainly right about water from AE reducing yields. my solution to this is to recover ffa (and fuel) from glycerin and wash water. some goes back into AE (all of it if i get some good oil) the rest is blended for use in furnace, stove, old vehicles. this process isn't likely feasible for any small producers. you would need an enormous AE tank and an enormous methanol recovery unit. but you're right, i'm sure it's how many of the large producers would do it. | |||
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Samuel; From Wikipedia- Fisher-Speier Esterification- The reaction was first described...in 1895...Typical reaction times vary from 1-10 hours at 60-110 degrees centigrade. You wrote "When using proper heat, hard agaitation and excess acid and methanol I can complete batch in 5 minutes..." Are you saying that with 4-5 litres methanol, 7 milliliters concentrated sulfuric acid, 1 litre free fatty acids, heating 65 degrees centigrade or so, that you convert ffas to biodiesel in 5 minutes? | |||
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Yes. But this is using a blender. Normally one doesn't agitate near this hard so it will take more time. When I was using the blender I wasn't doing a full liter. But the ratio was the same as you mention above. When using 100 gallon tank it takes me much longer as I don't have a way to agitate it as hard as I do when using a blender. I was shocked when I did a titration and it titrated out to about 1.2 1.5. in such short time. I than left this same batch on for several hours and couldn't get less than 1.2. I dont know why but making a guess it could be the methanol with sulfuric acid that IS mixed in WITH the oil. If I remove all sulfuric acid maybe it will titrate to below 1. Converting pure FFA to bio-diesel is cheaper and Faster than using brand new oil and lye stage. With this in mind i am going to try to pressure cook my oil with water in hopes to convert it all to FFA. This way I can skip the lye stage which is costly and time consuming. I got plenty of wood for a heat source so my cost will be low. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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You 100% right. Anytime you lose some of your product to soap its not a permanent loss as long as you know how to recover the soap. Little bit of good old sulfuric acid put in the waste glycerin and your wash water convert the soaps to FFA which floats to the top. FFA burns good and is easy to convert to Bio. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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your putting methanol in a blender ?!!! is your life insurance paid up ![]() " I don't know what I don't know until I know" 1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005. | |||
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Samuel; Part of what you wrote was "the fumes should only be methanol which isn't that bad". Well, did you know that as little as 10 millilitres of methanol can cause permanent blindness in a person. 40 millilitres or so can cause death. When doing chemistry it is a good idea to look up toxicity information on the chemicals you use. Breathing in methanol fumes is as bad as drinking it. Part of making biodiesel is not breathing in the methanol or biodiesel vapour. | |||
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I hope that this has cleared up the toxicity of methanol. For the record I don't advise drinking while making Bio-diesel.This message has been edited. Last edited by: Samuel, Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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Hi, Found your post last night and made me go straight back to my lab. The process you describe has one flaw being that methyl ester dissolves in the methanol. I run your test in my reactive distillation reactor with oil witch tritration at 60KOH and in just 120 seconds the FFA doped down to .2 (tritration done on sample after spun in centrifuge). Under the right conditions the reaction happens fast. Testing the methanol and acid mixture i found my methyl esters, and none in the oil. Getting the ester out from the methanol and acid is not cost effective. The two ways i know is 1.) adding water to the mixture will make the bonds stronger between the water and methanol. Esters float to the top, but the you have all the extra water to remove from the methanol. 2.) Vacuum fraction distillation to split the methanol, water from the reaction, esters and the acid. I use a different approach, 60ml of 98% sulfuric acid slowly mixed into 350ml of methanol, Be careful when mixing large amount of sulfuric acid into methanol. It produces huge amounts of heat and fumes that you should not inhale even in the smallest quantity. Once the mixture has cooled below 35c add it to your oil not higher the 35c. close to 35c as you can but not 1deg over. mix the oil and methanol mixture until it does not separate anymore. Heat to boiling point and keep it there for one hour and tritate (settle acid and water out first). if your tritation is not below 2 (regardless of what you started with) then your oil was not dry. This process does not tolerate ANY water when you start. If no separation then you did not mix everything like you should have. Now you can run a normal base transesterification if you want. Do a 3/27 test to determine the amount of the non reacted oil. If you do not which to do a two stage process then leave to react for 8 ours at a boil, condensing the vapor of course. Depending on the FFA's you started with it can be done in less than 6 hours (more FFA's the better, low FFA (Below 12) takes 8 hours. Separate and wash with WATER. Dry wash do not work and i have used them all. They are made for base catalyst. Getting back to your way, Doing anything less than 100% FFA's is a problem with separating the methanol mixture accordingly. Do you have a solution for the problem? -Electromechanical engineer with chemistry as a hobby- | |||
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ok. I wish I was more active when this was posted. your using 4-5 liters of methanol per liter of oil..instead of 200ml? or 40-50 times the amount of methanol.. #3. heat to almost boiling..the methol/acid or the oil. if you heat the oil over 190 you'll never get the methanol/acid to mix in..yes I tried once..don't work..might in a blender scale(1L) but usless in the real world #4. what's extreme? I run a 2 minute turn on a 65gallon tank.. #6..they're mixed..in 5 minutes with extreme agitation it might not settle..in 5 minutes and you claim 100%FFA..did you make it?? since I've been making bio I've never seen oil this bad.. grease trap crap is less..ya.been there..and stinks -dkenny '84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died.. ![]() ![]() 2006 Jeep Liberty CRD ![]() 99 dodge 2500 5.9l 24v..-mine ![]() everything run B100 when its warm enough ![]() | |||
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I am not going to argue my method with anyone. We have 100% FFA and what I posted worked well for me. Recently i found a far better and safer way for high FFA oil. I am going to give you a scaled down version. Use one liter OIL and one liter methanol. Put in 10 Millimeters of sulfuric acid in the methanol. Mix the methanol and oil together. seal the lid. Keep at room temperature and let set for 48 hours. At this point the Titration should have dropped very low. Low enough to process into Bio-deisel.Using 2 liter methanol even works better especially for 50% or higher FFA oil. I was shocked that oil didnt need continued mixng or heat. This method is cheap and safe because you dont need heat and you can use your methanol over and over again. A 55 gallon drum will allow one to process 25 gallon every 2 days with hardly any work and no need to keep an eye on it. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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that is correct. I didnt say before but one must use 7ml acid in each liter. First of all i am no longer use this method. I posted a newer method that works better.
148.5 °F is the most you can heat it.. i normally keep it to 135f. even 100f is fine but i didnt know that at the time.
Blender is extreme
In a large tank it may take longer to settle. Yes I make the FFA for testing. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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well.. you should also mention that using a blender is DANGEROUS!! sparks and methanol tend to not get along..ie bang! fire..or BOOM..ever been around a methanol BOOM/ I HAVE..it wasn't fun either..so skip the blender.. so I would suggest skipping using a blender..IE a universal motor mixing device..like BioTom ask is your life insurance up to date? since 100% don't exist why make them.. it possible to process 80% already..done that.. it stinks..by they way.. now to counter what I've said.. conjecture this..take bad oil..make to worse to the limit..100%FFA.. then process..using AE..many stages of AE.. been there..yea many stages of AE..bang for the buck..burn it.. the return it usable fuel isn't worth the processing effort.. -dkenny '84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died.. ![]() ![]() 2006 Jeep Liberty CRD ![]() 99 dodge 2500 5.9l 24v..-mine ![]() everything run B100 when its warm enough ![]() | |||
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My blender is sealed up good.
90% to 100% is more common than you think. Some companies remove the FFa From the oil before prcess it into bio. IF this is done you will have almost 100% FFA. You batch should not stink. If it does you are not using enough methanol.
It is pointless and a waste of time doing many stages of AE. It can be done in a single batch using little heat and little agitation. I do it a different way now. read back on couple of my post and you will see what i am saying. Biodiesel for cleaner air and fuel independence! (502) 272-6333 | |||
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I am Praniesh, studying final year Industrial Biotechnology in Government College of Technology, Coimbatore. I am currently doing my project in "biodiesel production from mahua oil", the oil has a FFA% of 18. I did two step acid pretreatment using 0.35 v/v and 0.30 v/v methanol and 1% h2so4 to reduce the FFA but i could reduce it only to 4 not less than that. I tried it several times but still couldnt reduce it. I performed alkali transesterification reaction and it resulted in soap formation. So what should i do to reduce the FFA less than 1? should i change the quantity or is there any other alternative method? kindly reply me, thanks.. | |||
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don't forget to allow for the acid you used, each ml of acid/ltr of oil will result in a titration of about 2 points. so if you use 2 ml of acid/ltr then the lowest t would be 4 " I don't know what I don't know until I know" 1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005. | |||
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You know the acid esterification step, is the Fischer esterification? Where carboxylic acid + primary alcohol + strong acid catalyst plus heat yields the ester? I see no mention of conditions in your acid pretreatment. I did it in a small amount, but with a smaller percentage of free fatty acids present. When the esterification occurs in the reaction of the carboxylic acids and the primary alcohol, water is produced in an equimolar amount to the moles of free fatty acids that become esters. That water being present after the Fischer esterification is a problem for the transesterification reaction, which relies on little water being present. Water decomposes methoxide ion which causes the transesterification reaction to occur.. There is a solution to this problem but it might not be cost effective on a large scale. | |||
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