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chemoleo
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Have you tried heating it?
How high is the water content in the ethanol?
How much NaOH did you use? Did it dissolve in the EtOH?
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kazaa81
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I've heated it but no success again.
Ethanol is 90°...so I assume has some water (aqua) in it.
I used a very small amount of NaOH, which dissolved in ethanol very slowly.
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Tacho
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Making biodiesel with ethanol is problematic.
About two years ago I got very interested in biodiesel production. The Brazilian government launched a program focusing on castor oil and ethanol.
Brazil is one of the few places where ethanol is cheaper than methanol. Being a major car fuel here, it's production is huge. It's even added to
gasoline (anhydrous) on a regular basis.
I went as far as going to symposiums and conferences. The main topic on those events was how stupid the government decision was.
Refined castor oil is too expensive and it's biodiesel does not meet most international standards (oxidation etc.)
And, biodiesel wise, ethanol is a bitch to work with. As you found out.
All the companies that were selling plants and technology to make biodiesel were claiming that they were the only ones who had the know-how of using
ethanol instead of methanol. My personal conclusion it that only one or two of them could really use it profitably. But only on large scale
production.
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kazaa81
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So, do you think that methanol is better because of shorter chain?
Unfortunately, here methanol isn't as common as ethanol.
However, I think that much people are confusing Methanol with Ethanol, or MeOH and EtOH; how is possible to get biodiesel from cold EtOH and oil,
otherwise? 
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Tacho
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| Quote: | Originally posted by kazaa81
So, do you think that methanol is better because of shorter chain?
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I don't know what makes it better.
If I had to guess, I would say ethanol mixes better with the products of the reaction, making separation much more difficult. But this is a guess
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Nerro
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I always thought the reaction was just faster when MeOH was used...
#261501 +(11351)- [X]
the \"bishop\" came to our church today
he was a fucken impostor
never once moved diagonally
courtesy of bash
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JohnWW
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| Quote: | Originally posted by Tacho
Making biodiesel with ethanol is problematic. About two years ago I got very interested in biodiesel production. The Brazilian government launched a
program focusing on castor oil and ethanol. Brazil is one of the few places where ethanol is cheaper than methanol. Being a major car fuel here, it's
production is huge. It's even added to gasoline (anhydrous) on a regular basis.
I went as far as going to symposiums and conferences. The main topic on those events was how stupid the government decision was.
Refined castor oil is too expensive and it's biodiesel does not meet most international standards (oxidation etc.)
And, biodiesel wise, ethanol is a bitch to work with. As you found out.
All the companies that were selling plants and technology to make biodiesel were claiming that they were the only ones who had the know-how of using
ethanol instead of methanol. My personal conclusion it that only one or two of them could really use it profitably. But only on large scale
production. |
If the use of ethanol (which has to be stored well to prevent mixing with water, and is costly to purify beyond the 95% constant-boiling-point
azeotrope formed with water) derived from large-scale cultivation of sugar cane was going to be economic anywhere in the world, it would be in Brazil.
But with the recent steep rises in world prices of crude oil and refined petroleum products, it, and biodiesel derived from vegetable oils or tallow,
may now becoming economically competitive, or will soon be. I read somewhere that this would happen if the price of crude oil reached $US80 per
barrel, which has nearly happened. The problem is in the expenditure of large amounts of energy in harvesting and transporting and crushing the sugar
cane, and vegetable-oil crops such as castor oil (Ricinus) or palm oil (Elaidis species).
With vegetable oils, especially highly unsaturated ones grown in cool climates, oxidation is a problem, causing rancidity and solidification due to
cross-linking of the carbon chains. "Drying" oils like linseed oil and tung oil are especially susceptible to this. They have to be stored in airtight
containers away from light, preferably with antioxidants added. The main (80%) unsaturated fatty acid in castor oil, ricinoleic acid, would be liable
to this, being similar to the linoleic and linolenic acids in linseed oil.
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froot
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Iv'e been around reading article after article involving the different processes for making biodiesel. Everyone seems to have their own method which
differs in some small way.
In an endeavour to increase yields a 2 stage "acid/base" method popped up. This method involves the esterification of unwanted FFA's in an acidic
medium, then the transesterification using the normal alkaline catalyst. BUT, From my experience and many other reports the acid stage has complicated
the whole process leading to incompletely reacted 'biodiesel' product. The main reason for this seems to be from the water component produced from the
esterification reaction and neutralisation of the acid during the base stage. Bottom line, we don't want water in this process at all.
So the apparent benefits of esterification are cancelled by it's very own reaction product.
My questions are....
What happens to unwanted FFA's when just the predescribed base catalysis is employed?
Can FFA's can be combined with a glycerine molecule to form a polyglyceride which is then converted to a fatty acid methyl ester?
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not_important
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Combining FFAs with glycerol is an esterification, so you're stuch with doing that one way or another.
FFAs will react with and destroy the alkaline catalyst, requiring more of it and forming water.
FFAs could be removed first with a basic ion exchange resin, from which the would need to be stripped using strong base to regenerate the resin in a
separate stage.
Or you could try adding a liitle free glycerol and a solid acid catalyst, such as sulfonated polystryrene, and removing the water formed by warming
under vacuum to force the reaction. Then filter out the solid catalyst to use over. Oversimplification, but shows the concept.
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triphenylphosphineoxide
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If your prepared to redry the oil FFAs can be removed by washing with a basic soution. They will deprotonate and hence have a preference for the
water.
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not_important
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Problem with the alkaline water wash is that the FFA salts function as surface agents and soaps, possibly promoting the formation of emulsions and
making separation of the phases difficult. Monoglycerides will give similar effects.
You'll want to use a fairly mild base, sodium carbonate or bicarbonate. Hydroxide is going to promote the hydrolysis of the fats, depending on contact
time and temperature. Even carbonate will do that, but it's slower.
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froot
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Thanks for the tips, never seen them mentioned before, except the dry acid part where I read about people suggested using chemicals like sulfonyl
chloride and P2O5 .
Defeats the point a bit considering the topic name.
While I'm googling ion exchange resin, anybody done esterification reactions with sulfamic acid, cyanuric acid or or TCCA?
Water is the enemy.... what to do, what to do...
We salute the improvement of the human genome by honoring those who remove themselves from it.
Of necessity, this honor is generally bestowed posthumously. - www.darwinawards.com |
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not_important
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Sulfamic acid works, but slowly come apart from the water formed.
Cyanuric acid and TCCA aren't really any good, they are rather reactive materials and not that strong of acids. For industrial esterfication stick to
mineral acids, acidic ion exchange resins, acidic zeolites, and similar things. Mineral acids are cheap and common, solid 'acids' are easy to remove
from the reaction mix.
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froot
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Cool. Ok now say that I by some rare stroke of luck manage to successfully esterify the FFA's using a mineral acid and glycerine, the mix is now
acidic and contains water. I was thinking of neutralising it with calcium oxide (unslaked lime)until neutral which takes up the water to form calcium
hydroxide. (titrations here and there to get the quantities right)
After which I proceed with the traditional base catalysis.
That make sense?
We salute the improvement of the human genome by honoring those who remove themselves from it.
Of necessity, this honor is generally bestowed posthumously. - www.darwinawards.com |
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not_important
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The thing about adding CaO, while it will do as you say, is that it also generates heat; hot base will hydrolyze the glycerol esters. You either need
to add slowly enough to keep it from getting hot, or possibly to quickly add an excess that will both combine with the mineral acid and the water -
with good stirring. Filter or decant to separate solid the CaO/Ca(OH)2/Ca-salts .
I was thinking, and don't have an answer myself. Acids will promote transesterfication, too. They are not as popular outside of the lab, because of
slower reaction rates, and corrosion problems; NaOH or NaOMe won't bother steel much unless they are pretty hot, whilw H2SO4 will and HCl is worse -
chloride ions promote corrosion.
It could be possible to go with purely acid. Add a little glycerol and force esterfication by working warm under reduced pressure to pull the water
off. Then add excess of alcohol, to help force the transesterfication. Run until a little pressure and higher temperatures.
If you use a solid acid, filtering will remove and recover most of it.
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froot
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Found an article which came as a bit of a revelation regarding acid catalysis.
To sum it up it says that acid catalysis is far more effective for esterifyng FFA's to FAME's than for transesterifying TG's to FAME's, and the
reciprocal for base catalysis.
So, as I see it, you either want pure FFA's as a precurser, or pure triglycerides. A mixture of the two will probably leave you with bad yields and
suspect product.
Now I'm thinking of the possabilities of converting triglycerides in old oil to FFA's and trying the conversion to FAME's from that angle. Would there
be a reliable way to hydrolise TG's to FFA's?
Sorry... FAME = fatty acid methyl ester (biodiesel)
FFA's = free fatty acids
TG = triglycerides
We salute the improvement of the human genome by honoring those who remove themselves from it.
Of necessity, this honor is generally bestowed posthumously. - www.darwinawards.com |
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not_important
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Industry uses heat and water under pressure. Here's a brief description from someone researching alternative method
http://www.au-kbc.org/beta/bioproj2/fabstrs/babstrs/lipase_m...
http://www.arserrc.gov/techtrans/Technologies/Fats%20and%20L...
http://www.pennwalt.com/vegetable.html
These look to apply
Continuous splitting process to produce free fatty acids
http://www.freepatentsonline.com/20060047131.html
Continuous production process for ethyl esters (biodiesel)
http://www.freepatentsonline.com/20060069274.html
and a bunch of standards on handling food grade fats, including recommened temperatures
http://www.fao.org/docrep/meeting/005/W3963E/W3963E05.htm
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BioChemMajor
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just beginning chemistry so forgive me if i don't know what I am talking about, but what would be produced from fractionally distilling a crude
vegetable oil just as done with crude petrolium? Could the fractions be used (maybe after some chemical processing) as the different classes of fuels
(deisel, gasoline, kerosene, etc.)
[Edited on 15-9-2006 by BioChemMajor]
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joeflsts
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| Quote: | Originally posted by BioChemMajor
just beginning chemistry so forgive me if i don't know what I am talking about, but what would be produced from fractionally distilling a crude
vegetable oil just as done with crude petrolium? Could the fractions be used (maybe after some chemical processing) as the different classes of fuels
(deisel, gasoline, kerosene, etc.)
[Edited on 15-9-2006 by BioChemMajor] |
http://www.jbc.org/cgi/reprint/139/1/199.pdf#search=%22fractional%20distillation%20of%20vegetable%20oil%22
While this doesn't answer your answer perfectly it is a good read.
Joe
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12AX7
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WTF, that didn't work at all. Fixed, ^that should work better..
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joeflsts
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| Quote: | Originally posted by 12AX7
WTF, that didn't work at all. Fixed, ^that should work better.. |
Thank you.. I have a hell of a time adding links.
Joe
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not_important
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| Quote: | Originally posted by BioChemMajor
...what would be produced from fractionally distilling a crude vegetable oil just as done with crude petrolium? Could the fractions be used (maybe
after some chemical processing) as the different classes of fuels (deisel, gasoline, kerosene, etc.)
[Edited on 15-9-2006 by BioChemMajor] |
Originally those classes were cuts from the distallation of crude oil, simple separation based on boiling points; the hydrocarbons of varying sizes
already existed in the oil. Vegetable oils don't have that spread, being mostly triglycerides of straight chain fatty acids of 12 to 18 carbons
length. Distilling them causes breakup of the triglycerides, the staturated fatty acids aren't affected much but the glycerol decomposes. But you
don't get fractions as you do with petroleum.
While the triglycerides can be used as diesle fuel or heating oils, there are some problem. One is the viscosity of the vegetable oils, which is one
reason why the generally are converted to methyl or ethyl esters. Another is that poly-unsaturated slowly oxidise to give gums and varnishes, which
clog things up.
Nowadays petroleum is not just distilled, but processed so as to adjust the hydrocarbons to a desired range. The process known as cracking breaks
longer chain, high boiling hydrocarbons into shorter chains; some of these will be unsaturated (olefins) and some carbon formation occurs unless the
process adds hydrogen - hydrocracking and steam cracking. It can also be processed in reformers and alkylation reactors to generate specific classes
of hydrocarbons.
http://en.wikipedia.org/wiki/Cracking_%28chemistry%29
(wiki links from that page will give further information about petrochemical processing)
You can do the same sort of thing with vegetable oils, although with some modifications. Doing so will raise the cost of the products, vegetable oils
currently being more costly the crude oil may make such processing economically unattractive.
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BioChemMajor
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I cant wait for the day when the US has massive fields of hemp to supply us with biofuel. The Nation would smell so good.....
[Edited on 16-9-2006 by BioChemMajor]
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not_important
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Sawgrass to ethanol appears to be a better (higher yield) route for most regions.
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Ozone
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Greasle
In the US, there is a major drive, viz. $0.51/gal subsidy ($0.13US/L) to produce ethanol from biomass. Biomass includes readily fermentable waste
streams such as molasses, and cellulosics, including corn stover, switch grass and sugarcane bagasse. Butanol is seen in the "mix-alco" process
(Holtzapple and Granda, Tx. A&M). See also, the Zeachem process which uses a zeolite stabilized catalyst and claims to yield ethanol wihtout the
CO2 yield of fermentation.
As such, the industry here will favor the manufacture of fatty acid ethyl esters. This is rather problematic, as sterics seem to be a severe
limitation in the base catalyzed route. The acid catalyzed route works well, though, and there are many references available. Unfortunately, you must
deal with the catalyst by washing the product (which creates terrible emulsions) as acid is *bad* for an engine, and, you get 1 eq or glycerol for
every 3 of ester.
At the moment, the glycerol market stinks (there is a huge amount entering from osmotically forced fermentations). With the new biodiesel plants being
constructed here, we will literally be "up-to-our-arses" in glycerol, which under these conditions, is essentially worthless (simple
supply-and-demand).
What all countries making greasle need to consider is: What do we do with the glycerol (besides making nitrate esters ) to valorize it and turn a profit?
glycerol to 1,3-propanediol looks like a fairly good idea; any others?
cheers,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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