Sciencemadness Discussion Board

BIODIESEL - cheapen your gasoline

 Pages:  1  

chemoleo - 16-3-2004 at 17:31

I admit that's a bit of a catch phrase, but researchers all over the world are working on economical ways of doing this. Basically, it proabably would be economical if it was done on a large scale, with genetically engineered plants that'd produce vast amounts of oil.

In fact, biodiesel can be made easily at home, at good quality and good price, providing you can buy ethanol/methanol, vegetable oils and a base or acid such as Na/KOH or HCl in bulk.

The below information is from a friend who researched this for his diploma (with his permission), so I condensed nearly 50 pages to this. Enjoy :)


Introduction:
Vegetable oils are glycerol esters, such as mono, di and triglycerides. The acids esterifying the glycerol are long chain carboxylic acids such as oleic, palmitic, stearic acids (and many more, where variations are in the length of the chain (between 12 and 20 carbons), and the number (if any) of unsaturated bonds.
In principle, the greater the number of double bonds, the lower is the melting point & viscosity of the oil. Same goes for chain lengths.
The ester bonds of the glycerides can be broken, to yield free glycerol and free carboxylic acids. The carboxylic acids can be esterified again, with a an alcohol such as ethanol/methanol. The Metyl/ethyl esters of the fatty acids is what is referred to as Biodiesel !

The reaction equations are
Tri-glyeride (= Oil) + Methanol ---> Fatty Acid Methyl Ester (= Biodiesel) + Glycerol

MeOH + Triglyceride --> Biodiesel + Diglyceride
MeOH + Diglyceride --> Biodiesel + Monoglyceride
MeOH + Monoglyceride--> Biodiesel + Glycerine


Why is Biodiesel preferred to the conventional one?
The raw materials contain virtually no sulphur compounds, so no SO2 is produced. SO2 emissions from transport, especially from conventional diesel fuel, are responsible for a large fraction of acid rain caused by SO2 (indeed in some countries this is an issue :P)
Biodiesel contains about 10 wt-% of oxygen. This, combined with a high degree of unsaturated carbon double bonds, leads to a more complete combustion than conventional diesel fuel. CO, hydrocarbon and particle emissions are hence greatly reduced. This is especially true for less sophisticated diesel engines that have less favourable combustion conditions.
What I found VERY interesting is this: Biodiesel is completely compatible with modern diesel engines. In fact, the cetane number is even higher than with conventional diesel resulting in a smoother running of the engine.

The reaction, and reaction setup

Choice of Alcohol:
Methanol and Ethanol are equally suitable for the usage for biodiesel, but the choice has been generally methanol due to its lower cost. Butanol is another option.

Choice of Oil:
Here, Sainsbury's Rapeseed oil was chosen. Check it, it's definitely cheaper than petrol!

Choice of catalyst:
Three types of catalyst can be distinguished: alkali, acid and enzyme. Alkali-catalysed reactions are much faster (about 200 times) than acid-catalysed. However, acid-catalysed reactions can deal much better with low quality raw materials, especially oils containing significant levels of free fatty acids or moisture. Industrially acid catalysis is used (at high pressures etc) while here, KOH was the catalyst of choice due to fast reaction rates.

Lurgi Process
This alkali based process uses high quality refined vegetable oil and operates at ambient pressure and about 60 to 70 °C.
The purpose of the reflux condenser was to prevent evaporating methanol escape from the reactor, especially at higher temperatures and/or longer reaction times.

The setup is shown below:


The oil comprised betw. 80 and 90% of the reaction, depending on conditions (see below).

Molar ratios of oil vs methanol:


It can be seen that a decent excess of alcohol vs oil is desired, to achieve fast conversion. I have to find out whether the ratio 6:1 refers to methanol vs triglyceride or methanol vs fatty acid.

Effect of overall catalyst/KOH concentration


Here a final concentration of 2% (weight/weight presumably, or 0.5% per mass oil) is most desirable, at lower concentrations the conversion rate will be slow, at higher concentrations saponification will occur (which means the methylester/biodiesel is hydrolysed itself)

Effect of temperature



Here it's quite clear the higher the temp. the faster the reaction rate.


Conclusion

If you do the biodiesel production (fatty acid methyl/ethylester) yourself, aim for a 6:1 molar ratio alcohol vs vegetable oil, with 2% KOH (which is added to the reaction mix as a saturated KOH solution, to minimise H2O), and elevated temperatures.
The reaction then should be complete after 20 minutes at most.

Purification of the fatty acid methylesters (biodiesel):

This is quite simple. The heavy dense glycerol settles to the bottom of the flask, while the methyl/ethyl esters remain above





The remaining biodiesel can be neutralised with weak acids, until pH 7 is achieved (the unneutralised esters have a pH of 8.) Alternatively, and possibly preferably, the biodiesel is washed numerous times with water, and the biodiesel is decanted after the emulsion has separated into two layers.

Use of biodiesel in Combustion Engines
In this particular quest, the biodiesel was used with model combustion engines. An improved performance was shown (!!) despite the original combustion engine using an optimised oil of
25 % Castor oil
40 % Paraffin
33 % (Di-ethyl) ether
2 % Isopropyl nitrate




Anyway, I realise this is only a preliminary study (and so does the original author).
I hope nonetheless that someone tries that for himself, let's see whether you can get the old lawnmower running with biodiesel!!

[Edited on 17-3-2004 by chemoleo]

[Edited on 14-8-2011 by chemoleo]

Organikum - 16-3-2004 at 18:32

There are many people who run their diesel engines with plain vegetable oil without refining thus. (or at least a mix of 80% vegetable and 20% diesel)
There are some minor modifications necessary - a preheater for the oil and thicker fuellines - bur overall it is easy and can save a lot of money. There is a switch to change between diesel and vegetable oil - this makes starting in the wintertime easier. Most diesels have no problem at all burning the stuff.

I will try to find the (german) webpage again.....

chemoleo - 16-3-2004 at 18:56

Yah, I remember, this is what they used to do a while back, when ordinary fuel was scarce. I remember that the tractors that use vegi oil itself had a different sound/smell.

I guess the advantage of using proper biodiesel (methylated fatty acids) is that the methylesters have

a) lower viscosity
b) better flammability
c) and better ignitability at lower temp.
d) and still cheap
e) Plus, the cetane number being higher.

I am a fish - 17-3-2004 at 02:44

How does the price compare to ordinary diesel when you take taxation into account? In the UK (I'm not sure about other countries), anything used to fuel a car is subject to fuel duty.

See:
http://ww2.green-trust.org:8383/2000/biofuel/Biofuel_UK_Tax....
http://news.bbc.co.uk/1/hi/wales/2310095.stm

Al Koholic - 19-3-2004 at 19:46

I'm also fairly certain that the biodiesel fuel burns hotter than normal diesel. Yes you are eliminating oxidized S compounds, yes you have better combustion completion, but you have increased emission of NOx.

Also, on a large scale, the process becomes quite problematic in terms of over all energy efficiency, especially when compared to petrol derived diesel. The meer collection, processing, and reactions to produce a gallon of biodiesel usually make it prohibitavely energetically costly. I would say the main problem being the initial harvesing and transportation of the feedstock because it would contain such an incredibly low energy density when compared to crude.

chemoleo - 20-3-2004 at 12:45

Quote:

yes you have better combustion completion, but you have increased emission of NOx.

Why would this be? I thought, at higher temperatures, the NOx would decay?
Anyway, in some countries exhaust catalysers are used, which essentially eliminate the NOx problem (Ever noticed the pungent small coming from a non catalysed exhaust?).

With regard to cost and efficiency of processing, of course it can't complete with fossil petrols yet. The point will come, however, when the oil is used up, such renewable sources will become more feasible.
Don't forget, the petrol/oil industries had decades of research and experience, and zillions in investments, which make the production relatively cheap. If we did the same to renewable sources, I am sure such renewable energies would become economically feasible in the near future...but this is not how the dollar rolls, unfortunately...:(

Al Koholic - 20-3-2004 at 14:28

I can't find any specific mechanistic data right now on specifically how temperature affects the oxidation of atmospheric N2, but I beleive that the higher the temperature, the more N2 will be oxidized in a given time to NO/NO2. Biodiesel burns hotter than normal diesel and hence has higher NOx output.

In fact, B2, B20, and B100 are the common biodiesel fuels, the number after the B indicating the percentage of biodiesel in the fuel (which is obviously mixed with petro diesel when not B100). The B2 fuel increases NOx emissions by a very small amount while the B20 and B100 increase NOx by 2 and 10% respectively when compared to standard petrol diesel. According to http://www.agriculture.state.ia.us/biodiesel.html , the timing of the engine cycle can help to reduce the NOx emissions somewhat but it is still more than petro.

Catalysts would most definetly help and to be honest, I think advances here would help bring this issue under control in the future.

It is unfortunate that the biofuels are in the situation they are in IMHO. The expenses revealed by a thourough cost analysis sure set back their use considerably when compared to crude products but the ultimate position they will occupy in the world economy could turn out to be very pivotal when crude prices skyrocket. Investments in means of making the overall process more efficient and cost effective would surely pay off to some degree in the future oil crisis.

I am an advocate of hybridizing technologies such as solar, geothermal, wind, etc with chemical technology as I see this turning, for example solar, into a much more versitle power source. The ultimate feasibility of these options remains to be seen on a large scale but I am nearing the completion of plans to do small scale tests with solar distillation and such...

unionised - 20-3-2004 at 15:34

At the moment, here in the UK it is only cheaper to use cooking oil than diesel because you don't pay duty on cooking oil. This is ilegal. OTOH there are some people who use recycled oils and pay the duty. It still works out cheaper because they don't have to pay to have the used oil disposed of.

As the world runs out of petroleum I think there will be a shift towards renewable fuels but I'm not sure which ones they will use (methanol and hydrogen are the usual sugestions).
Here's an interesting point; the CO2 from biodiesel is more radioactive than that from traditional diesel.;)

PHILOU Zrealone - 2-6-2004 at 14:27

Yeah C14 enriched oils ;).

Actually your points are good unionised...

Why bother with vegetal oil,low molecular weight alcohols, catalyst,heat, agitation, time to react and decantate, washings and acumulate glycerol...when methanol, ethanol and aceton already are cheaper and choice fuels...

CH3-OH is a good choice
CH3-CH2-OH is a better choice
They burn too hot? Add some % water.
No NOx nor SOx troubles.
Easy available via conventional distillation.
For sure cheaper than your biodiesel because they are amongst the starting materials...you spare all the process costs.

From the above one can make...
CH2=O, CH3-CH=O and then in acidic conditions acetals like...
CH3-O-CH2-O-CH3, CH3-CH2-O-CH2-O-CH2-CH3, CH3-CH(-O-CH3)2, CH3-CH(-O-CH2-CH3)2
(Use of peroxydation inhibitors must be done to avoid peroxydes formations.)

But also...
HCO2H and CH3-CO2H
From what HCO2-CH3 (methyl formate), HCO2-CH2-CH3 (ethyl formate), CH3-CO2-CH3 (methyl acetate), CH3-CO2-CH2-CH3 (ethyl acetate)...Ahhh good smelling ester fuel...(rhum aroma-and fruity smells):P:P

Final step might be CH3-CO-CH3 from acetic acid...although it is poor overal weight yield since for every association of two molecules of ethanoic acid (acetic), you have to loose CO2 and H2O.On the other hand aceton can be obtained by fermentations too...
The later, aside with CH3-CH=O offers interesting crotonisation reactions in alakline or acidic media...
(CH3)2C=CH-CO-CH3, (CH3)2C=CH-CO-CH=C(CH3)2, CH3-CH=CH-CH=O, (CH3)2C=CH-CH=O, CH3-CH=CH-CO-CH3, CH3-CH=CH-CO-CH=CH-CH3, ...
are the potent resulting molecules.
Hydrogenation might then lead to corresponding saturated alcohols or unsaturated ones; methanol or ethanol will lead in acidic media to corresponding acetals.

So starting from fermentation you can get a lot of other cheaper bio-fuels equivalent to benzine.
*****************************************
Hydrogen is another very good alternative fuel also quite cheap and easy to make.
*****************************************
The process you exposed is simply a reaction of transesterification.... methanolisation or ethanolisation thus....

What about recycling glycerol into triformic or triacetic ester?
Tributanoic ester is major ingredient of butter...so everybody can make glycerol and butyric acid at home...the later is a good fuel except it has a stinky repulsive smell of rotten butter.

:cool::cool::cool::cool:

unionised - 2-6-2004 at 15:00

You could do any or all of those nice interesting reactions, or you could just run diesel engines on vegetable oil. I wonder which would be cheaper?
Methanol and such are only cheap because we haven't run out of oil yet.

PHILOU Zrealone - 2-6-2004 at 15:07

Methanol is made from C=O and H2 or from wood distillation...if you don't know the origin of the name methanol, it comes fomr the old latin word methus (spirit of wood).

Ethanol might be done by suggar fermentation or via ethene(oil dependant yes) hydratation with acids

So really no need of petrol oil for methanol or ethanol.
Even in the case we are runnig out of oil...methanisation of shit is a natural source of methane...
.

The_Davster - 3-6-2004 at 13:45

Quote:
Originally posted by PHILOU Zrealone
CH3-CH2-OH is a good choice


I instantly thought of Homer Simpson when I read this, remember the "one for you, one for me" -(homer fueling an ethanol fueled car):P

http://www.dangerouslaboratories.org/
This site states that when the sodium hydroxide it mixed with the methanol that sodium methoxide is formed. I was under the impression that the sodium hydroxide was a catalyst. All in all their procedure lookes like it works based on the two layes formed at the end despite getting the reaction mechanism wrong.

[Edited on 3-6-2004 by rogue chemist]

chemoleo - 3-6-2004 at 17:10

Sure, ethanol is definitely a viable alternative to the biodiesel described above.
However... the big advantage of biodiesel is that it can be used STRAIGHT on existing diesel combustion engines, while methanol/ethanol can't. That's why biodiesel gets so much attention. Plus, from rape plants (is that the word?), one not only gets glycerol and the fatty acid esters, but ALSO lots and lots of biodegradable plant mass, from which MORE ethanol/methanol can be obtained. Plus, woods (from which methanol was obtained in the past) dont grow fast enough to provide enough methanol... while rape/soy plants do.
Anyway... check this
http://www.agdepartment.com/RES/Chris%20Zygarlicke.pdf
There is alot of interesting info on biodiesel and ethanol... comparing the feasibility of each.

What I fail to understand is why most people are so reluctant to accept that biofuels are valid alternatives - just think this: If the amount of money that was invested into petrol chemistry and its rationalisation was invested into renewable fuels, then clearly renewable energies would win over - at least once conventional petrochemical fuels would run out (but then the investment would occur by necessity).
But frankly, it disgusts me. How can anyone claim that CO2 that wasnt present for millions of years, and is suddenly pumped into the atmosphere within the past 50 years, does not have any effect on our planet (like some morons in the American administration)? This 'insight' (which it is not really, as it is obvious) should be more than enough for governments to enact laws that biofuels or alternative energies should be heavily funded, and even tax-relieved to encourage the individual to use them... (and guess what, this is what happens in Germany already, with solar power... but it seems like the rare front-runner)
but I am babbling away... I guess I just had to get it off my chest! I just hate lack of foresightedness... and we (or my potential kids) and the planet has to live (or die) with it just because the governments might lose a bit money to invest on friggin military development!


[Edited on 4-6-2004 by chemoleo]

PHILOU Zrealone - 15-6-2004 at 15:15

Ethanol is already in use in some fuels of certain poor countries (Brasil)...it only needs smal adaptation of benzine motors.

For diesel...you can drive nearly with what you want as soon as it is a fuel with a moderately high flash point..here in Belgium agricultural "Tracteurs" (kind of trucks for fields and soil work, farms) run with colza oil...

I have a dream that cars run on essential oils...so earth atmosphere would be a big aromaterapy room....menthol, carvone, lavandene, pinene, limonene, thymol, vanillin,canabissol,....

No more bad smelling exhaust motor fumes...
:D:);):P:cool:

unionised - 17-6-2004 at 12:52

Nice idea, pity it doesn't work.
Once you burn pinene it isn't pinene any more and it smells of CO2 and water (ideally).
OTOH canabinol cheap enough to use as fuel is an interesting idea.

PHILOU Zrealone - 22-6-2004 at 09:42

No combustion is complete even with catalytic exhaust tube so there will be a smell of the original compound plus some other smel of derivatives ;-) and decay compounds

Tacho - 21-9-2004 at 03:33

I'm doing many experiments with biodiesel based on ricin oil and ethanol (both cheap and widely available here). However, phase separation does not seem to ocurr.

How can I test the products for the presence of the esters?

I thought about saponifing the whole thing, than only the esters would remain, hopefully floating in a separate phase, but frogfot said here:http://www.sciencemadness.org/talk/viewthread.php?tid=2282
that even water will hydrolise the esters...

Are the esters that fragile?

Any Idea?

Another question: Has anybody ever heard of a solid (non soluble or fully recoverable when reaction is over) catalyst? Something that hydrolises triglicerides?

Edit: I was thinking of a very insoluble hydroxide like CaOH in pellets, or citric acid...

Anybody out there interested in biodiesel chemistry?

[Edited on 21-9-2004 by Tacho]

vulture - 21-9-2004 at 04:08

Quote:

But frankly, it disgusts me. How can anyone claim that CO2 that wasnt present for millions of years, and is suddenly pumped into the atmosphere within the past 50 years, does not have any effect on our planet (like some morons in the American administration)? This 'insight' (which it is not really, as it is obvious) should be more than enough for governments to enact laws that biofuels or alternative energies should be heavily funded, and even tax-relieved to encourage the individual to use them... (and guess what, this is what happens in Germany already, with solar power... but it seems like the rare front-runner)


Tsk, Tsk, be careful of what you say. Biodiesel is no solution to the CO2 problem, obviously. The only worthwile solution at the moment is hydrogen produced from nuclear fission energy. Remember that fissioning 1kg of uranium saves you about 800 000kg of CO2 in the atmosphere... (taken into account both processes have the same efficiency)

JohnWW - 21-9-2004 at 12:54

I remember reading somewhere that air bubbles recovered and analysed from the Carboniferous, which began about 300 million years ago, were found to have 5 times the concentration of CO2 in them as in present-day air (and about 1½ times the present O2 concentration). At that time, and for most of Earth's geological history since then until only about 30 million years ago (Miocene, when Antarctica started to become glaciated), temperatures have usually averaged about 22ºC, compared to 15ºC now, and 7ºC at the height of the Pleistocene ice age (2 million to 12,000 years ago). There is no chance of atmospheric CO2 levels returning to what they were in the Carboniferous, because of the sequestration of enormous quantities of CO2 mostly as carbonate rocks since then, especially during the Cretaceous.

John W.

[Edited on 21-9-2004 by JohnWW]

Bio - 22-9-2004 at 04:42

Quote:
Originally posted by JohnWW
I remember reading somewhere that air bubbles recovered and analysed from the Carboniferous, which began about 300 million years ago, were found to have 5 times the concentration of CO2 in them as in present-day air (and about 1½ times the present O2 concentration). At that time, and for most of Earth's geological history since then until only about 30 million years ago (Miocene, when Antarctica started to become glaciated), temperatures have usually averaged about 22ºC, compared to 15ºC now, and 7ºC at the height of the Pleistocene ice age (2 million to 12,000 years ago). There is no chance of atmospheric CO2 levels returning to what they were in the Carboniferous, because of the sequestration of enormous quantities of CO2 mostly as carbonate rocks since then, especially during the Cretaceous.

John W.

[Edited on 21-9-2004 by JohnWW]


And the planet was covered with green material (lots of it). I read a quote Scientific American I believe, that a it would take the green material (soybean?) on a 40 acre field to make ONE gallon of gasoline.

Tacho - 22-9-2004 at 10:25

Quote:
Originally posted by Tacho
How can I test the products for the presence of the esters?

They are BOTH esters.
Quote:

Another question: Has anybody ever heard of a solid (non soluble or fully recoverable when reaction is over) catalyst? Something that hydrolises triglicerides?

LIPASE.

unionised - 22-9-2004 at 13:42

The hydroxyl group in ricinoleic acid will tend to make the phase separation less effective.

Tacho - 23-9-2004 at 03:25

I bought this medicine which is basically pig’s pancreatin. It’s made by Solvay Farma (local branch of Solvay Pharmaceuticals GmbH – Germany). Each pill should have 6.500 FIP units (?) of lipase.

I mixed one crushed pill with 10ml of soy oil and nothing happened overnight.

The references I got (chinese and american) say they used lipase from fungus, imobilized in acrilic resin. I read in the box that my pig’s lipase only cleaves fatty acids in 1 and 3 position, still, nothing, really nothing, seemed to have happened to my soy oil.

I’ll try calcium acetate + barium acetate (United States Patent 5,525,126) if they form an insoluble pellet. Maybe mix with, say, portland cement.

As for testing, I’ll have to develop TLC techniques, or some specific chromatografic technique.

Esplosivo - 23-9-2004 at 08:38

Quote:

I bought this medicine which is basically pig’s pancreatin. It’s made by Solvay Farma (local branch of Solvay Pharmaceuticals GmbH – Germany). Each pill should have 6.500 FIP units (?) of lipase.

I mixed one crushed pill with 10ml of soy oil and nothing happened overnight.

The references I got (chinese and american) say they used lipase from fungus, imobilized in acrilic resin. I read in the box that my pig’s lipase only cleaves fatty acids in 1 and 3 position, still, nothing, really nothing, seemed to have happened to my soy oil.


The fact is that the room temperature is not the optimum temperature of the enzyme, and it will take ages before any noticeable effect. If I remeber correctly the immbolized enzyme has an optimum temperature of approximately 45 deg celcius, while the free enzyme has a lower optimum temp of around 33 deg celcius - internal body temp (This reduction in temp is due to the stabilty of the enzyme. In the immobilized state the structure is far more stable.) The optimum pH is of around pH7, but it functions well up to pH8.

Therefore you will require some warming for the rxn to work. Simply heating the container in a water bath will not do, since this could denature the enzyme. I would suggest an aquarium heater as a controlled heating soure.

Tacho - 24-9-2004 at 03:06

Thanks,
I warmed the tube for 3 hours at 45ºC with no apparent results.

Either: 1) The products are an homogeneous mix that looks like the reactants; 2) Some specific condition is needed for the reaction to proceed (some gastric fluid maybe). 3) The medicine is a scam.

I'm working on a chromatographyc method to check my results with other catalysts.

When I work with methanol+ricin oil+KOH, I get separate layers easily. The same mix with soy oil is hard to tell, since the reactants have two layers that have to be kept stirred anyway.

I gave up the acetate salts idea. They will dissolve (partially) in the reactants and will pose the same isolation problems that hydroxides have.

Esplosivo - 24-9-2004 at 07:46

Quote:

2) Some specific condition is needed for the reaction to proceed (some gastric fluid maybe).


In the intestine emulsifying agents are present to help facilitate the action of the enzyme, but these are not essential. Such emuslifying agents are sodium taurocholate and sodium glycocholate. These are nothing but emulsifying agents, and therefore some form of neutal detergent which does not denaturate the enzyme could be used in your case. This is just to help you in case you would like to try the process again.

Bio - 29-9-2004 at 07:39

You might look at your temperature and try to regulate it at the pigs internal temperature. Some enzymes are heat sensitive as has already, mentioned. 45 C maybe too hot. Human Brain proteins degrade above 105 F.
Just a thought I had.

Esplosivo - 29-9-2004 at 08:36

I mentioned the fact that the immobilised enzyme has a higher stability to temperature and can therefore operate very efficiently at a temperature of 45 deg celcius, therefore faster rates of reactions are obtained than with the 'free' enzyme. In fact the 'free' enzyme denatures at such a temperature, and has an optimum temperature equal or similar to that of the internal body temp, i.e. approx 33 deg celcius.

Tacho - 29-9-2004 at 09:55

I have exposed my mix to a wide range of temperatures (all below the denaturating temp. for the protein). NOTHING happen. Has anybody actually seen lipase (or pancreatin) in action? What should I expect to see?

Should I contact the public health department and acuse the company of selling garbage?

Edit:
BTW,
CaOH does not work as catalyst, neither does sodium bissulfate, powdered zinc, urushibara nickel, oxalic acid nor caolin. Why caolin? I found somewhere that certain clays would work as catalyst for this tranesterification, so, who knows, I could get lucky.

Damm. Sodium Bissulfate should have worked. It replaces sulfuric acid so many times...

[Edited on 29-9-2004 by Tacho]

Bio - 29-9-2004 at 10:41

Lipase will form a "sludge" that lies on the bottom or the top depending on the specific gravity. Some times there is a color somtimes not.
ooops sorry about missing the temperature reference.
:)

Diglycerides to biodiesel?..looking for help

robertd - 5-1-2005 at 07:00

Hello,
Pardon my lack of background/knowledge in chemistry. I have been working with transesterfying waste fryer oils into biodiesel, and having reasonable success. Now I have found myself with access to quite a bit of by-product from a vegetable oil processing facility that I am wondering if it may be applicable for biodiesel production.
Typically biodiesel is derived from triglycerides, converted via a reaction with a catalyst (typically sodium meth oxide), into methyl esters (with glycerol as by product).
This by-product is primarily diglycerides.

Can diglycerides also be converted to methyl esters? If so, should I expect a substantial yield reduction?

Like I said, my chemistry background is minimal at best. My current yields are a function of free fatty acid content...the lower the ffa, the higher the yield per catalyst (or the more catalyst required for reaction).

Any assistance would be greatly appreciated.
-Rob

trilobite - 5-1-2005 at 09:44

The transesterification proceeds stepwise

triglyceride + methanol --> diglyceride + fatty acid methyl ester
diglyceride + methanol --> monoglyceride + fatty acid methyl ester
monoglyceride + methanol --> glycerol + fatty acid methyl ester

It should make no difference if a diglyceride is used instead of a triglyceride. Yields will be lower in the sense that the fatty acid content of diglycerides is lower compared to triglycerides, or in other words, more glycerol is produced per weight of the starting material and less methyl ester.

chemoleo - 5-1-2005 at 15:13

I merged your questions into the existing thread.

This should answer your questions, and of course trilobite is correct in his answers :)

As to your yield - of course if the free fatty acid content is high, then this can't be transesterified with the existing methods, as you can only transesterify the fatty acids that are already esterified to glycerol.
For the esterification of free fatty acids with methanol you need harsher conditions, than just methanol and catalytic amounts of sodium hydroxide.

JohnWW - 5-1-2005 at 20:43

In the case of triglyceride vegetable oils which are liquid at ordinary temperatures, and do not have to be melted to use, it should be possible to use them unaltered as a substitute for diesel, without converting them to e.g. methyl esters by reaction with sodium ethoxide (which is relatively costly to do, and poses the question of what to do with the glycerol). I believe this is already done.

Tacho - 6-1-2005 at 02:34

I’m attaching a wonderful work done by Adam Kahn about biodiesel’s chemistry. It’s very comprehensive.

I wonder why thermal cracking is not a more widely used method for producing fuels from triglycerides. The gas produced can fuel the cracking process, the lighter fractions substitute gasoline, and the heavier fractions substitute diesel. It was used in large scale in china during some war.

Before someone points that the burning of the gas produce CO2, remember that producing and refining the alcohol for transesterification requires a lot of energy. Thermal cracking also can use the most dirty and inpure triglyceride available.

Attachment: Adam_Khan_Thesis.pdf (425kB)
This file has been downloaded 2233 times


chemoleo - 6-1-2005 at 05:26

JohnWW, just in case you don't know, glycerol is a bulk product in the pharmaceutical/cosmetic industry. It certainly won't ever go to waste. Industrially it is distilled off after fat hydrolysis.

Additionally, it's been mentioned before that just plain oils can be used for diesel motors etc- but this is clearly not applicable to more sophisticated motors. Hence biodiesel.
The 'ethoxide' is not particularly costly, because all that is needed is (m)ethanol and NaOH as a catalyst. Both are bulk chemicals.

Nonetheless, of course this production scheme cannot, at this point, compete with the existing production of fossile fuels. Sadly.

JohnWW - 6-1-2005 at 13:29

Of course. Compared to use of raw liquid vegetable oils instead of diesel, production of liquid methyl or ethyl esters of the fatty acids requires at least three reaction steps, which add to the costs: the synthesis of the methyl or ethyl alcohol e.g. by distillation of wood or from natural gas or fermentation and distillation from simple carbohydrates, the production of the sodium methoxide or ethoxide by reaction with concentrated NaOH, and then the use of this to convert the fatty acid triglycerides to methyl or ethyl esters.

As for the glycerol byproduct, while it has uses in pharmaceutical products and foodstuffs, and as antifreeze, if large amounts of biodiesel were ever produced through diesel becoming unobtainable or too expensive, there could be a surplus of it beyond what the pharmaceuticals and foodstuffs etc. industries can use.

Glycerol

sathor - 24-2-2005 at 10:48

hi, i know that in the saponification reaction glycerol is obtained but i don't know how to diference it and extract it...
and the amounts that i need to use
thanks

Edit by chemoleo: Are you still wondering how? SEARCH next time before you post!

[Edited on 24-2-2005 by chemoleo]

Pyridinium - 5-6-2005 at 09:32

Quote:
Originally posted by Esplosivo
has an optimum temperature equal or similar to that of the internal body temp, i.e. approx 33 deg celcius.


Am I missing something here? I believe the internal body temp is 37 C, and I think a normal pig's may even be high as 39.

DDTea - 4-9-2005 at 09:19

At my school, the shuttle buses all burn bio-diesel. It's funny because their exhaust is so dirty :D

Off topic, but I figured it could be appreciated here.

sparkgap - 4-9-2005 at 22:38

Where I currently live, the price of one liter of gasoline is enough to buy three liters of Coca-Cola. :o Good thing the government here is now researching into cost-effective alternatives for fossil fuels. Then again, I'm still of the opinion that people should not own more than two motor vehicles...

Samosa: is the smoke black or brown? I'd tend to think their biodiesel was improperly processed...

sparky (~_~)

Nerro - 3-10-2005 at 04:10

Could there be a way to change some steps in the oxidative phosphorilation so that an excess of fatty acids is produced? and perhaps the bacteria could produce the esters with ethanol they themselves form in anaerobic respiration too! that would be very interesting!

Biodiesel

MadHatter - 24-3-2006 at 11:05

The university where I work is going over to a partial biodiesel substitute. We'll be
using an 80/20, diesel/biodiesel mix. There'll be some modifications to our vehicles.
The rubber hoses used in the fuel lines will be replaced with something on the order of
Viton.

joeflsts - 24-3-2006 at 15:49

Quote:
Originally posted by MadHatter
The university where I work is going over to a partial biodiesel substitute. We'll be
using an 80/20, diesel/biodiesel mix. There'll be some modifications to our vehicles.
The rubber hoses used in the fuel lines will be replaced with something on the order of
Viton.


Our building maintenance manager has been using 100% bio for over two years. One time this winter he had to add some traditional diesel due to very cold weather. He has determined that his cost per gallon is about $1.65.

Joe

Biodiesel that solidified

Nerro - 7-5-2006 at 06:03

Yesterday I've prepared my first ever batch of biodiesel by letting an excess of slightly alkaline (NaOH in EtOH) alcohol react with some vegetable oil. I gave it a good shake in a glass stoppered bottle and then left it to stand for a while in the sun. When I checked back a few hours later there was a nice separation between two obviously different layers, one slightly brown bottom layer of "biodiesel" and one layer of nicely transparant glycerol. I seperated the layers using a sep. funnel and put the "biodiesel" in a jar to experiment with it later. But when I opened the jar today the "biodiesel" had solidified completely into a gel that was not unlike vaseline in appearance but rather like "acidified waterglass" in the way it felt and sort of crumbled when I pushed my finger into it. It dissolved very well in a little nafta but doesn't burn very well at all.

Does anyone have similar experiences with biodiesel? And would the results have been significantly different had I used MeOH in stead of EtOH? Did I use the wrong kind of vegetable oil?

Any info on the subject would be greatly appreciated.

The_Davster - 7-5-2006 at 09:10

The bottom layer is glycerin, the upper is your biodiesel.

Cloner - 7-5-2006 at 09:11

Etoh is possible they say. Never did it myself though, and it should be more difficult to get it right. One of the problems is water. You definitely want to use dry alcohol for transesterification.

The substance you have gotten likely contains soap.

[Edited on 7-5-2006 by Cloner]

froot - 7-5-2006 at 09:49

After succsessfully making biodiesel from methanol, I've been looking around for the ethanol method, ethanol being easier to make/acquire than methanol this side of town. At the moment I'm looking for the possabilities/optimised method making ethanol from sugar and yeast with minimal water.

Here is a link I'm about to get stuck into.

triphenylphosphineoxide - 19-5-2006 at 10:31

Quote:
Originally posted by MadHatter
The university where I work is going over to a partial biodiesel substitute. We'll be
using an 80/20, diesel/biodiesel mix. There'll be some modifications to our vehicles.
The rubber hoses used in the fuel lines will be replaced with something on the order of
Viton.

Replacing fuel lines and fittings may be neccessary when burning ethyl-esters. Incomplete combustion(or hydrolysis if fuel is some how wetted) can result in ethanol being formed. Ethanol is great for drying out rubber and its older substitutes, unfortunately cracked fuel lines are not fun.
Methanol is not as effiecient at destroying the fuel lines.
Although methanol is a wee bit harder to make and the methoxide vapours are more volatile, representing something of a hazard, The methyl esters are the only way to go in older engines.

kazaa81 - 12-6-2006 at 09:50

I've basified some ethanol with NaOH, then added 1/5 of volume of vegetable oil.
I've shaken until a somewhat like small droplets formed and the entire solution became of the same color.
But then, after 2 days, still nothing happened.
On the bottom there is a yellow layer, but it's still the oil I've added and, on the top there is still the basified ethanol.

My ethanol is common store buyed, dyed pink, quite pure, used for non-food purposes.
NaOH is technical grade 98-99%. The oil I've used I think it's not the bad thing in the reaction...it's olive oil.

Why does the reaction not happen? I don't see what's wrong.

Thanks

chemoleo - 12-6-2006 at 11:16

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?

kazaa81 - 13-6-2006 at 02:53

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.

Tacho - 13-6-2006 at 03:40

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.

kazaa81 - 13-6-2006 at 03:50

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? :o

Tacho - 13-6-2006 at 06:51

Quote:
Originally posted by kazaa81
So, do you think that methanol is better because of shorter chain?
:o


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

Nerro - 13-6-2006 at 13:39

I always thought the reaction was just faster when MeOH was used...

JohnWW - 14-6-2006 at 08:13

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.

froot - 3-8-2006 at 04:42

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?

not_important - 3-8-2006 at 08:11

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.

triphenylphosphineoxide - 3-8-2006 at 08:40

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.

not_important - 3-8-2006 at 11:04

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.

froot - 3-8-2006 at 12:51

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 :o.

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...

not_important - 3-8-2006 at 14:39

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.

froot - 4-8-2006 at 08:09

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?

not_important - 4-8-2006 at 13:31

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.

froot - 4-9-2006 at 00:39

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

not_important - 4-9-2006 at 09:03

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

BioChemMajor - 15-9-2006 at 13:46

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]

joeflsts - 15-9-2006 at 16:19

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

12AX7 - 15-9-2006 at 16:37

Quote:
Originally posted by joeflsts
http://www.jbc.org/cgi/reprint/139/1/199.pdf#search=%22fract...


WTF, that didn't work at all. Fixed, ^that should work better..

joeflsts - 15-9-2006 at 17:06

Quote:
Originally posted by 12AX7
Quote:
Originally posted by joeflsts
http://www.jbc.org/cgi/reprint/139/1/199.pdf#search=%22fract...


WTF, that didn't work at all. Fixed, ^that should work better..


Thank you.. I have a hell of a time adding links.

Joe

not_important - 15-9-2006 at 21:16

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.

BioChemMajor - 16-9-2006 at 07:33

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.....:cool:

[Edited on 16-9-2006 by BioChemMajor]

not_important - 16-9-2006 at 19:55

Sawgrass to ethanol appears to be a better (higher yield) route for most regions.

Greasle

Ozone - 5-11-2006 at 13:13

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:D) to valorize it and turn a profit?

glycerol to 1,3-propanediol looks like a fairly good idea; any others?

cheers,

O3

stricnine - 10-11-2006 at 07:52

Increase people's daily cheese intake, so their intestines get clogged, and then :we can market glycerin as "Human Drano"!! (IN other words, as a laxative) LOL!! :D:D



[Edited on 10-11-2006 by stricnine]

Ozone - 13-11-2006 at 18:33

Well, glycerol is used as a stool softener, not a laxative per-se. Of interest, however, is that molasses (I mean blackstrap, not the stuff they sell for consumption, viz. "Steens"). This stuff has a very high ash content, including Mg/Ca citrates! A couple of spoonfulls (which I tried when I was naive, thinking it smelled delicious)...was able to hit the "eye of a needle at fifteen paces" (harsh!). I've thought of mixing it with bleached powdered cellulose and coating it with Nukol and marketing it is "all natural" "Molaxative".

I apologize for deviating from the thread, but my inner juvenile could not resist the anectdotal reference.

The composition of molasses, however, is of interest since the production of EtOH supports the production of greasle. Molasses is about the most complicated composition of *shit* and sugar imaginable, but with 30% fermentable carbohydrate is a viable (*cheap*) feedstock. Experimentally, we have been growing rapeseed ("canola") to compliment this process.

This is theoretically possible on the home-scale, at least, until the industry scoops up all of the molasses :(.

Best of luck to all on the homebrew,

O3

froot - 14-11-2006 at 04:36

Well glycerine could be a fuel in itself. It has a boiling point of 290 deg.C, a flashpoint of 160 deg.C and a BTU of about 97000/gallon. (reference for this: http://biodiesel.infopop.cc/eve/forums/a/tpc/f/739605551/m/1...) biodiesel having about 117000 btu/gallon.

I dont see why, with a bit of manipulation, biodiesel and glycerol cant be used as a fuel in turbine engines. With a good preheat in the combustion chamber past their respective flashpoints, they both should ignite readily when exposed to oxygen. Just think, you could go see the world and all you need is a truckload of laxative :P.
The safety aspects make it a rather attractive option compared to kerosene and it's eagerness to burn everything up.

Tacho - 14-11-2006 at 05:05

Burning glycerine produces acrolein, ranked as one of the most hazardous compounds (worst 10%) to ecosystems and human health.

I could not open the link you posted, maybe it shows a way to circunvent this problem. Sorry if that is the case.

Ozone, since you brought that very interesting point up, why don't you start a thread about possible uses for glycerine. Indeed, it seems that there will be lots of it available in the near future.

froot - 14-11-2006 at 05:37

No, that link is just my reference for the BTU of glycerol.

Well after a bit of googling, I read that acrolein autoignites at 233 deg.C or there abouts. The temperature of the gases after combustion in a turbine engine are well above 1000 deg.C. I'm pretty sure any trace of acrolein will be decomposed by secondary combustion releasing more energy.

Ps, sorry for off topic, maybe the glycerine part split off into a new topic?

[Edited on 14-11-2006 by froot]

Ozone - 14-11-2006 at 17:20

Hello all,

The *big* problem with glycerol in an internal combustion engine is the fact that the acrolein (besides toxicity and a bunch of condensation products, viz. dioxolanes from glycerol and acrolein) will polymerize fouling the hell out of everything.

I thought a new thread would be a good idea as well! I'll try to get one up.

Ozone - 14-11-2006 at 18:30

OK everyone,

I started a new thread regarding the valorization of glycerol!

See you there,

O3

DrP - 22-11-2006 at 04:52

Hi,

I wasn't sure if I should start a new thread for this question or not, so, I'll put it here.


Does anyone know anything about the antifreeze used in diesel? I'm presuming it is more sophisticated than simple ethylene glycol! So - What chemical is used as antifreeze in diesel fuel for engines?


Thanks!

Ozone - 23-11-2006 at 10:10

Depending on the weather, up to 10% EtOH can be added to (or left in!) the biodiesel; this helps to prevent gelation (without fuel warmers).

O3

tito-o-mac - 3-7-2007 at 07:36

do hydrogen fuel cells work just as well as biodiesel?

Centimeter - 27-10-2007 at 22:37

I think a lot of people confuse hydrogen as a source of energy. In truth it is looked at as more of an energy bank for transferring energy to a car where it can be mobile. If memory serves me correctly, hydrogen is the most efficient energy vector that we know of. The energy that produces the hydrogen gas comes from a different source, currently fossil fuels. It poses an interesting solution in particular if nuclear power becomes more widely used. As you can imagine, it's much easier to make a nuclear power plant generate hydrogen gas than it is to put nuclear reactors on every single car! The same would be true with solar, wind, and geothermal energy.

I wanted to address vulture's comment that biodiesel would not solve CO2 emission problems. You forget that fossil fuels are accessing carbon from carbon banks where as biodiesel, and in fact any grown fuel, accesses atmospheric carbon. The issue with fossil fuels is that we are effectively increasing atmospheric concentrations of CO2. Biodiesel would not only create a sustainable carbon cycle but could potentially, through sheer cellulose refuse, reduce atmospheric CO2 concentrations.

One issue that I've always wondered about with regards to cultivated fuels is the source of fertilizers. It is my understanding that we currently derive the majority of our fertilizers from fossil fuels. That could put a serious damper on cultivated fuels if we suck the world dry of fossil fuels, not to mention the whole issue with food. As chemists have been saying for decades, it’s a shame that we burn petroleum for such easy to find things as energy.

Intergalactic_Captain - 13-11-2007 at 21:02

A couple of articles to add to the conversation - The first one is an overview of miscellaneous pyrolytic routes to fuel from triglycerides, with a good bit on straight-up catalytic cracking. One of the things that caught my eye was the mention of "H ZSM-5" zeolite to produce highly aromatic gasoline-grade fuels...Definitely gonna do more looking into this.

The second article is from the DOE regarding their goals for biofuel production - Haven't gotten a chance to read into it in any detail yet, but it's quite long and looks like it might yeild some interesting info.

[Edited on 11-14-07 by Intergalactic_Captain]

Attachment: triglyceride pyrolysis.pdf (314kB)
This file has been downloaded 4503 times


Ozone - 13-11-2007 at 22:14

ZSM-5 and the Mobil process are quite cool, aren't they? Please check out also, a nice Fischer-Tropsch application, which I have attached here.

(see also Zeachem)

Cheers,

O3

[Edited on 14-11-2007 by Ozone]

Attachment: Lamprecht 2007.pdf (213kB)
This file has been downloaded 2037 times


Intergalactic_Captain - 14-11-2007 at 11:16

Cool - I did a little research into synthesis gas last year, but put it on the backburner due to the energy input required to produce it. Interesting part on the composition of the JP-8 fuel - at ~55% heptane, it should be a good starting point for gasoline type fuels....Gotta track down their references and see if there's anything useful.

The way I figure it, gasoline-type fuels, ie. shorter chained, more volatile hydrocarbons, are where the money's at in biofuel production. The average american thinks of biofuel as something they put in their car, not necessarily in the grander terms of the national grid and industry. As such, biodiesel doesn't fit the bill - there just aren't enough diesel cars. However, a renewable gasoline alternative that costs less than $3/gallon would get more people's attention. Even if the difference was only in the cost to the consumer, the desire for cheap gas would generate a high demand for the product. Whoever can set up for large-scale low-cost production first will end up all the richer, able to invest in other areas of research and carve out a place in the renewable fuels industry.


Here's a link to a preparation of a ZSM-5 zeolite...Looks like it might be the right one by some odd coincidence...An excerpt:

Quote:

lWeigh out about 0.510 g of sodium hydroxide pellets and finely grind with a mortar and pestle. Place this mixture in a 250 ml beaker, and add 2.01 g of silicic acid and 1.01 g of tetrapropylammonium bromide. Mix with 5.0 ml distilled water, then add 1.0 ml of n-propylamine and mix the solution again.

Place 1.0 ml of a prepared 1 molar solution of aluminum sulfate along with about 0.05 ml of the concentrated sulfuric acid in a separate 50 ml beaker. Then add the first solution to this beaker as well. Add enough distilled water to raise the volume to about 25 ml, and mix the solution (26 ml total volume) on a stir plate for ten minutes. Then transfer the solution to the Parr "Bomb" and seal it. Gently shake it, before placing in the oven. Heat the sample to 160°C and hold there for 44 hours (note how long it takes to reach 160°C). Do not worry if you cannot remove every last trace of the solid out of the beaker.

After 2 days heating, turn off the oven and remove the Parr reactor and let it cool to room temperature. Remove a small sample for x-ray analysis. If the x-ray pattern matches the expected one, see figure 2, then filter the rest of the reactant in a Buchner funnel with fine filter paper (541 grade). Wash it three times with copious amounts of water and then dry for 20 minutes on the filter paper.

You are now going to calcine the sample to remove the organic cation, so set-up the tube furnace assembly (Figure 2). Place the zeolite inside, on top of the frit in the middle of the tube, and spread out to maximize the surface area. Fit a ground glass elbow at each end, one attached to a nitrogen cylinder and the other immersed in a beaker of water, to regulate the flow of nitrogen gas. Slowly heat the tube to 500°C in increments of 50 to 100°C, when water vapor will be released, then in increments of 100 to 500°C. Heat for two hours after reaching temperature, where the tetrapropylammonium bromide will decompose to tripropylamine, propylene, and water. Cool and weigh the materials (note the weight in g). Remove another sample for x-ray analysis; how does it compare to the previous x-ray?.

Any sodium ions remaining in the zeolite will now be ion exchanged for protons to fully convert the zeolite to the acid form. The sodium product from above is placed in a 100 ml beaker, and stirred with 12.60 ml of 1 M aqueous ammonium sulfate for 15 minutes. Collect the zeolite by Buchner filtration (repeat for a total of 3 washings). Wash the product with small amounts of acetone. Then wash several times with distilled water to remove all sulfate ions. Test the washings for this anion by adding drops of an aqueous solution of BaCl2; the formation of a BaSO4 precipitate indicates the presence of the ion.

When the solution no longer produces a precipitate, wash the zeolite once more with acetone to dry it, and then dry in the oven at 120°C for 20 minutes. The acid hydrogen form of the compound is prepared by transferring the oven-dried compound to a tube furnace. Heat the ammonium zeolite for 3 hours to ensure the thermal decomposition of the NH4+ ions. Over the course of this process, the zeolite should turn from a white to brown/black to an off-white color. Cool the material and store in a desiccator to preserve the acid hydrogen form.



Seems like it could be done in an amateur lab...Perhaps not as powerful as the industrial version, but proof of concept might be enough to test its viability as a small-scale method.

ZSM-5 followup

Intergalactic_Captain - 29-11-2007 at 12:11

For anyone interested, I've found a great book on the industrial production and usage of zeolites in the petrolum industry.

"Zeolite Technology and Applications; Recent Advances," Chemical Technology Review #170, Copyright 1980 by Noyes Data Corporation, Edited by Jeanette Scotte

Tons of goodies in here...I'll be scanning what I can on the ZSM-5's and posting them (hopefully) tonight. If anyone's interested in any other zeolites, there are articles on:

Zeolites A, B, X
Zeolites L, VK-2, Phi
Zeolite Y
ZSM 4, 5, 11, 21, 23, 34, 35, 38

...Most include both production and experimental usage results. The majority of the syntheses are on the laboratory scale, with easily attainable apparati, temperature ranges, and precursors.

It's really quite an amazing book - too bad it's the library's copy...I'd highly recommend it to anyone interested in zeolite-based fuel production.



EDIT - Attached is a zip file containing several sections on ZSM-5's and a chapter on ZSM's for hydrocarbon conversion and oxidation

[Edited on 11-29-07 by Intergalactic_Captain]

Attachment: zeolites.zip (734kB)
This file has been downloaded 983 times


higher alcohols in trans reax

chemrox - 9-12-2007 at 13:22

I'm going to stick my neck out and raise a question that might have been addressed already. I looked but did not find. Would we get a better fuel if we used higher alcohols such as pentanols, octanols, etc. And if these ols could be made cheaply as from fermentation is this a worthwhile endeavor? Again, if this has been discussed please send me a PM and I'll delete this post.
CRX

not_important - 9-12-2007 at 20:18

The fist problem is that those currently can't be produced as cheaply as EtOH and fatty acids for biodiesel. Maybe with enough gene tweaking, but that's not been shown to be true.

Next would be a comparison of the entire system efficiencies of standard IC engines, diesel, the several varieties of hybrids, and pure battery operated electric. The standard automotive engine isn't that efficient, partly because it has to operate over a wide range of loading and speeds. A modern electric power plant can 60% or better, some combined cycle designs with advanced turbines or SOFC can hit 80% efficiency. Is it more efficient to do your burning in a large powerplant, where it's fairly easy to capture CO2 and pollutants, ship that power over lines, charge batteries, and drive electric motors from those batteries? Or is it better to spread the combustion out over thousands of independent small engines?

chemoleo - 10-12-2007 at 19:09

I think the idea is that the biodiesel is made organically, by energy harvested using the sun.
However I seem to have read, if we were to plant vast areas of land (country-sized) with Rapeseed and similar, we'd still not provide all the fuel necessary to still humanity's energy hunger.
I really don't understand why these genetic engineering companies haven't reported successes yet in generating plants that have minimal carbohydrate production, and maximal fatty acid yields. I mean, rape seed plants are *big*. Very little effective mass that can be used for oils in the end, mostly it's just useless plant matter. Surely this can be improved? Anyone got some data on this?

[Edited on 11-12-2007 by chemoleo]

not_important - 10-12-2007 at 20:51

You can only cut out so much carbohydrate from a plant before it has no stem or leaves. The mass doesn't got into the oil, but into the energy collectors and supporting them. The seeds don't need much oil, but given the 1 to 3 percent typical conversion of sunlight into stored energy it takes a lot of support area. On top of that is the carbon loss when going from carbohydrates (photosyntheses product) to oil - effectively 3 CHOH => 2 CH2 + H2O + CO2

This is one reason some are strongly in favour of oil producing algae, the oil content can be higher. However there is the additional infrastructure needed; the algae must be grown in sealed systems as the oil producers would be overrun by wild strains that put energy into replicating rather than making oil.

chemrox - 11-12-2007 at 15:05

I didn't realize the higher ols lagged so far behind EtOH. I thought pentanol production was a big thing for the brits dring WWII and that fermentation was the process. I'm way behind reading on this; if you know some current literature I'd like to read up.

not_important - 11-12-2007 at 18:31

Weizmann developed the acetone-butanol fermentation prior to WW-I. Because of the shortages of food it wasn't much used in England during either WW, but the US did put it into production. This is a bacterial fermentation, not yeast.

http://mmbr.asm.org/cgi/reprint/50/4/484.pdf

There are companies that claim to have breakthroughs in butanol production, http://www.butanol.com/ for example, but they talk about scaling up to 100 gallons a week pilot plant, and there are some other problems with using it as fuel http://en.wikipedia.org/wiki/Butanol_fuel

There are fermentation routes to pentanols, but SFAIK they are not as productive as the butanol one. A problem with these is that the alcohols become toxic to the bacteria at a lower concentration than ethanol with yeast, meaning you're working with a more dilute solution to pull the alcohol out of. I know that pervaporation has been looked at as a means to continuously pull the alcohols out of the mash to prevent toxic levels from building up, and gene tweaking to increase tolerance to the alcohols also has been studied.

I don't know of any fermentation where pentanols are the primary product, and in quantity to be harvested. They're the major alcohols in fusel oil, but that's a byproduct of ethanol fermentation being present at a level of less than one percent of the ethanol.

I think that doing a Web search for "alcohol-name fermentation" or "alcohol-name fuel" is the best way to get more information; what I have is a series of notes with too few references :-( .

And again, small combustion engines with varying speed and loads will be lower efficiency than those working at near constant speed, and less efficient than large scale power plants. If you want to save money or the ecology or whatever, I suspect you need to get away from IC engines as the prime motivators for vehicles.

ShadowWarrior4444 - 9-5-2008 at 15:27

The issue of using 2,5-Dimethylfuran as a gasoline alternative should be considered more closely. Recent advances have allowed its production from glucose and fructose using an acid catalyzed method.

Notable qualities:
Immiscible with water
All current internal combustion engines can use it without modification
40% higher energy density compared to ethanol
Will require +/- no modifications to the current petrol infrastructure

The only issue that seems to be blocking its use is that its toxicity has not been completely evaluated--there are some concerns that in its capacity as a metabolite of hexane, it plays a role in the neurotoxicity of said compound.

Note: http://en.wikipedia.org/wiki/Dimethylfuran

A practical lab synth of DMF would also be appreciated; my cursory digging around has not yielded much in the way of a concrete procedure. (Though, I'll likely continue in a bit more depth.)

YT2095 - 17-5-2008 at 01:00

I`v also had a go at making some Biodiesel yesterday/last night, using the formula:

100g virgin rapeseed oil
23.8g EtOH
1.43g KOH

I left it on the magnetic stirrer overnight and then a few mins to settle, and this is the result:


all in all I`m quite pleased with it :cool:

chemrox - 17-5-2008 at 21:40

Quote:
Recent advances have allowed its production from glucose and fructose using an acid catalyzed method.



Is there a technical ref for this?

ShadowWarrior4444 - 17-5-2008 at 21:48

Quote:
Originally posted by chemrox
Quote:
Recent advances have allowed its production from glucose and fructose using an acid catalyzed method.



Is there a technical ref for this?


In my thread devoted to the topic of 2,5-Dimethylfuran, which I believe you have already read. *smirk*

(https://www.sciencemadness.org/talk/viewthread.php?tid=10488)

 Pages:  1