I ca«t be too sure on my answer, but wouldn«t it bee too dense?
First of all, it wouldn«t be a transesterification, as the
transesterification implies:
ROH + R«COOR«« -- R««OH + R«COOR
i.e., switching the carbon chains between an ester and an alcohol.
You«d be esterifying the glycerin:
C3H5(OH)3 + RCOOH -- C3H5(OCOR)3 + H2O
Thus forming a triglicerid, the main constituent of vegetable oils, only
that in vegetable oils the fatty acid chains have 14, 16, 18, 20, (etc)
carbons, plus insaturations.
Acetic acid cas only 2 carbons, and would yield:
C3H5(OCOCH3)3 (triacetato de glicerilo, in spanish)
I suppose this substance would have properties similar to oils in some
aspects, but it lacks double bonds, so it would probably be solid. The fatty
acid chains extend in a linear pattern, evidently in zig-zag, due to the
tetrahedic bonds, so these molecules fit weel into one another. The double
bonds in oils make the carbon chains crooked, so molecules have a harder
time regrouping into an ordered consistency (solid state). Therefore, more
insaturations usually make it more difficult for the molecules to pack. So,
the bottom line is: more insaturations reduce the fusion point of greases
oils.
No saturations: /\/\/\/\/\/\/\/\/\/\COOH
The structure you propose:
CH2/\/\
CH/\/\
CH2/\/\
Seems to me would solid or of difficult flow. (I«m not an expert in this).
Anyway, don«t let these words bring down your morale. I«m not an expert, as
I«ve said, and it would be good to try this out to see what the results are.
All the best,
Christian
- Original Message -
From: Mccall Tom WP US [EMAIL PROTECTED]
To: biofuel@yahoogroups.com
Sent: Tuesday, May 14, 2002 2:09 PM
Subject: RE: [biofuel] Stoichiometric values (to Ken from Phillipines)
I there any way to transesterfy the
Glycerin?
It has 3 -OH groups I would think that you
could esterfy with Acetic acid.
If you esterfied all 3 -OH groups you would
have a C9 hydrocarbon with 6 oxygens.
Talk about an oxygenated fuel.
I think that a C-9 is close to the size
of gasoline fuels...?
Could this be a oxygenated additive for
gasoline engines.
Maybe 3-5% Biodiesal would also help to lower
emissions and make up for the BTU loss when
you add the esterfied glycerin to the tank.
Just thinking (typing) out loud.
T
-Original Message-
From: Christian [mailto:[EMAIL PROTECTED]
Sent: Tuesday, May 14, 2002 10:43 AM
To: biofuel@yahoogroups.com
Subject: [biofuel] Stoichiometric values (to Ken from Phillipines)
Hi Ken,
I«ve had my doubts on the stoichiometric values since a beginning (not that
they were wrong or anything, I was just curious), but I never had the tiem
to write it down on paper.
We could briefly try it here, assuming you«ve got the percentages of FA in
coconut oil is as you«ve described:
The corresponding fatty acids are:
46% C12H24O
18% C14H28O
10% C16H32O
4% C18H36O
6% C18H34O
But for each FA chain on the glyceol, there is one H lost in the
esterification, together with the OH group of the glycerin. We«ll assume no
FFA.
So the ester chain in the triglicerid will be as follows:
46% C12H23O = 183 g
18% C14H27O = 211 g
10% C16H31O = 239 g
4% C18H35O = 267 g
6% C18H33O = 261 g
And the glycerol bit will weigh:
CH2-CH-CH2 = 41 g
I suppose we can the say that 1 Mole of WVO (Coconut) will have:
41g + (0.46x183 + 0.18x211 + 0.1x239 + 0.04x267 + 0.06x261) = 213.4 g
Methanol weighs: CH3OH = 32 g/mol
Glyc-R-R«-R«« --(CH3ONa)-- Glyc + ROCH3 + R«OCH3 + R««OCH3 + Na(+)
But we could assume that one mole of WVO will require one mole of Methanol,
as the methyl group in it is exactly what will join the FA in the
transesterification
So every 213.4g of WVO will require 32g of Methanol
Coconut oil«s density at 20¼C is close to 0.919 g/ml (or so I read on the
internet). So 213.4 g (1 mole) will equal 232.201 ml.
On the other side, the density for methanol is 0.79, so 32g of methanol
represent 40.5063 ml.
So, 40.5063 ml in 232.201 ml represent 17.44
The proposed value (M. Pelly«s recipe) is 20% by volume. The value we got to
here is 17.44%
That«s only 2.56% shorter than the proposed value. The 20% value is useful
to push the reaction towards the products side, anyway, you should be able
to use a minimum of 17.4% methanol (in volume) to transesterify your WVO.
I use sunflower oil, and my % is even lower (close to 11% in vol).
Hope to have been of help.
Best wishes,
Christian Lenoir
- Original Message -
From: Christian [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Monday, May 13, 2002 12:39 PM
Subject: Re: Stoichiometric Balance of methanol vs glycerine
Hello Christian,
First of all i want to thank you for your posts. They have been very
helpful and informative.
I am Ken and from the Philippines. I have been making BD for a year now
thanks to this group. I use what i make because the price of BD is not
competitive to regular diesel.
I was checking the stoichiometric balance of methanol to glycerine when i
felt something