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 might be wrong and hope maybe you can clear it up for me. > > In our reaction we need 3 moles of methanol to every mole of glycerine to > be replaced right? or 1 mole of methanol for every mole of fatty acid(be > it lauric, myristic, stearic et al). I use coconut oil and the data for > coconut oil is as follows > > C12:0 - 46% > C14:0 - 18% > C16:0 - 10% > C18:0 - 4% > C18:1 - 6% > > in short there is around 1.74 moles of glycerine for every 1000 grams of > refined coconut oil. From here i would need 5.22 moles of methanol or 210 > ml of methanol. The receipe in journey to forever says to use 200 ml of > methanol for every 1000 ml of oil and they say that has alot of excess > already. So this is my dilema, are my calculations wrong. I wonder how > Keith and the rest came up with the prescribed volume for methanol. > > Thanks and Best Regards > Ken > > > > ____________________________________________________________________________ __ > mensaje enviado desde http://www.iespana.es > emails (pop)-paginas web (espacio ilimitado)-agenda-favoritos (bookmarks)-foros -Chat > > [Non-text portions of this message have been removed] Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send "unsubscribe" messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! 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