Is there an alternative to methanol?

[yaric008]

Well i was just wondering if there was any other substance that could be used to make biodiesel. First off methanol is very toxic and hard to handle, but it also comes from fossil fuels. So is there anything that is maybe safer and comes from renewable resources? Like ethanol or something?

[IanOMechura]

I read somewhere that you could use ethanol instead but the process may be more difficult.

Ian

[Ford_Forgotton]

you can, but its MUCH HARDER! The following is from journeytoforever.org

[ QUOTE ]
Ethanol-based Biodiesel

1. Get plenty of experience making biodiesel with methanol before you try it with ethanol. Get comfortable titrating your oil for FFAs (free fatty acids); you?ll need to do that when you use ethanol.

2. Try to find a source of KOH (potassium hydroxide) to use instead of lye with ethanol. Lye (NaOH, sodium hydroxide) will work, but it dissolves VERY slowly in ethanol. You'll need to use more of either one -- 7g per liter of clean oil with NaOH, 10g per liter of clean oil with KOH. More as required per your titration level.

3. Your ethanol will have to be EXTREMELY dry. 199-proof or higher. "Absolute" ethanol. Any more than one half of one percent water can kill the reaction. Denaturants like methanol, isopropyl alcohol, MIBK, etc., are fine. But no water. Ethanol that dry is difficult to find cheap, especially in the US. If you want to try to make it yourself, you'll need molecular sieve, quicklime, or something else to do a "chemical" drying. Distillation alone can't get the water under 5% -- still way too much. (See below -- Anhydrous ethanol)

4. If you're interested in ethanol for environmental reasons, be careful. Even if you find anhydrous ethanol, it may come from fossil fuel. The denatured alcohols used by painters, or in other industrial applications, may be anhydrous but still derived from petroleum. In fact, since fermentation uses water, it's cheaper to make 200-proof starting with petroleum. The only way to know is to call the original manufacturer of the formula. Ask if the ethanol is "synthetic" or "fermentation". One type of denatured anhydrous ethanol that is almost always fermented is "fuel-grade", which is 199-proof denatured with gasoline. It's what they add to gasoline to make gasohol.

5. Your oil will also have to be EXTREMELY dry. Heat the oil to 120 deg C (248 deg F) and hold it there until you can turn off the flame and see the bubbling stop almost immediately. You might want to throw in some clumping cat litter (bentonite clay) and/or silica gel to scarf up any remaining water, let it settle half a day, and take the oil off the top. Sometimes that's still not dry enough. Remember -- any more than 0.5% water can kill the reaction.

6. Your oil will have to be fairly low in FFAs. You'll want to do a titration on every batch to make sure. Anything over 2 ml titration (using 0.1% NaOH solution) can cause failure of the glycerine to separate -- under 1 ml is a good idea. Most waste oil is too high, and either needs to be refined with NaOH first, or cut with clean oil to neutralize FFAs.

7. You need to use more ethanol to get full conversion. Somewhere between 275 and 300 ml per liter of oil is about right for most oils. Coconut oil will need more, maybe 350 ml. Theoretical is about 180 ml per liter, and the rest is excess to drive the reaction all the way.

8. Even when you do all the above, getting the glycerine to separate is a matter of good luck and fervent prayer. Sometimes separation occurs just like a methanol batch. Other times you won't start seeing a glycerine layer for 3 or 4 hours, or maybe overnight. Then again, sometimes it NEVER separates. Until you get separation, you haven't made biodiesel. I've heard of folks who don't wait for separation -- they just pour the whole mess right into the tank, or do some kind of water wash and think it's good biodiesel. It might burn, but it's not biodiesel. It must separate.

9. If it doesn't separate, you can sometimes force it by adding some methoxide mix. You can also make it more likely to separate by including some methanol with the ethanol right from the start. For example, you could try using an initial mix of 5 to 7 parts ethanol and 1 part methanol. Give it a few hours to separate. If it doesn't, add some straight methoxide to the kettle, using enough methanol to bring the alcohols ratio down to 3:1 eth:meth, and containing another 2g of KOH per liter of oil. That usually initiates separation within an hour. Fresh, refined edible oil might even work the first time with straight ethanol. If you use a mixture of ethanol and methanol, you can get away with 275 ml of initial mix per liter of oil.

10. If you're not scared off yet, Good Luck!
-- Ken Provost

[/ QUOTE ]

[yaric008]

Hm.. i wonder if something besides ethanol can be used. Don't know what but just it seems like using methanol almost cancels out the reason for using biodiesel - to not use fossil fuel. Still i guess, it's better than pure fossil fuel diesel.

[Wapitibill]

Most methanol is made from natural gas. While technically gas is a "fossil fuel," it isn't quite the same as using imported oil as a feedstock.

[Ford_Forgotton]

Your methanol can also be "recovered". Your not burning the methanol in the vehicle, only using it as a carrier for the lye so that the lye can react with the glycerine.

In theory, if you had 100% recovery of your methanol via distilation, you would only have to purchase your methanol supply once.

Methanol distilation temp is only 160 degrees, well below that of water. You just basically setup a STILL like you would for moonshine and run all of your waste glycerin and wash water to recover your methanol.

[jdkline]

Yeah, but you can't recover all of it can you? Doesn't most of it become part of the biodiesel? It was my understanding that you replaced the glycerin with an alcohol to make an ester, and that the lye was only a catalyst for the reaction, so it can occur at room temp.

[girlmark]

[ QUOTE ]
Your methanol can also be "recovered". Your not burning the methanol in the vehicle, only using it as a carrier for the lye so that the lye can react with the glycerine.

In theory, if you had 100% recovery of your methanol via distilation, you would only have to purchase your methanol supply once.


[/ QUOTE ]

not quite right... (sorry!)
the methanol becomes part of the fuel, but the lye does not.

biodiesel= the fatty acid portion of a vegoil molecule, combined chemically with a methanol molecule

What we mean by 'recovery' is that we use excess methanol in order to make good quality biodiesel- and that excess can be recovered. The reaction uses something like 13-15% and the extra 5 or 7% that we homebrewers use can be recovered.


mark

owner of a pathetic old '83 6.9

[rockhead55]

I have idly read discussions on ethanol based bio at http://biodiesel.infopop.cc/eve/ubb.x where I have been a member since before I bought a diesel! It might be easier than the journey to forever comments above.
I highly recommend that you go there and read up on ethanol based bio and perhaps try a few microbatches by adapting the "Dr Pepper Method" (TM) to ethanol.

I have never made bio [img]/ubbthreads/images/graemlins/eek.gif[/img] but I have studied chemistry [img]/ubbthreads/images/graemlins/smokin.gif[/img] and would like to point out the following :
Alcohol (methyl ethyl or propyl) is consumed in the reaction, having an excess will allow higher product yields.
NaOH or KOH are reagents not catalyst. The difference is that there is consumption of these whereas a true catalyst is not consumed. Were these actual catalysts they could be added in any volume rather than titrated amounts.
The reaction dynamics for ethanol based bio may be entirely different from methanol based. You can safely heat ethanol to higher temps, it has lower toxicity and will undoubtedly react with differences with our so called catalysts.
You should read thoroughly before diving into this and work from knowledge rather than random inquiry. Random inquiry can be dangerous in chemistry.

Glenn

[girlmark]

That is correct about titration and catalysts in general, but in our case we have more than one reaction going on.

Biodiesel catalyst and titration in a nutshell:
The main reaction that we want, is between the triglycerides (oil) and methanol or other alcohol (ethanol is the second most usable). The result is biodiesel and glycerol. Lye (NaOH, alternately, you can use KOH) is a catalyst in this case, and we use between 3.5 and 5 grams of it for every liter of oil, to catalyse the reaction. The lye passes through the reaction unchanged and is found mostly in the glycerol after the reaction is complete.

The side reaction is between lye and free fatty acids (which are what makes the waste restaurant oil rancid and taste/smell bad, and be bad for our some metals in fuel systems). The side reaction makes soap, some of which is in the glycerol layer and some of which is in the biodiesel until you water wash the biodiesel.

We have to do a very simple 'titration' (or "acid number") test in order to find out how much of our lye will get consumed as a reactant in the side reaction. We then add this extra lye so that we will still have 3.5-5 left over after the side reaction. This 3.5 to 5 grams will be enough to catalyse the main biodiesel reaction.


Mark

[jdkline]

Welcome to the Diesel Stop. We all appreciate your expertise. The rest of you all should listen to girl Mark. I've read her stuff on other sites and she's made a lot of biodiesel. I do have to take issue with you on one thing, an '83 6.9 is not pathetic its....vintage [img]/ubbthreads/images/graemlins/laugh.gif[/img]