Biodiesel and SVO Forums Home
No diesel, only gel

This topic can be found at:
http://biodiesel.infopop.cc/eve/forums/a/tpc/f/9601000031/m/95310291

February 04, 2009, 02:29 PM
tomkruse
No diesel, only gel
I have tried two bathes with unused rapeseed oil - but without success.
The titration did not produced the expected result. The titration, with oil, was simulal to the blank titration ... Instant equalibrium.
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. No separation occured the fyrst 24 hours - it just gelled - like gelatine. After a week it looks like rapeoil on the top 20% down and milkshake from here to the bottom.
Do anybody have an idea why this not is working ??

tom
February 04, 2009, 03:12 PM
UFO
You didn't say how much lye you used, but 25% ethanol may be low. I've heard you need to use 30% alcohol or so, and more lye per liter as well.

How hot was the oil?


'05 CRD B100
'01 TDi B100

February 04, 2009, 03:42 PM
producer
quote:
Originally posted by tomkruse:
. . .
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. . . .


You did not use enough alcohol.

You may not have used enough catalyst.

In round numbers the molecular weight of methanol is 32 gm/mole, and for ethanol is 46 gm/mole. The "target" amount of 25% alcohol is good if you are using methanol. The amount must be adjusted up by a factor of about 44% (46/32 = 1.4375 or 44%) when using ethanol.

So 25% x 1.4375 = 36% ethanol. But! this is for pure ethanol. Since your ethanol was denatured to 93%, then you also need to adjust for the denaturant. Again, 36%/0.93 = 38.6%.

You should have used 38.6% denatured ethanol in your reaction.

Now for the catalyst.

I interpreted your value of "0,1%NaOH" to mean "the amount of catalyst I used was equal to 1/10 of 1% of the weight of the rapeseed oil." A single liter of rapeseed oil will weigh about 880 gm/mole. So 1/10 of 1% would equal 0.88 grams of NaOH per liter of oil. This is not nearly enough catalyst to drive the reaction.

In this case both the low amount of alcohol and the low amount of catalyst worked against your reaction.

If, instead, the weight of catalyst that you used was equal to 1% of the weight of the oil, then 8.8 grams of catalyst per liter of oil would be about right.

In this case the low amount of alcohol was probably your biggest problem.

You also should determine something about the denaturant used in the ethanol. If the denatuarant was regular unleaded gasoline, then the reaction (according to posts found elsewhere on this site) should have proceeded without too many problems, provided the recipe had been correct. Other types of denaturants (I don't know what those may be) may produce an adverse reaction in the transesterification reaction.
February 04, 2009, 06:57 PM
Jim D
quote:
Originally posted by producer:
So 25% x 1.4375 = 36% ethanol. But! this is for pure ethanol. Since your ethanol was denatured to 93%, then you also need to adjust for the denaturant. Again, 36%/0.93 = 38.6%.


Unless it was denatured using methanol.

-Jim
February 05, 2009, 05:15 AM
tomkruse
Thank you - all of you.
The 0,1% lye was user for titration only. The amount of pure lye desolved in the 93% ethanol was 6 gram.
I have not bee able to find the denaturation egent but on Wikipedia I found that diethylphthalat is used.
Can this agent disrupt the process ?
Or shoult I only use more ethanol ?
February 05, 2009, 05:22 AM
tomkruse
The the oil was heated to well ower 100C but the ethanol/lye mixture was not added before the oil had dropped to 55C - and the ethanol/lye mix was close to 55C also.
February 05, 2009, 11:31 AM
producer
There is a slight error in the above calculation. The specific gravity of rapeseed oil should have been accounted for in the calculation.

One liter of pure rapeseed oil will weigh about 978 gms (880 gm/mole / 0.90 specific gravity = 978 gms).

Therefore, 1% catalyst by weight = 9.78 gm (0.01 x 978 = 9.78) catalyst per liter of oil.

You used 6 grams of catalyst (I assume you used one liter of oil). Six grams of catalyst per liter of oil would be equivalent to 0.61% catalyst by weight.

Based on all these calculations you should increase your alcohol volume. You should also consider increasing your catalyst weight, as UFO originally suggested.

I know most of this is extraneous information, but since I made the error I just thought it should be corrected.

ps: Also, if the ethanol denaturant was methanol (good call, Jim D), then the % of denatured alcohol could be a little less than 38.6%.
February 06, 2009, 12:45 AM
HelpingHand
What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.


http://b100research.com
February 06, 2009, 01:01 PM
UFO
quote:
Originally posted by HelpingHand:
What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.
Hehehe, ethanol "denatured" with water is called Vodka Wink


'05 CRD B100
'01 TDi B100

February 06, 2009, 01:08 PM
Double D
quote:
Originally posted by UFO:
quote:
Originally posted by HelpingHand:
What was the ethanol denatured with? If it's water, you made soap. If not, perhaps consider the molar mass when determining how much ethanol to use. Density will generally vary by less than 3% for all oil, molecular mass can vary greatly. There are a couple variables to consider. Feel free to contact me directly at kristof.reiter@gmail.com to purchase a multi-feedstock, multi-alcohol calculator.
Hehehe, ethanol "denatured" with water is called Vodka Wink


At 186 proof we call it moonshine in these here mountains. Cool
February 14, 2009, 10:35 PM
SLAPPY101
quote:
Originally posted by tomkruse:
I have tried two bathes with unused rapeseed oil - but without success.
The titration did not produced the expected result. The titration, with oil, was simulal to the blank titration ... Instant equalibrium.
I used 93% denatured ethanol 25% by volume and 0,1%NaOH. No separation occured the fyrst 24 hours - it just gelled - like gelatine. After a week it looks like rapeoil on the top 20% down and milkshake from here to the bottom.
Do anybody have an idea why this not is working ??

tom


Just use methanol instead and you won't have a problem
September 04, 2012, 08:33 PM
bbarclays
Sodium hydroxide isn't a
suitable catalyst because it's not aufficiently soluble in ethanol and it
tends to promote undesirable gel and emulsion formation during
transesterification. Mad
October 04, 2012, 08:48 PM
WesleyB
I made ethyl biodiesel using 99.5% anhydrous ethanol plus potassium hydroxide catalyst plus new corn oil, it worked. I haven't tried it with sodium hydroxide catalyst.
October 23, 2017, 12:12 PM
Snork Fengidison
I also made gel using denatured ethanol that I had already from Lowes. I am a newbie just starting to learn how to make biodiesel and I just hadn't bought methanol yet. I added 100 g canola oil, 25 g denatured alcohol, and 3.5 g NaOH. I knew it wouldn't likely turn out but I was curious to see what would happen anyway.
October 23, 2017, 06:37 PM
Tilly
Hi Snork Fengidison,
Welcome to the forum,

quote:
Originally posted by Snork Fengidison:
I added 100 g canola oil, 25 g denatured alcohol, and 3.5 g NaOH.
3.5g NaOH to about 110ml canola is way too much NaOH. That will certainly make soap (gel)