WFU Biofuels

Wake Forest students, faculty, staff and associates making and testing vegetable-oil based fuels.

Wednesday, January 10, 2007

The Educating of Ricky Bobby

After my Ricky Bobby with the MeOH I thought maybe I need to step back and educate myself on dealing with larger amounts of liquids before I start NASCAR racing.

Yes we pick the coldest days to work, it was about 0 deg C out side!!! So Dave, Miles and myself got out to Corkey's about 9:30 am Tuesday and heated about 120 gallons of oil to 50 C. It took close to 2 hours. But then again everything we do out there takes about two hours. We added two coffee cans of magansol and pumped and stirred for about 30 minutes. One really neat observation was the state of the oil before we started it was very cloudy it also smelled rancid. After the magnasol was dumped in the smell went away very quickly. The final oil was clear and smelled like normal used oil. We tired to filter with no gravity pressure but found this to be really slow so we went to using the liquid's gravity head pressure to filter with a 50 micron sock. After about an hour we had close to 40 gallons. We were all cold and needing to do some "real" work so we called it a day. There's still about 80 gallons in the reactor (the pipes were drained out) that can be heated and filtered when we want more oil.

Now for the good stuff:
I brought a sample of oil into lab, I wanted to do the reaction as close as possible to the conditions we will see at Corky's. The oil titrated it to a very consistent 2.6 meaning we need 4.9 g + 2.6g = 7.5 g KOH/L of oil. This is about average for used oil. For my 0.2 liter I need 1.52 g KOH. I brought 200 mL of oil to 55 C and added 50 mL of MeOH with 1.52g KOH. The temperature dropped to 50C when the room temperature methoxide was added. On a cold day this temperature drop will need to be addressed. Do we warm the MeOH??? I can hear it now, "Help Jesus, Help me Allah, help me Jewish God, help me Tom Cruise!!!" Anyway, the reaction was insulated with bubble wrap, my new toy toy since Dave told me I wrap up in it to stay warm, and left stir for 3 hours. Next, I wanted to try the 5% prewash method lots of folks are using
The crude mixture was transferred to a separatory funnel and allowed to settle for 15 minutes. The bottom glycerin layer was then set aside. A 10 mL (~10%) water wash was performed where about 20 mL of aqueous liquid was collected over 30 minutes. I should have added the water to the crude reaction and then separated but I wanted the glycerin without water for other reasons. The cloudy biodiesel layer was then stirred and air bubbled overnight to remove the MeOH. This morning it was crystal clear!!! I went ahead and added 0.25 g of Magnasol stirred and filtered at room temperature. I ran a 13C NMR and I can say it is >95% pure. I could not see any MeOH or unreacted oil. I can't say it meets ASTM but should be close.
So now we just need to scale up. I have a few more things to do on the small 40 gallon reactor and I will give this a shot. Hopefully we can get a few gallons produced to pay our electricity bill!!!!!


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