Transcript PowerPoint Presentation - Biodiesel Lecture

Running a Vehicle Off of Waste
Producing Biodiesel from Used Vegetable Oil
Class:
Teacher:
Fellow: Jennie Ohayon
Date:
Running a Bus on Vegetable Oil
•The stored energy in
vegetable oil can power a
vehicle
•A diesel engine will run on
straight vegetable oil, but oil
needs to be heated prior to
use
•Biodiesel can be used in any
diesel engine with no
modifications to the vehicle.
•Due to difference in viscosity
Biodiesel Production
• Requires vegetable oil, an alcohol
(methanol) and a catalyst (KOH)
Glycerol
3 Fatty Acids
H
H
O
H
C
O
C CH2 CH2 CH3
O
H
C
O
H
C
O
C
CH2 CH2 CH3
C
CH2 CH2 CH3
O
H
+
3 H3C
Methanol
Catalyst
(KOH)
OH
H
C
OH
H
C
OH
H
C
OH
O
3 H3C
O
C CH2 CH2 CH3
Biodiesel
Trigylceride
Figure 2. The reaction of a Triglyceride to Biodiesel and Glycerol
+
H
Glycerol
Biodiesel Production
Triglyceride
Biodiesel
Fatty Acid Chain
Glycerol
Catalyst (KOH)
Methanol
Glycerol
Products of Reaction
• Biodiesel
• Glycerine
• Why do they
separate?
• Because they
separate, we can
easily drain off the
glycerine and be
left with biodiesel!
Biodiesel
Glycerine
The Politics of Biofuels
• What might be
some of the
environmental and
social benefits of
biofuels?
• What might be
some of the
negative impacts
of biofuels?
Producing Biodiesel from Waste Oil
• How does
producing biodiesel
from waste oil
affect the
environment?
• How does it affect
the chemical
reaction?
Methanol
Free Fatty Acids Interfere
With Biodiesel Production
Soap
Glycerol
Free Fatty Acid
Catalyst (KOH)
Methanol
Glycerol
Media Coverage of Schools
Producing Biodiesel
“Galway students convert vegetable oil into
biodiesel fuel.” The Saratogian 15 January
2011
Making Biodiesel at
Watsonville High School!
The End… Ready to Make
Biodiesel?
Day 2; Teacher Notes for Introducing Part II of Lab
• If they did a great job the first part of lab, let them know; let
them know if biodiesel and glycerine separated in their
batches
• Recap what we did last week- What did we mix together?;
What are the products? What does the potassium hydroxide
do?
• Read over introductory text from Part II of lab handout
• Show one of the group’s biodiesel; ask them which is the
biodiesel layer and which is the glycerine
• The glycerine layer is on the bottom (discuss density)
• We will remove the glycerine today; we just want the biodiesel
(I will compost the glycerine as it biodegrades quickly)
Day 2; Teacher Notes for Introducing Part II of Lab
• Then we will wash it with water
• Much of the soap and glycerine produced, as well as any
excess catalyst and alcohol, has settled out of the
biodiesel layer
• However, even after 12 or 24 hours of settling there is
still some left in the biodiesel fraction and this is why we
wash it
• The water will remove impurities suspended in the
biodiesel layer, including excess catalyst, soap,
methanol and glycerine (they dissolve more readily in
water than in biodiesel)
Day 2; Teacher Notes for Introducing Part II of Lab
• If the biodiesel reaction worked well, then when we wash
it , the water should separate quickly from the biodiesel
(and then we can drain off the water, the same way we
drained off the glycerine)
• We will wash the biodiesel at least five times; follow the
procedure in your lab handout and make sure everyone
gets the chance to wash it at least once
• If your biodiesel does not separate quickly into two
layers or there is a thick white foamy layer in between
the glycerine and biodiesel, then we would not want to
use this biodiesel in our car (we need more practice with
the biodiesel process)
Day 2; Teacher Notes for Introducing Part II of Lab
• If it does not separate quickly (see lecture notes from Day 1
for discussion on emulsion), then this is likely the result of
either an incomplete reaction or too much soap
• Emulsifiers are used to make stable mixtures of water and oil
(like mayonnaise!)
• Recap free fatty acid discussion from first part (see lecture
notes from Day 1)
• We added an excess of catalyst, because we know it will
react with the degraded oil to produce soap and we want
enough to be left over to catalyze the biodiesel reaction
(recap from first day)
• Too much soap being produced can lead to an emulsion when
vigorously mixing the biodiesel and water together
• An incomplete reaction with poor conversion might have left
us with half-processed monoglycerides and diglycerides;
these are fuel contaminants that also act as emulsifiers.