Title: Synthesis of Biodiesel Fuel
1Synthesis of Biodiesel Fuel
- Synthesis of Biodiesel Fuel
- from Vegetable Oil
- References
- Pavia - p. 207 216
- - p. 194 202 (Essay Petroleum and
Fossil Fuels - Schornick
- http//classweb.gmu.edu/jschorni/chem318
2Synthesis of Biodiesel Fuel
- Background
- Fossil fuels
- Slow decay of marine animal and plant organisms
over periods of millions of years - Significant source of pollution
- Significant contributor to green house gases,
principally CO2 - High potential for environmental disasters such
as oil spills, drilling rig failures, chemical
plant explosions fire, etc. - Finite We are depleting this non recoverable
supply
3Synthesis of Biodiesel Fuel
- Background
- Biofuels Fuels produced from biological
materials - Ethanol (Gasohol)
- Starch (polymer of Glucose)
- Corn (Enzymes catalyze corn starch into glucose
- Expensive to produce
- Energy inefficient
- Produces more green house gases
- Sucrose (Fermentation of Sugar Cane Beets)
- Cellulose
- Switchgrass
- Agricultural waste, including corn stalks
- Waste wood from milling
4Synthesis of Biodiesel Fuel
- Background
- Biofuels
- Ethanol
- Syngas (CO Hydrogen converted to Alcohol)
- Utilizes wide array of Carbon-containing matter
- Municipal Waste
- Old Tires
- Agricultural Waste
- More Energy Efficient Than Ethanol
- Produces less greenhouse gases
5Synthesis of Biodiesel Fuel
- Background
- Biofuels
- Biodiesel (from fats oils, including vegetable
oil) - Farm products
- Large investment in farmland not dedicated to
food production - Net energy produced is greater than from Ethanol
but less than for cellulose - Produces more greenhouse gases than fossil fuels
- Destruction of forested areas to establish
farmland (loss of forests capacity to absorb
CO2) - New higher efficiency method emerging utilizing a
Sulfated Zirconia catalyst
6Synthesis of Biodiesel Fuel
- Background
- Biofuels
- Biodiesel (from fats oils, including vegetable
oil) - Algae
- Can produce oils for making biodiesel
- Grown in ponds or sewage waste water
- Several approaches, catalysts, self-contained
manufacturing facilities, etc. are being
investigated in search of economically viable
processes
7Synthesis of Biodiesel Fuel
- The Experiment
- In the Banana Oil experiment, an organic acid is
combined with an alcohol in a catalyzed Fischer
Esterification (condensation) reaction to produce
a mono ester - In this experiment the reverse of the process
(hydrolysis by H2O, Acid or OH- to the alcohol
and acid) is modified in a transesterification
reaction, in which an original trimester is
converted to three (3) mono esters by reaction
with an alkoxide base
8Synthesis of Biodiesel Fuel
- Analysis of Biodiesel product
- The trimester is cleaved sequentially by the
alkoxide base (a mixture of Potassium Hydroxide
and Methyl Alcohol), liberating the mono-esters
and glycerol - The Mono esters are produced sequentially because
the Alcohol/Alkoxide base has only one Hydroxyl
group - The mono esters are Fatty Acid Methyl Esters
(FAME) - The Vegetable oil and biodiesel product molecules
have variable composition - Three Methyl esters of fatty acids are formed
each with a different R group consisting of
12-18 carbons arranged in straight chains
9Synthesis of Biodiesel Fuel
- Analysis of Biodiesel product
- Thus, the computation of moles directly from the
peanut oil mass is not practical - Show the stoichiometric and mechanism reactions
- The Methyl Alcohol is in excess, but the
theoretical yield cannot be determined omit
summary table - Calculate a percent yield from the initial mass
of the Vegetable oil and the mass of the diesel
fuel product - Compare the original IR of the vegetable oil
(seep. 102 in Slayden Manual) to the biodiesel
IR
10Synthesis of Biodiesel Fuel
Alkoxide
Fatty Acid Methyl Esters (FAME)
An Alkoxide is the Conjugate Base of an
Alcohol It consists of an organic group bonded to
a negatively charged Oxygen atom Alkoxides are
strong Bases and, when R is not bulky, good
nucleophiles and good ligands
11Synthesis of Biodiesel Fuel
Trimester of Glycerol (1,2,3-propanetriol)and a
long chain fatty acid
The negative charge of the Alkoxide (Methoxide)
ion attacks the positive charge of the carbonyl
carbon atom (from the resonance dipole form of
the carbonyl group)
Alkoxide ion
Fatty Acid Methyl Ester (FAME)
Tetrahedral (sp3)Intermediate
1st Stage
Repeat for stages 2 3
The same mechanism is repeated two more times on
the 2 other ester groups of the trimester until
the final product is 3 Fatty Acid Methyl esters
(FAME) and one glycerol.The three reactions
occur sequentially.
12Synthesis of Biodiesel Fuel
- Procedure
- Reagents
- 10 mL Vegetable Oil (Crisco) A Trimester
- 2.0 mL Potassium Hydroxide/Methyl Alcohol
solution - (forms Methoxide ion, an Alkoxide ion)
- Prepare a water bath in a 150 mL beaker on a hot
plate - Heat the water bath to a temperature of 55oC
- Tare weight an empty 100 mL beaker or small cork
ring sitting on the balance to the nearest 0.001
g - Place an empty 25 mL round-bottom flask onto the
beaker top or on the cork ring - Determine the mass of the empty flask by
difference
13Synthesis of Biodiesel Fuel
- Procedure (cont)
- Place 10 mL of vegetable oil into the pre-weighed
distillation flask - Determine the mass of the flask and vegetable oil
- Determine the mass of the vegetable oil by
difference - Add 2.0 mL of the fresh KOH/CH3OH solution to
the distillation flask - Swirl the mixture to ensure a uniform solution
- Insert a small magnetic stir bar into the flask
- Attach and secure (with a blue plastic clamp) the
flask to a water-jacket condenser clamped
vertically to a ring stand - Note No need to run water through the condenser
- Lower the distillation flask into the water bath
14Synthesis of Biodiesel Fuel
Condenser No Water Flow
Mixture of vegetable oil, Methyl Alcohol,
and Potassium Hydroxide
Blue Plastic Clamp
Water Bath 55oC
15Synthesis of Biodiesel Fuel
- Procedure (cont)
- Turn on the magnetic stirrer (Left knob on hot
plate)to the highest level possible that allows
the bar to spin smoothly - Stir for 30 minutes
- Transfer all of the liquid in the flask to a
15-mL centrifuge tube with a cap - Let the mixture sit for about 20 minutes
- Two layers should form
- The top layer is the biodiesel product
- The lower layer is mainly glycerol
- Using a plastic pipet, carefully remove the top
layer and transfer product to a pre-weighed 50-mL
beaker - (leave a little product behind with the bottom
layer to avoid contamination)
16Synthesis of Biodiesel Fuel
- Procedure (cont)
- Place the beaker on the hot plate and insert a
thermometer into the biodiesel, holding the
thermometer in place with a clamp - Heat the biodiesel to about 70oC for 15-20
minutes to remove all the Methyl Alcohol - Remove the beaker from the hot plate and allow it
to cool to room temperature - Weigh the beaker and obtain the mass of biodiesel
produced - Record the appearance of the biodiesel
- Obtain an IR spectrum
- CAS No. for diesel fuel 68476-34-6