What is biodiesel?

  “Biodiesel is the name of a clean burning alternative fuel, produced from domestic, renewable resources. Biodiesel contains no petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with little or no modifications. Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics.”

http://www.biodiesel.org/what-is-biodiesel/biodiesel-faq's (accessed 21 Jan. 2013)

What is biodiesel?   “For entities seeking to adopt a definition of biodiesel for

purposes such as federal or state statute, state or national divisions of weights and measures, or for any other purpose, the official definition consistent with other federal and state laws and Original Equipment Manufacturer (OEM) guidelines is as follows:

Biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats which conform to ASTM D6751 specifications for use in diesel engines. Biodiesel refers to the pure fuel before blending with diesel fuel. Biodiesel blends are denoted as, "BXX" with "XX" representing the percentage of biodiesel contained in the blend (ie: B20 is 20% biodiesel, 80% petroleum diesel).”

http://www.biodiesel.org/what-is-biodiesel/biodiesel-faq's (accessed 21 Jan. 2013)

The chemistry . . .   vegetable oils are triglycerides obtained from plant materials

that are liquid at room temperature (triglycerides that are solid at room temperature are fats – whether derived from animal or plants)   Triglycerides = 3 fatty acids joined to a glycerin (glycerol) backbone

The chemistry . . .   mono-alkyl esters of long chain fatty acids, are produced

through a transesterification reaction

  the reaction uses an alcohol and produces one glycerin and three fatty acid esters for each triglyceride molecule that reacts completely

  when methanol is used as the esters are called fatty acid methyl esters (FAMEs)

  the reaction we are using is alkali-catalyzed

The chemistry . . .

R1, R2, and R3 may be different

H

H

H

H

O

O

O

H3 C

OH3 C

O

OH3 C

O

H

H

H

H

H

H

H

H

H

H

O

O

OH

H

H

O

O

H3 C

CH3

OH3 C

O

CH3

OH3 C

OCH3

+

+

KOH, heat

+ 3

Synthetic Procedure & Work-up   Filter used oil to remove unwanted solid (food

waste) as necessary   combine 50 mL of oil, as described below, with

excess (10 mL) methanol (CH3OH) and sufficient NaOH or KOH (about 4 to 5 mmole)   NaOH is dissolved in excess CH3OH (may require

gentle heating). Do not overheat to avoid loss of CH3OH. Slowly add the sodium methoxide (CH3OH + NaOH) solution to the oil with stirring.

  stir the reaction mixture, with no heat, for 30 min. (mix the methoxide solution with the oil).

Synthetic Procedure & Work-up   remove reaction from stirrer and allow to sit

(in a separatory funnel) until the glycerol has settled to the bottom (~30minutes). The top liquid is the biodiesel.   collect both layers (and determine the volume and

density of each).   the biodiesel may be washed with water, or

better yet, with 0.15 M acetic acid.   separate the biodiesel from the wash solution

and dry it over MgSO4.

Prelab calculations

Separatory funnel use

http://www.chem-ilp.net/labTechniques/SolventExtraction.htm (13 Jan. 2013)

Extraction ≠ washing (but technique is comparable)

Drying biodiesel

  An anhydrous salt, such as MgSO4, Na2SO4, of CaCl2 can be added

  H2O is attracted to dry ionic solids

http://www.chem-ilp.net/labTechniques/DryingLiquids.htm (21 Jan. 2013)

week 2 of biodiesel . . .

  Viscosity determination   Characterization of reactants

  IR   NMR   GC-MS

  Next week in pre-lab lecture / discussion we will discuss these topics