Biodiesel Production: Terminology & Formulation

Barry Latham, M.A.Ed.Biodiesel Production & Curriculum

Chemistry & Physics InstructorChicago Heights, Illinois

Terminology

Biodiesel- fuel made from vegetable oils or animal fats◦Transesterification (vegetable oils)- the process

of exchanging an alkoxy group of an ester compound with another alcohol

◦Saponification (animal fats)- the hydrolysis of an ester under basic conditions to form an alcohol and the salt of the carboxylic acid

Alcohol- any carbon chain which includes an –OH group◦Methanol (MeOH) or Ethanol (EtOH)

TerminologyCatalyst- a substance that is used in a

chemical reaction, but not consumed◦Potassium Hydroxide (KOH)◦Sodium Hydroxide (NaOH)

FAME- Fatty Acid Methyl Esters (<1 g/mL)◦Biodiesel

B100- 100% biodieselB20- 20% biodiesel, 80% traditional diesel

Glycerin- co-product of biodiesel (~1.173 g/mL)◦Can be made into liquid (KOH) or bar (NaOH) soap

Catalyst Choice Potassium Hydroxide (KOH)

◦ Most used by homebrewers◦ Dissolves faster as flakes than NaOH pellets◦ Glycerin produced can be easily made into liquid soap

Sodium Hydroxide (NaOH)◦ Typically causes more complications with soap formation◦ Used more in the industry◦ Glycerin produced can be easily made into bar soap

Sodium Methacrylate (H2C=C(CH3)CONa)◦ More effective catalyst

All have a high pH (caustic) All are dangerous- can burn skin, eyes, respiratory system

Alcohol ChoiceMethanol (MeOH)

◦ Shortest-chain alcohol◦ Most used by both homebrewers and in the industry◦ Biological effects similar to consuming ethanol, but more

severe Can cause nervous system failure, blindness if ingested or

absorbed through the skin or breathed in great quantities

Ethanol (CH3CH2OH)◦ 2-carbon chain alcohol◦ More restrictions on purchasing, storage and use◦ Higher rate of complications in reaction◦ Can cause inebriation

Both highly flammable and must be respectedStore only as much as you need in a safe area

◦ Obey local fire codes

Safety Issues Methanol

◦ Flammable◦ Can be absorbed through the skin◦ Can cause blindness and death

Potassium Hydroxide◦ Burns◦ Do not allow to touch your skin

Personal Protection Equipment (PPE)◦ Operate in a well-ventilated area◦ Wear safety goggles◦ Protective gloves◦ Do not directly inhale any vapors◦ Tie lose hair back◦ Wear closed toe shoes and long pants

FAME Reaction“Fatty Acid Methyl Ester”

Incomplete Reactions

                        

                                  

                      

                                      

                      

                                         

monoglyceride(2/3 reaction)

diglyceride(1/3 reaction)

Triglyceride(no reaction)

16%BOOST Method100L, 16% MeOH, 2-Stage Process

Perform titration◦ Our oil titrates at 0.44 (August 28, 2008, 34 trials)◦ 0.45 (March 27, 2009, 5 trials)

Add 89% of KOH needed into 16L MeOH◦ Mix thoroughly (will mix overnight)

Add 14L of mixture to heated oil (55°C) Circulate for 1 hr. and settle overnight Add remaining KOH to remaining KOH/MeOH Drain glycerin and add remaining KOH/MeOH

mixture Circulate for 3 hr. and settle overnight Drain glycerin

80/20 Method100L, 18% MeOH, 2-Stage Process

Perform titration◦Our oil titrates at 0.44 (August 28, 2008,

34 trials)Add all KOH needed into 18L MeOH◦Mix thoroughly (will mix overnight)

Add 14.4L of mixture to heated oil (55°C)

Circulate for 1 hr. and settle overnight

Drain glycerin and add remaining KOH/MeOH mixture

Circulate for 3 hr. and settle overnight

Drain glycerin

22% Method100L, 22% MeOH, Single-Stage Process

Perform titration◦Our oil titrates at 0.44 (August 28, 2008, 34 trials)

Add all KOH needed into 22L MeOH◦Mix thoroughly (will mix overnight)

Add all of the mixture to heated oil (55°C)

Circulate for 3 hr. and settle overnight

Drain glycerin

“Dr. Pepper” Method (Small Scale)Single-Stage Process

Is typically used before a large batch

Results indicate how well the method will work on this specific oil

Must be done in the lab, not at oil collection site

Takes 12-24 hours for results

Performed in plastic pop bottle◦ MeOH will start to eat plastic

after 24-36 hours

Methods Summary

%MeOH needs to be at least 13%◦More MeOH ensure greater completion of

reaction◦Too much can be wasteful, though

Circulation times can vary◦1-3 hours per batch seems to work for most

Batch sizes of 100L used for simplicity in calculations (scaling up or down)

Glycerin Removal

Drain the bottom layer of glycerin

Dr. Pepper Method◦ Invert pop bottle and

gently squeeze while using your thumb as a valve

It is better to overflow and lose some biodiesel, than to leave some glycerin in your biodiesel

Biodiesel Use CautionsBiodiesel as an excellent solvent◦All natural rubber will eventually be dissolved

Use Viton, or other synthetic rubber hoses, seals and gaskets

◦Breaks down petroleum “grit” that builds up over time in the combustion chamber Grit is dissolved by biodiesel and can clog fuel and

exhaust filters

◦Starting with a lower % of biodiesel slows this process Can increase % over time while replacing rubber

material and filters