Biodiesel production is the process of making biodiesel. Biodiesel is a liquid fuel source largely compatible with petroleum based diesel fuel. It is synthesized by replacing glycerol with a short chain alcohol such as methanol or ethanol in a step known as transesterification. Biodiesel refers to a diesel-equivalent, processed fuel derived from biological sources (such as vegetable oils), which can be used in unmodified diesel-engined vehicles. ... Pracsamp 07:34, 16 February 2007 (UTC)— Pumpjack pumping an oil well near Sarnia, Ontario Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Rudolf Christian Karl Diesel (1858-1913), inventor of the diesel engine. ... Methanol, also known as methyl alcohol, wood alcohol or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... Ethanol, also known as ethyl alcohol or grain alcohol, is a flammable, colorless, slightly toxic chemical compound with a distinctive perfume-like odor, and is the alcohol found in alcoholic beverages. ... In organic chemistry, transesterification is the process of exchanging the alkoxy group of an ester compound by another alcohol. ...

Transesterification chemistry

A reaction scheme is as follows:

Image File history File links Transesterification_of_triglycerides. ...

Animal and plant fats and oils are typically made of triglycerides which are esters of free fatty acids with the trihydric alcohol, glycerol. In the transesterification, the alcohol is deprotonated with a base to make it a stronger nucleophile. Commonly, ethanol or methanol is used. As can be seen, the reaction has no other inputs than the triglyceride and the alcohol. It has been suggested that Medium Chain Triglycerides be merged into this article or section. ... General formula of a carboxylate ester. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... Glycerol, also well known as glycerin and glycerine, and less commonly as propane-1,2,3-triol, 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. ... Deprotonation is a chemistry term that refers to the removal of a proton (hydrogen ion H+) from a molecule, forming the conjugate base. ... In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ...

Normally, this reaction will proceed either exceedingly slowly or not at all. Heat, as well as an acid or base are used to help the reaction proceed more quickly. It is important to note that the acid or base are not consumed by the transesterification reaction, thus they are not reactants but catalysts. An acid (often represented by the generic formula HA) is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a pH of less than 7. ... A base in chemistry is a chemical substance which has a free pair of electrons to bind a hydrogen ion commonly referred to as a proton (IUPAC definition). ... A reaction is the following: In physics, a reaction (physics) is defined by Newtons third law: For every action there is an equal and opposite reaction. The idea that any given force has a pair or opposite force. ...

Almost all biodiesel is produced using the base-catalyzed technique as it is the most economical process requiring only low temperatures and pressures and producing over 98% conversion yield (provided the starting oil is low in moisture and free fatty acids). For this reason only this process will be described below. Yield may mean: In economics, yield is a measure of the amount of income an investment generates over time (related to return on investment). ...

The following steps can be performed in a small, home-based biodiesel processor, or in large industrial facilities. The chemistry is similar in either case. A Biodiesel processor is a combination reaction vessel and still for producing biodiesel from vegetable oil. ...

Wikibooks has a book on the topic of

How to make biodiesel

Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ...

Steps in the process

The major steps required to synthesize biodiesel are as follows:

Purification

If waste vegetable oil is used, it is filtered to remove dirt, charred food, and other non-oil material often found. Waste Vegetable Oil (WVO) is vegetable oil that has become unfit for food preparation due to chemical degradation (oxidation, hydrogenation) and/or accumulation of contaminants. ...

Water is removed because its presence causes the triglycerides to hydrolyze to give salts of the fatty acids instead of undergoing transesterification to give biodiesel. Saponification is the hydrolysis of an ester under basic conditions to form an alcohol and the salt of the acid. ...

At home, this is often accomplished by heating the filtered oil to approximately 120°C. At this point, dissolved or suspended water will boil off. When the water boils, it spatters (chemists refer to it as "bumping"). To prevent injury, this operation should be done in a sufficiently large container (at most two thirds full) which is closed but not sealed.

In the laboratory, the crude oil may be stirred with a drying agent such as magnesium sulfate to remove the water in the form of water of crystallization. The drying agent can be separated by decanting or by filtration. However, the viscosity of the oil may not allow the drying agent to mix thoroughly. Water of crystallization is water that is tightly associated with crystalline metal salts, and remains after drying in a fixed proportion to the salt. ...

Neutralization of free fatty acids

A sample of the cleaned oil is titrated against a standard solution of base in order to determine the concentration of free fatty acids (RCOOH) present in the waste vegetable oil sample. The quantity (in moles) of base required to neutralize the acid is then calculated. Titration setup: the titrant drops from the burette into the analyte solution in the flask. ... A mole (symbol: mol) is approximately 6. ...

Transesterification

While adding the base, a slight excess is factored in to provide the catalyst for the transesterification.

The calculated quantity of base (usually sodium hydroxide) is added slowly to the alcohol and it is stirred until it dissolves. Sufficient alcohol is added to make up three full equivalents of the triglyceride, and an excess is added to drive the reaction to completion. Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic metallic base. ...

The solution of sodium hydroxide in the alcohol is then added to a warm solution of the waste oil, and the mixture is heated (typically 50 °C) for several hours (4 to 8 typically) to allow the transesterification to proceed. A condenser may be used to prevent the evaporative losses of the alcohol. Care must be taken not to create a closed system which can explode. Diagram of typical reflux apparatus. ...

Workup

Once the reaction is complete, the glycerol should sink. When ethanol is used, it is reported that an emulsion often forms ^{[citation needed]}. This emulsion can be broken by standing, centrifugation, or the addition of a low boiling (easily removed) nonpolar solvent, decanting, and distilling ^{[citation needed]}.

The top layer, a mixture of biodiesel and alcohol, is decanted. The excess alcohol can be distilled off, or it can be extracted with water. If the latter, the biodiesel should be dried by distillation or with a drying agent.

Reaction

The reaction may be shown

CH₂COOR1
|
CHCOOR1 + 3 CH₃OH → (CH₂OH)₂CH-OH + 3 CH₃COO-R1
|
CH₂COOR1

Since we are dealing with nature, the alkyl group on the triglycerides is probably different, so it would actually be more like

CH₂OC=OR1
|
CHOC=OR2 + 3 CH₃OH → (CH₂OH)₂CH-OH + CH₃COO-R1 + CH₃COO-R2 + CH₃OC=O-R1
|
CH₂COOR3

Triglyceride + methanol → Glycerol + Esters

R1, R2, R3 : Alkyl group. It has been suggested that Medium Chain Triglycerides be merged into this article or section. ... Methanol, also known as methyl alcohol, wood alcohol or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ... An alkyl is a univalent radical containing only carbon and hydrogen atoms arranged in a chain. ... In organic chemistry, functional groups are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ...

During the esterification process, the triglyceride is reacted with alcohol in the presence of a catalyst, usually a strong alkaline (NaOH, KOH or sodium silicate). The main reason for doing a titration to produce biodiesel, is to find out how much alkaline is needed to ensure a complete transesterfication. Empirically 6.25 g / L NaOH produces a very usable fuel. One uses about 6 g NaOH when the WVO is light in colour and about 7 g NaOH when it is dark in colour. The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic metallic base. ... The chemical compound potassium hydroxide, (KOH) sometimes known as caustic potash, potassa, potash lye, and potassium hydrate, is a metallic base. ... Sodium silicate, also known as water glass, is a compound used in cements and textile processing. ... Titration setup: the titrant drops from the burette into the analyte solution in the flask. ... BIC pen cap, about 1 gram. ... The litre or liter (U.S. spelling, see spelling differences) is a unit of volume. ... Waste Vegetable Oil (WVO) is vegetable oil that has become unfit for food preparation due to chemical degradation (oxidation, hydrogenation) and/or accumulation of contaminants. ...

The alcohol reacts with the fatty acids to form the mono-alkyl ester (or biodiesel) and crude glycerol. The reaction between the biolipid (fat or oil) and the alcohol is a reversible reaction so the alcohol must be added in excess to drive the reaction towards the right and ensure complete conversion. A reversible reaction is a chemical reaction that may proceed in both the forward and reverse directions. ...

Base catalysed mechanism

This reaction is base catalysed. Any strong base will do, e.g. NaOH, KOH, Sodium Methoxide, etc. Commonly the base (KOH,NaOH) is dissolved in the alcohol to make a convenient method of dispersing the otherwise solid catalyst into the oil. The ROH needs to be very dry. Any water in the process promotes the saponification reaction and inhibits the transesterification reaction.

A word on methoxide production: Claims that methoxide is produced by the reaction Methoxide is an organic salt, in pure form a white powder. ...

KOH + ROH → RO^- + H₂O

are incorrect as the reaction constant is on the order of K_log -15. I.e. the reaction equilibrium is far to the left. While KOH and NaOH are strong bases, methoxide can only be produced by reacting e.g. sodium metal in alcohol. However, the following reaction mechanism using methoxide as an example are common in the literature as methoxide is an excellent base catalyst for this reaction.

Once the alcohol mixture is made, it is added to the triglyceride. The S_n2 reaction that follows replaces the alkyl group on the tricglyceride in a series of reactions.

The carbon on the ester of the triglyceride has a slight positive charge, and the oxygens have a slight negative charge, most of which is located on the oxygen in the double bond. This charge is what attracts the RO^- to the reaction site

 R1 Polarized Attraction | RO- ————————————————> C=O | O-CH2-CH-CH2-O-C=O | | O-C=O R3 | R2 

This yields a transition state that has a pair of electrons from the C=O bond now located on the oxygen that was in the C=O bond.

 R1 | RO-C-O- (pair of electrons) | O-CH2-CH-CH2-O-C=O | | O-C=O R3 | R2 

These electrons then fall back to the carbon and push off the glycol forming the ester.

 R1 | RO-C=O + -O-CH2-CH-CH2-O-C=O | | O-C=O R3 | R2 

Then two more RO groups react via this mechanism at the other two C=O groups. This type of reaction has several limiting factors. RO^- has to fit in the space where there is a slight positive charge on the C=O. So MeO- works well because it is small. As the R on RO- gets bigger, reaction rates decrease. This effect is called steric hindrance. That is why methanol and ethanol are typically used.

There are several competing reactions, so care must be taken to ensure the desired reaction pathway occurs. Most methods do this by using an excess of RO^-.

The acid catalysed method is a slight variant, that is also affected by steric hindrance.

Process

• Preparation: care must be taken to monitor the amount of water and free fatty acids in the incoming biolipid (oil or fat). If the free fatty acid level or water level is too high it may cause problems with soap formation (saponification) and the separation of the glycerin by-product downstream.

• Catalyst is dissolved in the alcohol using a standard agitator or mixer.

• The alcohol/catalyst mix is then charged into a closed reaction vessel and the biolipid (vegetable or animal oil or fat) is added. The system from here on is totally closed to the atmosphere to prevent the loss of alcohol.

The reaction mix is kept just above the boiling point of the alcohol (around 70 °C, 158°F) to speed up the reaction though some systems recommend the reaction take place anywhere from room temperature to 55 °C (131°F) for safety reasons. Recommended reaction time varies from 1 to 8 hours; under normal conditions the reaction rate will double with every 10 °C increase in reaction temperature. Excess alcohol is normally used to ensure total conversion of the fat or oil to its esters.

• The glycerin phase is much more dense than biodiesel phase and the two can be gravity separated with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge is used to separate the two materials faster.

• Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by distillation. In other systems, the alcohol is removed and the mixture neutralized before the glycerin and esters have been separated. In either case, the alcohol is recovered using distillation equipment and is re-used. Care must be taken to ensure no water accumulates in the recovered alcohol stream.

• The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerin (water and alcohol are removed later, chiefly using evaporation, to produce 80-88% pure glycerin).

• Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage.

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ... Saponification is the hydrolysis of an ester under basic conditions to form an alcohol and the salt of the acid. ... Vessel can refer to any of the following: Objects Vessel (French vaissel, from a rare Latin vascellum, diminuitive of vas, vase, or urn), a word of somewhat wide application for many objects, the meaning common to them being capacity to hold or contain something. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... Room temperature describes a certain temperature within enclosed space that is uses for various purposes by human beings. ... ... Settling is the process by which particulates settle to the bottom of a liquid and form a sediment. ... Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures. ... The flash (or partial) evaporation is one of the simplest unit operations. ... Laboratory distillation set-up using, without a fractionating column 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed... This article or section is in need of attention from an expert on the subject. ...

Alternate production methods

Supercritical fluid methanol A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... Methanol, also known as methyl alcohol, wood alcohol or wood spirits, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odor that is somewhat milder and sweeter than ethanol (ethyl alcohol). ...

[1](pdf)

[2](pdf)biodiesel production without a catalyst

[3] 2 step method with hydrolysis followed by esterification with supercritical methanol(pdf)

Ultrasonic reactor

Using an ultrasonic reactor for biodiesel production drastically reduces your reaction times. Hence the process of transesterification can run inline rather than using the time consuming batch processing. Industrial scale ultrasonic devices allow for the industrial scale processing of several thousand barrel per day.

Ultrasonication benefits

• Reduction of reaction time by up to 97.5%

5–10 h(using conventional agitation)
15 min(using ultrasound irradiation)

• Reduction of static separation time by up to 98%

5–10 h(using conventional agitation)
10 min(using ultrasound irradiation)

• Increase of biodiesel yield to up to 99%

see Base Catalyzed Fast-Transesterification for details

• Reduction of catalyst requirement by up to 66%

Ultrasonication costs

Processing Costs

• approx. 0.2ct to 1.5ct per liter (0.8ct to 6.0ct/gallon) when used in commercial scale.

Ultrasonication links

• Ultrasonic Transesterification of Oil to Biodiesel in Industrial Scale (www.hielscher.com)

• Fast-Transesterification of Soybean Oil Using Ultrasonication

• Sonochemistry in Transesterification of Biodiesel

• www.chemistry.org ultrasonic irradiation

• www.biodys.com Ultrasonic reactor

• www.nrel.gov Biodiesel Production Technology (pdf)

See also

• Biodiesel
• Biodiesel processor
• Soap
• Transesterification
• WVO(waste vegetable oil)

Biodiesel refers to a diesel-equivalent, processed fuel derived from biological sources (such as vegetable oils), which can be used in unmodified diesel-engined vehicles. ... A Biodiesel processor is a combination reaction vessel and still for producing biodiesel from vegetable oil. ... Handmade soap Soap is a surfactant used in conjunction with water for washing and cleaning. ... In organic chemistry, transesterification is the process of exchanging the alkoxy group of an ester compound by another alcohol. ... Waste Vegetable Oil (WVO) is vegetable oil that has become unfit for food preparation due to chemical degradation (oxidation, hydrogenation) and/or accumulation of contaminants. ...

Academic reviews

• Carlson, Kimberly Sue, AH4U, 2004
• Gerpen, J.V., Biodiesel processing and production, Fuel Processing Technology, 2005, 86, 1097-1107. doi:10.1016/j.fuproc.2004.11.005
• Ma, F. & Hanna, M.A., Biodiesel production: a review, Bioresource Technology, 1999, 70, 1-15. doi:10.1016/S0960-8524(99)00025-5