The document summarizes various processes for biodiesel production, with a focus on transesterification. It describes four main methods - pyrolysis, micro-emulsification, dilution, and transesterification. Transesterification, which is the reaction of triglycerides with alcohol in the presence of an acid or base catalyst, is identified as the most common industrial process. The key steps of transesterification including catalyst selection, reaction conditions, and separation of biodiesel and glycerol are outlined. Post-production processes like refining, washing, drying and additive treatment are also summarized to purify the biodiesel and meet fuel standards.

1. BIODIESEL PRODUCTION
PROCESSES
Dr. Ajay Singh Lodhi
Assistant Professor
College of Agriculture, Balaghat
Jawahar Lal Krishi Vishwa Vidyalaya, Jabalpur (M.P.)

2. METHOD OF BIODIESEL PRODUCTION
 An adaptation of the vegetable oil as a Compression
Ignition (CI) engines fuel can be done by four methods
 Pyrolysis;
 Micro-emulsification;
 Dilution; and
 Transesterification.

3. PYROLYSIS
 The pyrolysis refers to a chemical change caused by
the application of thermal energy in the absence of air
or nitrogen. The liquid fractions of the thermally
decomposed vegetable oils are likely to approach diesel
fuels.
 The pyrolyzate has a lower viscosity, flash point, and
pour point than diesel fuel and equivalent calorific
values. The cetane number of the pyrolyzate is lower.
 The pyrolyzed vegetable oils contain acceptable
amounts of sulfur, water and sediments and give
acceptable copper corrosion values but unacceptable
ash, carbon residual and pour point.

4. MICRO-EMULSIFICATION
 The formation of micro emulsion is one of the potential
solutions for solving the problem of vegetable oil
viscosity.
 Micro-emulsions are defined as transparent,
thermodynamically stable colloidal dispersion.
 The droplet diameters in micro-emulsions range from
100 to 1000 Å. Microemulsion can be made of vegetable
oils with an ester and dispersant (co solvent), or of
vegetable oils, and alcohol and a surfactant and a
cetane improver, with or without diesel fuels. All
micro-emulsions with butanol, hexanol and octanol met
the maximum viscosity requirement for diesel fuel.
 The 2-octanol was found to be an effective amphiphile
in the micellar solubilization of methanol in triolein
and soybean oil.

5. DILUTION
 The dilution of vegetable oils can be accomplished with
such material as diesel fuels, solvent or ethanol.
 Dilution results in the reduction of viscosity and density
of vegetable oils. The addition of 4% ethanol to diesel
fuel increases the brake thermal efficiency, brake torque
and brake power, while decreasing the brake specific
fuel consumption.
 Since the boiling point of ethanol is less than that of
diesel fuel, it could assist the development of the
combustion process through an unburned blend spray.

6. TRANSESTERIFICATION
 Transesterification is the method of biodiesel
production from oils and fats and can be carried out by
two ways.
 (a) Catalytic Transesterification.
 (b) Supercritical Methanol Transesterification
Catalytic Transesterification
 The “Catalytic Transesterification” process is the
reaction of a triglyceride (fat/oil) with an alcohol in the
presence of some catalyst to form esters and glycerol.
 A triglyceride has a glycerin molecule as its base with
three long chain fatty acids attached. The
characteristics of the oil/fat are determined by the
nature of the fatty acids attached to the glycerin. The
nature of the fatty acids can in turn affect the
characteristics of the biodiesel.

7. The products of the reaction of biodiesel
A successful transesterification reaction is signified by the
separations of the ester and glycerol layer after the
reaction time. The heavier, co-product, glycerol settles out
and may be sold as it is or it may be purified for use in
other industries, e.g. the pharmaceutical, cosmetics etc.

8. ACID CATALYZED TRANSESTERIFICATION
 The acid catalyzed process is the reaction of a
triglyceride (fat/oil) with an alcohol in the presence of
acid catalyst, preferably sulphonic and sulphuric acids
to form esters (biodiesel) and glycerol.
 These catalysts give very high yields in alkyl esters, but
the reactions are slow, requiring, typically,
temperatures above 100°C.
 The acid-catalyzed transesterification should be carried
out in the absence of water, in order to avoid the
competitive formation of carboxylic acids which reduce
the yields of alkyl esters.

9. ALKALINE CATALYZED TRANSESTERIFICATION
 The alkaline catalyzed transesterification process is the
reaction of a triglyceride (fat/oil) with an alcohol in the
presence of an alkaline catalyst such as alkaline metal
alkoxides and hydroxides as well as sodium or potassium
carbonates to form esters (biodiesel) and glycerol.
 The alkaline catalyzed transesterification of vegetable oil
proceeds faster than the acid catalyzed reaction. Due to this
reason, together with the fact that the alkaline catalysts are
less corrosive than acidic compounds, industrial processes
usually favor alkaline catalysts, such as alkaline metal
alkoxides and hydroxides as well as sodium or potassium
carbonates.
 But the presence of water and high amount of free acid gives
rise to saponification of oil and therefore, incomplete
reaction during the alkaline transesterification process with
subsequent formation of emulsion and difficulty in
separations of glycerol.

10. LIPASE CATALYZED TRANSESTERIFICATION
 The lipase catalyzed transesterification process is the
reaction of a triglyceride (fat/oil) with an alcohol in the
presence of lipase enzyme as a catalyst to form esters
(biodiesel) and glycerol.
 In lipase catalyzed process no complex operations are
needed not only for the recovery of glycerol but also in
the elimination of catalyst and soap.
 This is an environmentally more attractive option to
the conventional process. However, the reaction yields
as well as the reaction times are still unfavorable
compared to the alkaline catalyzed reaction systems.

11. SUPER CRITICAL TRANSESTERIFICATION
 The simple transesterification processes discussed above are
confronted with two problems, i.e. the processes are relatively
time consuming and needs separations of the catalyst and
saponified impurities from the biodiesel.
 The first problem is due to the phase separations of the
vegetable oil/ alcohol mixture, which may be dealt with by
vigorous stirring. These problems are not faced in the
supercritical method of transesterification.
 This is perhaps due to the fact that the tendency of two phase
formation of vegetable oil/alcohol mixture is not encountered
and a single phase is found due to decrease in the dielectric
constant of alcohol in the supercritical state (at 340°C and 43
MPa). As a result, the reaction was found to be complete in a
very short time within 2-4 mins.
 Further, since no catalyst is used, the purification of biodiesel
is much easier, trouble free and environment friendly
(Demirbas, 2005).

12. BIODIESEL PREPARATIOSNS BY CATALYTIC
TRANSESTERIFICATION METHOD
 Refined corn oil, palm oil, waste cooking cotton seed and rice
bran oils were esterified by the transesterification method.
Transesterification is otherwise known as alcoholysis. It is
the reaction of fat or oil with alcohol to yield esters and
glycerin.
 Transesterification of selected oils was carried out by
heating the oil. In this process, alcohol combines with
triglyceride molecule from acid to form glycerol and ester.
The glycerol is then removed by density separations.
 Simple alcohols are used for transesterification and this
process is usually carried out with a basic catalyst (NaOH,
KOH) in the complete absence of water.
 Transesterification decreases the viscosity of oil, making it
similar to diesel fuel in characteristics. A catalyst is used to
improve the reaction rate and yield. Transesterification of
triglycerides using alcohol is shown in Figure.

13. Biodiesel production process by transesterification method

14.  The “catalytic
transesterification” process
is the reaction of a
triglyceride (fat/oil) with an
alcohol in the presence of
acidic, alkaline or lipase as
catalyst to form mono alkyl
ester (i.e. Biodiesel) and
glycerol. Alkaline catalyzed
transesterification is the
fastest and require simple
setup Therefore, in current
the study, the SVO of
selected oils was
transesterified with methyl
alcohol in the presence of
strong alkaline sodium
hydroxide catalyst in a
batch type
transesterification reactor.
Schematic sketch of
transesterification reactor

15.  To prepare biodiesel from SVO of selected oils, first, the
sodium hydroxide is added to methyl alcohol to form sodium-
methoxide; simultaneously oil is heated in a separate vessel
to remove moisture.
 Moisture free oil is kept in the inner vessel of
transesterification reactor, and subjected to heat and stirring.
When the temperature of the oil reaches 60°C, then sodium
methoxide is mixed into the oil and the reaction mixture is
stirred for more than one hour until separation of glycerol is
started.
 Separation of glycerol is checked by taking a small sample of
reactant in a test tube. When separation of glycerol starts
then stirring is stopped and the reaction mixture is
transferred to a separate container.
 After 8 hours the reaction mixture is separated into the
methyl esters in the upper layer and the glycerol in the lower
layer. The methyl esters are decanted and washed three times
with warm distilled water to remove traces of soap and other
impurities. The final product obtained is good quality
biodiesel.

16. Bio-Diesel Production
(TNAU biodiesel pilot plant)
 For the esterification of Jatropha oil, alkaline-based
catalyst is used in this plant.
 The Jatropha oil is blended with alcohol and catalyst
mixture.
 The oil extracted from the seeds of Jatropha is mixed
with methanol catalyst mixture at a proportion under a
particular temperature.
 This solution is continuously stirred for two hours.
 During the above process, glycerol present in the
solution separate out, which when settled can be
separated out. For settling, three separate tanks are
provided in the plant.
 After removing the glycerol, the liquid biodiesel is
transferred to washing tank, where the fuel is washed
twice and the purified biodiesel is obtained.

17. ➢By using the this
unit, about 250
litres of biodiesel
could be produced
in a day.
➢The cost of the
unit is approx 1.5
lakhs.
➢This could be
reduced by
appropriate
substitutions in
the existing plant.
Depending upon
the need, the size
of the unit can be
scaled up to get
higher capacity.

19. Mechanics of the transesterification process
 Take 50 litres of Jatropha oil in the container and pump oil from inlet
tank to biodiesel reactor by using inlet pump (10 minutes)
 Switch ON for heater of biodiesel reactor
 Take 20 per cent of methanol and 1 per cent of sodium hydroxide (by
weight of oil) in the chemical mixing tank. Ensure that gate valve for
chemical tank is in closed position before filling of methanol into tank
 Switch ON for stirrer of chemical mixing tank (15 minutes) to produce
the sodium methoxide solution
 After reaching reaction temperature 60 deg. C, the sodium methoxide is
send to biodiesel reactor by opening of gate valve and close the valve.
 Switch ON for main stirrer of biodiesel reactor and reaction is continued
for about 2 hours
 After reaction time is completed, open the gate valve for glycerol settling
tank and the biodiesel and glycerol mixer is send to the glycerol settling
tank (by using storage switch)
 Allow the biodiesel mixture in glycerol settling tanks for 12 hours
 Before feeding of raw biodiesel, fill 100 litres of water in the washing
tank
 Remove the glycerol from settling tank and biodiesel is sent to washing
tank by opening gate
 Switch ON the aerator for 30 minutes. Allow the sample for 3 hours and
remove the biodiesel from washing tank
 Heat the biodiesel for 20 minutes to remove the moisture.

20. POST PRODUCTION PROCESS
Refining (Cleaning)
 The esters recovered from the reaction mixture are
refined to meet the requirements of ASTM D 6751-2. The
topics include: biodiesel/glycerol separation, ester
washing, ester drying, other ester treatments and
additization.
Biodiesel/glycerol separation
 The biodiesel /glycerol separation is typically the first
step of product recovery in most biodiesel processes.
 The separation process is based on the facts that fatty
acid alcohol esters and glycerol are sparingly mutually
soluble, and that there is a significant difference in
density between the ester and glycerol phases. The
presence of methanol in one or both phases affects the
solubility of ester in glycerol and glycerol in ester.

21.  The biodiesel washing step is used to neutralize any residual
catalyst, to remove any soaps formed during the esterification
reaction and to remove residual free glycerol and methanol.
 Ester drying is required to meet the stringent limits on the
amount of water present in the final biodiesel product. In
addition, there may be other treatments used to reduce color
bodies in the fuel, remove sulfur and phosphorus from the
fuel, or to remove glycerides.
 Additization is the addition of materials that have a specific
functionality that modifies one or more fuel properties.
Examples include cloud point/pour point additives,
antioxidants, or other stability enhancing agents.
 Fatty acid alcohol esters have a density of about 0.88 gm/cc,
while the glycerol phase has a density on the order of 1.05
gm/cc, or more. The glycerol density depends on the amount of
methanol, water, and catalyst in the glycerol. This density
difference is sufficient for the use of simple gravity separation
techniques for two phases.
 Any of the three categories of the equipments viz., Decanter
system or Centrifuge System or Hydro cyclone can be used to
separate the ester and glycerol phases.

22. Thank You