TRANSESTERIFICATION FOR BIOFUEL.

(R.COO)3.C3H5 + 3MeOH → 3 RCOOMe +

C3H8OH

In presence of catalyst and lots of water.

Interesterification

Interesterification involves an exchange of acyl group among triglycerides.

Acyl groups may exchange positions within a triglyceride or among triglyceride molecules.

Interesterification

Catalysts

• High temperature catalysts: KOH and NaOH

• Low temperature catalysts: Sodium Methoxide (NaOCH 3)

1. The formation of enolate ion

2. The formation of Beta-Keto ester

3. Interesterification

Reaction Mechanisms

Catalyst Function in Interesterification

Initial removal of an -proton by the base catalyst leads to the charge delocalized enolate anion.

CH3 C CH3

OOH

-

CH3 C CH2-

O

CH3 C CH2

O

+

C CH2CH3

O -

-

H2O +

Mechanism for Intramolecular Ester-Ester Interchange

O

O

C

COCH2R2

CH

O

R1

O COCH2R3

O

O

C

C

O COCH2R3

CH2R2O

O

C R1H

O

O-

O

C

COCH2R3

C

O

C CH2R2

H

R1

O

I II III

__

O

O

O

C

COCH2R3

C

O

C

H

CH2R2

O

R1

O

O

O

C

COCH2R3

C

O

C CH2R2

O

R1

H

__

III IV V

O

O

O

COCH2R2

C

COCH2R3

C

O

R1

H

_

Beta-Keto ester formation

Intraesterification

Enolate ion formation

Random Esterification

Interesterification can be carried out to an equilibrium condition, at which point the fatty acids assume an almost random distribution among triglycerides.

Intraesterification, Interesterification and Equilibrium Mixture.

O

L

O

L

S

O

S

L

L

O

S

S

Catalyst

Continued reaction

L

O

L

O

L

L

L

L

L

S

O

S

S

S

L

S

OO

S

S

S

S

LL

S

L

S

O

S

O

L

S

L

SS

O

O

O

O

O

LO

O

O

L

UUUSSS (SUS SSU) (SUU USU)

Interesterification can be directed away from its usually random end-point if the fat is allowed to crystallize during reactions.

The trisaturated glycerides crystallize first.

Direct Interesterification

Intraesterification, Interesterification and Equilibrium Mixture

O

L

O

L

S

O

S

L

L

O

S

S

Catalyst

Continued reaction

L

O

L

O

L

L

L

L

L

S

O

S

S

S

L

S

OO

S

S

S

S

LL

S

L

S

O

S

O

L

S

L

SS

O

O

O

O

O

LO

O

O

L

UUUSSS (SUS SSU) (SUU USU)

Directed Interesterification

S

O

L

1. Stearic-Stearic-Stearic 33.3 mole % solid2. Oleic-Oleic-Oleic 8.3 mole % liquid3. Linoleic-Linoleic-Linoleic 8.3 mole % liquid4. Oleic-Oleic-Linoleic 24.9 mole % liquid5. Oleic-Linoleic-Linoleic 24.9 mole % liquid

Applications

Shortenings: The proportion of palmitic acid in the 2-position is reduced from about 64% to 24% on random interesterification.

Natural lardRandomized lard

Randomization of lard improves its plastic range and thus makes it a better shortening than natural lard.

Plasticity and Consistency

Plasticity is the changes in consistency as a function of temperature.

Consistency is the apparent hardness at a temperature

Margarines – High Stability Margarine Blends

1. 75 % (co-randomized 40 % coconut oil / 60 % palm oil),

2. 10 % (co-randomized 50% coconut oil / 50 %

hydrogenated canola oil) and

3. 15 % hydrogenated soybean oil

Good spreadability, high temperature stability, and good eating qualities.

Nutritional Margarine Blends

High polyunsaturated content and low-to-zero

trans-acid containing margarines are produced by

interesterifying a blend of liquid oil and a fully

hydrogenated oil.

Confectionary Fats

Hydrogenated palm kernel oil is a hard butter melting at 46C and produces a waxy feel in the mouth.

On randomization, its melting point is reduced to 35C. By blending hydrogenated palm kernel oil and its randomized product, a whole series of hard butters with highly desirable melting qualities (rapid melt in mouth) are obtained

BLOCK DIAGRAM FOR KRAFT PROCESS

KRAFT PROCESS

Slaking &

Causticizing

Settling &

Filtration

Digester

Blow Tank

Recovery

Furnace

Dissolving

Tank

Lime Kiln

Mu

ltip

le E

ffect

Evap

ora

tors

Lime

Recovered White Liquor

Pulp to further

processing

GasesOff Gas

Wood Chips

SteamWeak

Black Liquor

Steam

Strong Black Liquor

Condensate

Flue Gas

Smelt

Off Gas

Water

Green Liquor

Calcium Carbonat

e

Air

Gases

Gaseous Waste

Washers

Reference: El-Halwagi, M. M., Reference: El-Halwagi, M. M., Pollution Prevention through Process Integration: Systematic Design Tools. Academic Press, 1997.. Academic Press, 1997.

Tier III – Problem Statement

Energy in the Kraft pulping processEnergy in the Kraft pulping process

The Kraft pulping process is a very energy-intensive process: electricity end-uses The Kraft pulping process is a very energy-intensive process: electricity end-uses common to all pulp and paper mills include pumping, air-handling, and lighting. In common to all pulp and paper mills include pumping, air-handling, and lighting. In addition, steam needs and the large number of process streams makes this sector addition, steam needs and the large number of process streams makes this sector of the industry a good candidate for improved heat integration. Black liquor of the industry a good candidate for improved heat integration. Black liquor concentration is usually the biggest single steam using operation in a Kraft pulp mill. concentration is usually the biggest single steam using operation in a Kraft pulp mill. Evaporators installed in the 1960s and 1970s were built with four or five effects, Evaporators installed in the 1960s and 1970s were built with four or five effects, whereas most Kraft mills today use five or six effect evaporators, with a whereas most Kraft mills today use five or six effect evaporators, with a concentrator to further increase solids content. Firing the recovery boiler with the concentrator to further increase solids content. Firing the recovery boiler with the black liquor at higher solids content improves overall boiler performance and is a black liquor at higher solids content improves overall boiler performance and is a general trend in the industry.general trend in the industry.

To counter this energy consumption problem, a Kraft pulp mill uses biomass. In fact, To counter this energy consumption problem, a Kraft pulp mill uses biomass. In fact, in addition to being the feedstock for pulp and paper production, biomass is also a in addition to being the feedstock for pulp and paper production, biomass is also a major energy resource for the industry. The industry also has access to residues of major energy resource for the industry. The industry also has access to residues of pulpwood harvesting, some of which can be removed from the forest on a pulpwood harvesting, some of which can be removed from the forest on a sustainable basis. All black liquor and most mill residues are used at mill sites to sustainable basis. All black liquor and most mill residues are used at mill sites to fuel cogeneration systems, providing steam and electricity for on-site use. fuel cogeneration systems, providing steam and electricity for on-site use. Cogeneration also known as Combined Heat and Power (CHP) is the simultaneous Cogeneration also known as Combined Heat and Power (CHP) is the simultaneous production of electricity and useful heat from the same fuel or energy. A typical production of electricity and useful heat from the same fuel or energy. A typical cogeneration system consists of an engine, steam turbine, or combustion turbine cogeneration system consists of an engine, steam turbine, or combustion turbine that drives an electrical generator. A waste heat exchanger recovers waste heat that drives an electrical generator. A waste heat exchanger recovers waste heat from the engine and/or exhaust gas to produce hot water or steam. from the engine and/or exhaust gas to produce hot water or steam.