ESTERIFICATION OF BIODIESEL Dr. K. SIVAKUMAR Department of Chemistry SCSVMV University 1

 Aim  Principle  Reaction  Chemicals required  Apparatus required  Procedure  References 2

Aim: Base (NaOH) catalyzed esterification of Biodiesel [Fatty acids Triglyceride carboxylic acids] using Methanol (CH 3 OH). Principle: Carboxylic acids contain the carboxyl group on carbon. In ester, the hydrogen in the carboxyl group replaced by an alkyl group. CH 3 COOHCH 3 COOR Esterification: Conversion of Carboxylic acids [CH 3 COOH] to Ester [CH 3 COOCH 3 ] by the treatment with alcohol[CH 3 OH]. 3

Reaction: Base catalyst 4

Chemicals required: Vegetable Oil (Edible / Non-edible) eg:- Neem Oil Soyabean Oil Jatropha Oil Palm Oil Alcohol - Methanol (CH 3 OH) / Ethanol (CH 3 CH 2 OH) Alkali - Sodiumhydroxide (NaOH) / Pot. hydroxide (KOH) 5

Apparatus required: Mechanical stirrer Heating mantle Round bottom flask Thermometer Condenser Separating funnel Measuring jars Beakers Funnels 6

Procedure: Step 1: Activation of alcohol: Sodium Hydroxide is dissolved in alcohol by vigorous stirring to form alkoxide in a closed vessel NaOH + CH 3 OH CH 3 ONa + H 2 O Sod. Hydroxide Methanol Sodium alkoxide 7

Step 2: TRANSESTERIFICATION / Alcoholysis Alcohol catalyst mixture is mixed with Oil Oil & Methanol ratio 10:1 by weight] Reaction mixture is heated for 70 o C for 3 hours to speed up the esterification process CH 2 −OCOR 1 R 1 COOCH 3 CH 2 − OH | CH- OCOR 2 + 3CH 3 OH R 2 COOCH 3 + CH − OH | CH 2 −OCOR 3 R 3 COOCH 3 CH 2 − OH Triglyceride Methanol Biodiesel Glycerol Alkaline catalyst 8

Side reaction: SAPONIFICATION R 4 COOH + NaOH R 4 COONa + H 2 O Free Fatty acid Base Soap Alkaline catalyst Step 3: Separation of alcohol: Methyl ester (BIODIESEL) and Glycerol are allowed to settle by gravity in a separating funnel The denser glycerol settle down, while the Biodiesel forms the upper layers. The two layers are separated Both layer contains equal amount of Methanol that has to be removed 9

Step 4: Methyl ester wash: Methyl ester (BIODIESEL) contains unused catalyst and Methanol To remove this, Methyl ester is neutralized with H 2 SO 4 (30%) to deactivate the catalyst Then, washed with hot water to remove the catalyst and washing is continued until the pH of washed water is in the range of 6 – 7 Washed ester is dried using silica gel Methanol can be removed by distillation 10

Biodiesel (Non-Edible Oil): BEFORE Esterification Biodiesel (Non-Edible Oil): AFTER Esterification 11

References & Tutorials:

? 13 Dr. K. SIVAKUMAR Department of Chemistry SCSVMV University