BIODIESEL December 2015

Biodiesel What…. Why…….. How………. What…. Why…….. How……….

What is biodiesel ? Diesel oil made of vegetable oil. It has comparable properties with a “fossil diesel oil” Why use biodiesel ? To reduce the consumption of fossil diesel. To use renewable sources. How to prepare biodiesel ? Esterification

Biodesel is made from : waste vegetable oil (WVO) or straight vegetable oil (SVO). Lipid from algae Oil is Fatty acid. (Long chain Carboxylic Acid) What is oil? Cant we just use oil directly without converting into biodesel? Raw materials

Straight vegetable oils (SVO): - Too viscous - -Low cetane number -High freezing point (easy to freeze) Viscosity At 40 C: Petrodiesel :4 to 5 mm2/s, vegetable oils:30 and 40 mm2/s.

Cetane number is a measure of how quickly a fuel will ignite in a compression ignition engine. Cetane is very quickly ignited, and its number is set to 100. The cetane number of the fuel should be above 41. Most vegetable oils have an adequate cetane number, but, if necessary, additives can be mixed with the oil. Small amounts of acetone have been used. Cetane number (C 16 H 34 ), also called hexadecane,

Viscocity and Cetane Number

Freezing Point of Veg Oil corn oil - 20 deg. C sunflower oil - 17 deg. C olive oil - 6 deg. C sesame oil - 6 deg. C peanut oil 3 deg. C palm oil 24.1 deg. C coconut oil 25.1 deg. C What to do ?????

Solutions : a. Blend with Diesel oil or kerosene. b. Preheat (65 C) c. Transesterification --> biodiesel

Oil = Fatty Acid

Oil content (wt%) of oil fruits and oil seeds

ESTERIFICATION

Transesterification of triglycerides with alcohol Transesterification

CH 2 | CH | CH 2 CH 3 OCOR” OCOR”’ OCOR’ OH CH 3 OH

Transesterification of rapeseed oil using Transesterification of rapeseed oil

Flow diagram of the Jatropha Energy System

For biodiesel, methanol is currently popular, But ethanol is the better choice because it is Produced from biomass For biodiesel, methanol is currently popular, But ethanol is the better choice because it is Produced from biomass Methanol is usually obtained from petroleum although it can be produced from biomass. Methanol is toxic Methanol or ethanol ?

C 16 H 32 O 2 Molar mass g/mol You have 1000 kg of a vegetable oil that happens to consist of a single triglyceride (not a mixture of triglycerides). The three acids in each molecule are all palmitic acid (C16:0). What is the proper chemical name of this triglyceride? What is the molecular mass of the triglyceride? Estimate the number of kilograms of glycerine produced when the above vegetable oil is transesterified with ethanol.

Glycerol C 3H5(OH)3 Molar mass g/mol Molecular formula C16H32O2 Molar mass 256 When make a bond, loss 1 H → 255 Tri → 255 x 3 = 765 CH2-CH-CH2 = 41 Total = 806 This is a triple palmitate of glycerine hence it is glyceryl tri-palmitate.

Each mole of triglyceride releases 1 mole of glycerine upon being esterified kg of oil correspond to 1000/806 = 1.24 kilomoles. Hence glycerine produced : 1.24 kilomoles Weight of glycerine produced : 1.24 × 92 = 114 kg.

Example 2: To produce biodiesel, ethyl or methyl esters from rapeseed oil, ethanol or methanol, and potassium hydroxide are used in the reaction: a.Determine the theoretical conversion efficiency of the biodiesel reaction b. Determine the amount of ethanol required to convert 1 L of rapeseed oil reacted with 1 percent potassium hydroxide. Base your calculations on triolein since this is often the predominant triglyceride in vegetable-based oils: C57H98O6,

C57H98O6, MW 878 g/gmol, density 0.88 kg/L Ethanol: C2H5OH, MW: 46 g/mol, density kg/L Methanol: CH3OH, MW: 32 g/mol, density: kg/L Potassium hydroxide in alcohol (1 wt %/vol): Oleic acid 18:1 cis-9 C18H34O2 FuelDensity (kg/L) Energy (MJ/L) Biodiesel Methanol

CH2-CH-CH2 = 41 3 Oxygen = 3 X 16 = 48 3 Carbonyl (CO) = 3 x 28 = 84 3 oleic = 3 [( 17x12 )+(33 x 1)] = 3[ 237]= 711 Total = = 884 Molecular formula C 57 H 104 O 6 57* *16 = 884 Molecular weight

C 3 H 5 OOCR) C 2 H 5 OH → 3 RCOOC 2 H 5 + C 3 H 5 (OH) R= C 17 H 33 --> (17) ( )3 a. Conversion efficiency : 105 % 1000 gram = 1.13 mol 3 x 1.13 =3.39 mol =1050 gram b. The weight of 1 litre oil = volume x density, >0.88 kg = mol > ethanol = 3 x 0.99 mol = 3 mol = 3 x 46 gram = 138 gram Every 1 litre ( or 880 gram) oil needs 138 gram ethanol. Every 1 gram of ethanol will convert 880/138 = 6.4 gram 0f oil

b. Molar ratio for alcohol to triglyceride molecule is 3 to 1; → 3 mol EtOH × 46 g/mol = 138 g So 138 g of ethanol per gmol of triglyceride are needed. 1 gmol of triolean × 878 g/gmol = 878 g triolean; EtOH needed for compl conversion = 878 g triolean/138 g EtOH = 6.4 g oil/1 g

If methanol is used instead of ethanol : a.Stoichiometrically, how many kg of methanol are required for each kg of vegetable oil? b. If the methanol, were used directly as fuel, how much energy would be released? c. If 1 liter of biodiesel is used as fuel, how much energy is released? d. What is the methanol-to-biodiesel enegy ratio ? FuelDensity (kg/L) Energy (MJ/L) Biodiesel Methanol

C3H5(OOCR)3 + 3 CH3OH → 3 RCOOCH3 + C3H5(OH)3 a. 1 litre oil = 0.88 kg = mol > Methanol = 3 x 0.99 mol = 3 mol = 3 x 32 gram = 96 gram Every 1 litre ( or 880 gram) oil needs 96 gram Methanol. Every 1 gram of Methanol will convert 880/96 = 9.16 gram 0f oil (compare with that of ethanol) b. ref to table in question, methanol energy = 22.7 MJ / L Methanol density = 0.8 kg/L. Every 1 L methanol will produce 22.7 MJ energy Or, every 0.8 kg ( 800 gr) methanol will produce 22.7 MJ energy For every 96 gr methanol – > 96/800 x 22.7 = 2.72 MJ

C3H5(OOCR)3 + 3 CH3OH → 3 RCOOCH3 + C3H5(OH)3 c. Mw biodiesel = = mol oil will produce 3 mol biodesel. 3 mol biodesel= 3 x 296 gr = 888 gr ref to table, biodiesel energy = 36.6 MJ / L Biodiesel density = 0.88 kg/L. Every 1 L methanol will produce 36.6 MJ energy Or, every 0.88 kg ( 880 gr) methanol will produce 36.6 MJ energy For every 888 gr biodiesel – > 888/880 x 36.6 = 37 MJ FuelDensity (kg/L) Energy (MJ/L) Biodiesel Methanol

What is the main reason to prefer biodiesel to straight vegetable oils (SVO) as fuel for diesel engines? What should you do to make SVOs more acceptable as diesel fuel (other than making biodiesel out of them)?