Basic Chemistry of Biodiesel Production p resented at CCURI Biofuels Workshop

1. Basic Chemistry of Biodiesel Production presented at CCURI Biofuels Workshop Muskegon Community College Muskegon, MI October, 17 – 20, 2013 by Chuck Crabtree Director – Iowa BioDevelopment Indian Hills Community College Ottumwa, IA

2. Topics What are the different types of oils? What are tryglicerides? Fatty acid structure. What are fatty acid profiles? What is esterification and transesterification? How does the fatty acid profile of the feedstock affect biodiesel performance? What are some of the more common feedstocks used for biodiesel production?

3. Introduction to Organic Oil Chemistry What is oil? • Three basic types: • Essential oils – Perfumes from plants • Mineral oils – Crude oil from petroleum • Organic oils – Animal and vegetable oils, soybean oil • – Are mixtures of hydrocarbons • – Are mixtures of triglycerides • Organic compound • Made up of carbon, hydrogen, and oxygen

4. Introduction to Organic Oil Chemistry Different Types of Oils – Essential Oil • Essential oils • A volatile oil (vaporizes at room temperature) • Has a characteristic odor or flavor • Generally obtained from a plant • Used to make perfumes and flavorings

5. Introduction to Organic Oil Chemistry Different Types of Oils – Petroleum • Crude oil or petroleum • No oxygen in structure • Only carbon and hydrogen • Mineral oil • Comes from the Earth • Is a mixture of a very large number of different hydrocarbons • Refined into a variety of hydrocarbons • Is a liquid by-product of the distillation of petroleum • Includes lubricating base oils such as motor oil

6. Introduction to Organic Oil Chemistry Characteristics of an Oil • Not soluble in water • Soluble in organic substances like methanol • Liquid at room temperature • Fat and grease similar but solid at room temperature

7. Introduction to Organic Oil Chemistry Different Types of Oils – Organic • Organic oils • Canola (Rapeseed) • Coconut • Corn oil • Flaxseed • Jatropha • Palm oil • Soybean oil • Sunflower oil • Waste vegetable oil (WVO) • Animal fats • Tallow – Usually cattle, sheep, or horse fat • Lard – Usually hog fat

8. Biodiesel Molecular Structure Parts of Biodiesel Molecule H H C H C H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H

9. Biodiesel Molecular Structure • Methyl group Parts of Biodiesel Molecule H H • Methyl Group C H C H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H

10. Biodiesel Molecular Structure • Methyl group • Fatty acid Parts of Biodiesel Molecule H H • Methyl Group C H C H C H H C H H C H H C • Fatty Acid H H C H H C H H C H H C H H C H H C H H

11. Biodiesel Molecular Structure • Parts of Biodiesel Molecule • Methyl group • Fatty acid • Have this structure • Most naturally occurring organic oils are esters Parts of Biodiesel Molecule H H • Methyl Group C H C H • Esters C H H C A H H C H H C • Fatty Acid H H C C H H B C H H C H H C H H C H H C H H • FAME: Fatty Acid Methyl Ester

12. Biodiesel Molecular Structure Let’s simplify this a bit… H H C H C H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H

13. Biodiesel Molecular Structure • First, let’s replace the methyl group with an Me. Let’s simplify this a bit… H H Me C H C H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H

14. Biodiesel Molecular Structure • First, let’s replace the methyl group with an Me. • The H’s representing the hydrogens can be removed from the diagram since it is assumed they are there. Let’s simplify this a bit… Me C H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H

15. Biodiesel Molecular Structure • First, let’s replace the methyl group with an Me. • The H’s representing the hydrogens can be removed from the diagram since it is assumed they are there. • The C’s representing the carbons can also be removed from the diagram since it is assumed they are there also. Let’s simplify this a bit… Me C C C C C C C C C C C

16. Biodiesel Molecular Structure • First, let’s replace the methyl group with an Me. • The H’s representing the hydrogens can be removed from the diagram since it is assumed they are there. • The C’s representing the carbons can also be removed from the diagram since it is assumed they are there also. • Make sure you know the methyl group and the fatty acid group. Let’s simplify this a bit… Me Biodiesel Fatty Acid Methyl Ester (FAME)

17. Fatty Acid Structure Carbon Chain Length • 1 carbon at every line intersection • Highly variable, even from the same plant H

18. Fatty Acid Structure H Carbon # Carbon Chain Length 1 2 3 4 5 6 7 8 9 10 11 12 • Remember – 1 carbon at every line intersection • Highly variable, even from the same plant • Usually from 12 – 18 carbons, can go up to 26 carbons • Usually in even numbers of carbons

19. Fatty Acid Structure H Carbon # Carbon Chain Length 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 • Remember – 1 carbon at every line intersection • Highly variable, even from the same plant • Usually from 12 – 18 carbons, can go up to 26 carbons • Usually in even numbers of carbons • Biodiesel properties are determined partially by chain length

20. Fatty Acid Structure Carbon Chain Bonds OH • Single bonds between the carbons O C C C C C C H H H H H H H H H H H • Saturated – No double bonds C H H H H H H H H H H H C C C C C H

21. Fatty Acid Structure Carbon Chain Bonds OH • Single bonds between the carbons O C C C C C H H H H H H H H • Saturated – No double bonds C H H H H H H H H • Double bonds between the carbons H H C • Unsaturated – Containing any double bonds H C C H • Monounsaturated – Containing 1 double bond C C C H

22. Fatty Acid Structure Carbon Chain Bonds OH • Single bonds between the carbons O C C C H H H H H • Saturated – No double bonds C H H H H H • Double bonds between the carbons H H C • Unsaturated – Containing any double bonds H C C H • Monounsaturated – Containing 1 double bond C H C C C • Polyunsaturated – Containing more than 1 double bond • Biodiesel properties are determined partially by chain bonds C H H

23. Fatty Acid Structure Carbon Chain Bonds OH O C • Carbon can only make four connections or bonds C C H H H H H C H H H H H H • No double bonds = two hydrogens • Two double bonds = no hydrogens • One double bond = one hydrogen H C H C C H C H C C C C H H

24. Basic Organic Oil Chemistry • The basic units of most naturally occurring organic oils are: • When 3 fatty acids bond with 1 glycerin molecule, you get a: • Glycerin • Fatty acids • Triglyceride

25. Basic Organic Oil Chemistry • The basic units of most naturally occurring oils are: • When 2 fatty acids bond with 1 glycerin molecule, you get a: • Glycerin • Fatty acids H • Triglyceride • Diglyceride

26. Basic Organic Oil Chemistry • The basic units of most naturally occurring oils are: • When 1 fatty acids bond with 1 glycerin molecule, you get a: • Glycerin • Fatty acids H H • Triglyceride • Diglyceride • Monoglyceride

27. Basic Organic Oil Chemistry • The basic units of most naturally occurring oils are: • When fatty acids are not bound to anything, you get: • Glycerin • Fatty acids H H H • Triglyceride • Diglyceride • Monoglyceride • Free fatty acids – FFA

28. Fatty Acid Structure Fatty Acid Structure Designations • General Format: A:B • A is the number of carbons in the fatty acid chain • B is the number of double bonds in the fatty acid chain

29. Fatty Acid Structure • Fatty Acid Structure Designations • 16:0 • (saturated) • General Format: A:B • A is the number of carbons in the fatty acid chain • B is the number of double bonds in the fatty acid chain • Example: Fatty acid with 16 carbons and 0 carbon to carbon double bonds (palmitic acid)

30. Fatty Acid Structure • Fatty Acid Structure Designations • 16:0 • (saturated) • 18:2 • General Format: A:B • A is the number of carbons in the fatty acid chain • B is the number of double bonds in the fatty acid chain • Example: Fatty acid with 16 carbons and 0 carbon to carbon double bonds (palmitic acid) • Example: Fatty acid with 18 carbons and 2 double bonds (linoleic acid) • (polyunsaturated)

31. Fatty Acid Structure • Fatty Acid Structure Designations • 16:0 • (saturated) • 18:2 • 16:1 • (monounsaturated) • General Format: A:B • A is the number of carbons in the fatty acid chain • B is the number of double bonds in the fatty acid chain • Example: Fatty acid with 16 carbons and 0 carbon to carbon double bonds (palmitic acid) • Example: Fatty acid with 18 carbons and 2 double bonds (linoleic acid) • (polyunsaturated) • Example: Fatty acid with 16 carbons and 1 double bonds (palmitoleic acid)

32. Fatty Acid Profile Fatty Acid Profile • Specific types of vegetable oils contain specific percentages of different fatty acids. • Important characteristics of the fatty acids: • 1) The percentage of fatty acids of different lengths, and: • 2) Percent of saturation/unsaturation Example: • Soybean oil • 11% - 16:0 • 4% - 18:0 • 24% - 18:1 • 54% - 18:2 • 7% - 18:3 = 75 % unsaturated 16:0 18:2 18:1

33. Fatty Acid Profile Fatty Acid Profile • Important characteristics of the fatty acids: • 1) The percentage of fatty acids of different lengths, and: • 2) Percent of saturation/unsaturation Example: • Coconut Oil • 7% - 8:0 • 6% - 10:0 • 47% - 12:0 • 18% - 14:0 • 9% - 16:0 • 3% - 18:0 • 6% - 18:1 • 2% - 18:2 = 92 % saturated 16:0 18:2 18:1

34. Fatty Acid Profiles Fatty Acid Composition of Vegetable Oils (percent of total fatty acids)

35. Fatty Acid Profiles Fatty Acid Composition of Vegetable Oils (percent of total fatty acids)

36. Fatty Acid Profiles Animal Fat Fatty Acid Profile http://www.iterg.com/IMG/pdf/CompositionAcidesGrasGraissesHuilesAnimales.pdf http://www.iterg.com/IMG/pdf/CompositionAcidesGrasGraissesHuilesAnimales.pdf

37. Fatty Acid Profiles Waste Vegetable Oil (WVO) • Can make excellent biodiesel • Challenges • Inconsistent composition • High level of free fatty acids, especially when heated beyond 300 ºF and/or exposed to water • Can be semi-solid at room temperature

38. Transesterification What is transesterification? • Big word, simple principle • Word breakdown • The exchange is catalyzed by potassium hydroxide, KOH. • Again, the specifics of the chemical reactions are beyond the scope of this course, but the principle isn’t. • Trans means “transferred or exchange.” • Ester means exactly that…ester. • Transesterification means to exchange the organic group on an ester with another organic group. • Here the exchange is the glycerin on the fatty acids with the methyl group from the alcohol, methanol.

39. Transesterification Methanol Molecules Triglyceride Molecule Me OH KOH KOH KOH Me OH Me OH Me OH Me OH

40. Transesterification Methanol Molecules Triglyceride Molecule Me OH Glycerin KOH KOH KOH Me OH Me OH Me OH Biodiesel (FAME) Me OH

41. Transesterification Triglyceride Oil Methoxide

42. Transesterification Triglyceride Glycerin KOH H H H Oil Methoxide Biodiesel Me Me Me

43. Transesterification Glycerin Me Me Me H H H Oil Methoxide Biodiesel Biodiesel Glycerin

44. Summary • Various types of oils can be used. • Some require preprocessing before transesterification. • Most oils are triglycerides which contain glycerin and fatty acids. • Contains methanol and potassium hydroxide (KOH). • Methanol provides methyl group. • KOH is a catalyst for the transesterification reaction. Feedstock Methoxide Solution • Trans means “transferred or exchange.” • Exchanges the glycerin on the fatty acids with the methyl group from the alcohol, methanol. • Leaves glycerin and fatty acid methyl esters (FAME) or biodiesel. Transesterification

45. Feedstock Pretreatment Pretreatment of Crude Vegetable Oil • Crude vs. Refined Vegetable Oil • Crude – Triglycerides, plus: • Free fatty acids • Phospholipids (gums) • Oxidation • Metals • Protein • Carbohydrate residues • Waxes • Moisture • Inorganic matter • Refined: Nearly pure triglycerides • <0.5% FFA

46. Feedstock Pretreatment Pretreatment of Crude Vegetable Oil • Degumming – Removing the phospholipids, waxes, and neutralizing the FFA) • First step in the vegetable oil refining process • Water – Causes some of the phospholipids and waxes to become insoluble in oil; separated via centrifuge • Acid – Used to extract remaining phospholipids and waxes • Base – Converts free fatty acids to soap and then removed via centrifugation or settling

47. Feedstock Pretreatment Pretreatment of Crude Vegetable Oil • Bleaching – Removal of trace metals, phospholipids, soaps, and other contaminants • Activated clay or silica • Deodorizing – Removal of trace FFA, pigments and other contaminants • Steam (210º C to 260º C)

48. Feedstock Pretreatment Pretreatment of WVO • Removal of solids and water • Solids removed via centrifugation and filtering • Water removed by heating (65º C) under vacuum

49. Feedstock Pretreatment • Pretreatment of High FFA Feedstocks • FFA >0.5% H • WVO • Animal fats • Palm oil • Jatropha oil • Why are free fatty acids in the oil a problem? • They use up the catalyst, so more catalyst is needed. • They produce soap during transesterification.

50. Feedstock Pretreatment • Pretreatment of High FFA Feedstocks • Difference Between Esterification and Transesterification • Esterification: A chemical reaction resulting in the formation of an ester • Converts FFA to FAME before transesterification can convert the FFA to soap • Catalyst: Acid instead of base (usually sulfuric acid) • Methanol • Esterification: Converts a non-ester into an ester • (e.g. FFA to FAME) • Transesterification: Converts an ester to a different ester • (e.g. Triglyceride to FAME)