Basic Chemistry of Ethanol Production p resented at CCURI Biofuels Workshop

1. Basic Chemistry of Ethanol 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 carbohydrates? What is glucose? Why is glucose important? What is starch? What is cellulose? How are the structures of starch and cellulose similar and how are they different? How is starch used to make ethanol? How is cellulose used to make ethanol? What are some of the more common feedstocks used for ethanol production?

3. Carbohydrates – Starch and Cellulose • What is a carbohydrate? • Organic compounds that contain only carbon, hydrogen, and oxygen • What do carbohydrates do? • Store energy (food) – starch (corn, potatoes) • Structural – cellulose (plant stems, wood) • Basic component of both starch and cellulose? • Glucose

4. Glucose Basic Structure = Oxygen = Carbon = Hydrogen

5. Glucose Basic Structure = Oxygen = Carbon

6. Glucose Basic Structure 6 = Oxygen = Carbon 5 1 4 3 2

7. Glucose Basic Structure • Glucose – Important Facts • Also called “fermentable sugar,” “dextrose,” “corn sugar” or “sugar” • Used by biological systems as food • It is a “monomer” – Mono means “one” or “single.” • Starch is a “polymer” – Poly means “many.”

8. Monomers What is a monomer? • One unit of a string of units

9. Monomers What is a monomer? • One unit of a string of units • Example: Pearl necklace • If a monomer is 1 unit of a string of units, then what is the monomer of a pearl necklace?

10. Monomers What is a monomer? • One unit of a string of units • Example: Pearl necklace • If a monomer is 1 unit of a string of units, then what is the monomer of a pearl necklace? • A pearl!

11. Polymers What is a polymer? • A string of similar units

12. Polymers What is a polymer? • A string of similar units • Example: Pearl necklace • If a polymer is a string of similar units, then what is the polymer of a pearl?

13. Polymers What is a polymer? • A string of similar units • Example: Pearl necklace • If a polymer is a string of similar units, then what is the polymer of a pearl? • A pearl necklace!

14. Monomers and Polymers • The pearl is a monomer • When connected with other pearls they make a polymer called a pearl necklace • Same principle applies to chemicals • Glucose is a monomer • When connected with other glucose molecules they make a polymer called starch or cellulose

15. Starch is a polymer • > 500 glucose units • Two types of starch

16. Starch is a polymer • > 500 glucose units • Two types of starch • Amylose – straight chains

17. Starch is a polymer • > 500 glucose units • Two types of starch • Amylose – straight chains • Amylopectin – branched chains

18. Starch vs. Cellulose Structure Starch Structure 6 6 6 6 5 5 5 5 6 6 4 4 4 4 1 1 1 1 5 5 3 3 2 2 3 2 3 3 3 2 2 2 4 4 1 4 1 1 1 4 Cellulose Structure 5 5 3 2 3 2 6 6

19. Cellulosic Structure Cellulose Structure Glucose Molecule

20. Cellulosic Structure Cellulose Structure Individual Cellulose Molecules Glucose Molecule

21. Cellulosic Structure Cellulose Structure Individual Cellulose Molecules Glucose Molecule

22. Cellulosic Structure Cellulose Microfibril Cellulose Structure Lignin Individual Cellulose Molecules Glucose Molecule

23. Cellulosic Structure Cellulose Microfibrils Cellulose Structure Lignin Individual Cellulose Molecules Non-cellulose Polysaccarides Cellulose Fiber Glucose Molecule

25. Lignin Structure • Very complex structure • Second most common molecule on earth. • Lacks a defined structure • Fills the spaces between cellulose

26. Hemicellulose Structure

28. Enzymes are proteins that speed up chemical reactions, but are not altered themselves (catalysts) Enzymes

29. Enzymes are proteins that speed up chemical reactions, but are not altered themselves (catalysts) Enzymes

30. Enzymes are proteins that speed up chemical reactions, but are not altered themselves (catalysts) Enzymes

31. Enzymes are proteins that speed up chemical reactions, but are not altered themselves (catalysts) Enzymes Reaction can go either way

32. Glucose Linkages and Enzyme Active Sites

33. Glucose Linkages and Enzyme Active Sites

34. Glucose Linkages and Enzyme Active Sites

35. Glucose Linkages and Enzyme Active Sites 6 5 1 4 2 3

36. Named for the way two glucose molecules are attached to each other. Glucose Linkages and Enzyme Active Sites 6 5 1 4 2 3 1,6 linkage 1,4 linkage

37. Amylopectin – Branched Starch Molecule

38. Amylopectin – Branched Starch Molecule Introducing the enzymeα-amylase.

39. Amylopectin – Branched Starch Molecule Introducing the enzymeα-amylase. α-amylase breaks down starch into shorter glucose chains called “dextrins.” Breaks 1,4 linkages that are not terminal.

40. Amylopectin – Branched Starch Molecule Introducing the enzymeα-amylase. Dextrins Dextrins Dextrins α-amylase breaks down starch into shorter glucose chains called “dextrins.” Breaks 1,4 linkages that are not terminal.

41. Dextrins Dextrins Dextrins

44. Introducing the enzyme glucoamylase.

45. Introducing the enzyme glucoamylase. Glucoamylase breaks down dextrins into individual glucose molecules. Acts on 1,4 and 1,6 terminal linkages.

47. What about Cellulose Since starch and cellulose are glucose polymers, why is cellulose so much harder to break down into glucose? So how do we get through the other stuff to get to the cellulose? Once we get to the cellulose, will the same enzymes work?

48. Cellulose Pretreatment Options Physical Breakdown (heat/pressure, grinding, chopping, sonication) Weak Caustic (NaOH, Ammonia) Weak Acid (Sulfuric, HCL) Heat with caustic and acid Pressure and heat with caustic and acid Enzymatic cocktails (cellulases, zylases, gluconases, ligases, hemicellulases, etc). Usually used after at least one of the above. Time can vary on all of these.

49. Cellulose as Other Forms of Fuel Straight Combustion – Most common Pyrolysis (bio-oil)– Usually high temps and pressures. Some low temp technologies. Syngas – Gasification of organic material at high temps (without combustion) with oxygen and steam to produce CO, H, and CO2

50. Ethanol Feedstocks