15 – Oil Refining & Its Products

1. 15 – Oil Refining & Its Products Leaving Certificate Chemistry

2. Fractional Distillation

3. Crude Oil Crude oil is, by itself, relatively useless. It is a sticky, smelly, viscous liquid which is a mixture of thousands and thousands of hydrocarbons of different lengths

4. Fractional Distillation This separation is called fractional distillation (Fractionation) This process is carried out in an oil refinery (as shown opposite) Different fractions are separated on the basis of them having different boiling points

5. An oil refinery in California

6. Whitegate Oil Refinery, Cork (ConocoPhillips, Texas) 71,000 Barrels Per Day

7. Oil storage facility, Whiddy Island, Bantry Bay

8. Who uses the most oil? World’s biggest oil consumers (per thousand barrels per day)

9. Who owns the most oil? 2006 Proven Reserves (billion barrels)

10. The vapours containing the lightest molecular weight hydrocarbons rise to the top of the tower. The higher the molecular weight of the hydrocarbons, the lower the level to which they rise. The Crude Oil is heated and vapourised in a furnace The hot vapours go into a large distillation tower.

12. Fractions: Refinery Gas This fraction mainly consists of the gases methane, ethane, propane and butane. Propane and butane are mixed together and sold as liquid petroleum gas (LPG)

14. Fractions: Naphtha This fraction (Naphtha) mainly consists of the mixture of liquids of hydrocarbons of carbon lengths 8 to 15 Naphtha is a common fuel and also used for making chemicals such as plastic

16. Fractions: Gasoline This fraction (Gasoline) mainly consists of the mixture of liquids of hydrocarbons of carbon lengths 5 to 12 So pentane (C5) and its isomers would be found in gasoline We know gasoline to be ‘petrol’ – used to power automobiles (cars, trucks, etc…)

18. Fractions: Kerosene This fraction (Kerosene) mainly consists of the mixture of liquids of hydrocarbons of carbon lengths 12 to 15 Kerosene is used as a fuel for aircraft, heating & cooking.

20. Fractions: Gas Oil This fraction (Gas Oil) mainly consists of the mixture of liquids of hydrocarbons of carbon lengths 16 and higher. Gas Oil consists of hydrocarbons of relatively long chains of carbon atoms. Gas Oil is used as a fuel for ships.

22. Fractions: Residue This fraction (Residue) mainly consists hydrocarbons of very long carbon lengths 80 and higher. Bitumen is used as to surface roads.

23. A barrel of Oil

24. Common fuels & their composition

25. Natural Gas Methane (95%) Ethane Propane & Butane are also present in small amounts Mercaptans are chemicals deliberately added to give natural gas a smell as it is otherwise odourless.

26. Liquid Petroleum Gas (LPG) Propane Butane Ethane Propane & Butane make up liquid petroleum gas (LPG)

27. Composition of Petrol • Petrol is obtained from the gasoline fraction and from the naptha fraction from fractional distillation • It is a mixture of hydrocarbons (mainly alkanes) of between carbons lengths 5 to 10

28. The Octane Number of a Fuel

30. The Internal Combustion Engine When the petrol and oxygen mixture ignites and explodes evenly and at the correct time the engine runs smoothly. http://upload.wikimedia.org/wikipedia/commons/a/a6/4-Stroke-Engine.gif

31. Engine Knocking Knocking is noises coming from the car It is a sign that the petrol and air mixture in the engine is burning too soon or not exactly as intended This reduces the efficiency of the engine and over time can cause serious damage.

32. The Octane Number of a Fuel

33. The Octane Number of a Fuel The higher the octane number the smoother it burns and the less likely knocking will occur. The lower the octane number the less likely it burns smoothly and so the more likely knocking will occur.

34. Reference Hydrocarbons for assigning octane numbers

35. Octane Numbers of hydrocarbons Octane Number = - 10 Octane Octane Number = 0 Heptane

36. Octane Numbers of hydrocarbons Octane Number = 25 Hexane Octane Number = 62 Pentane

37. Conclusion 1 • The shorter the carbon chain the higher the octane number and the longer the carbon chain the lower the octane number

38. Octane Numbers of hydrocarbons Octane Number = - 10 Octane Octane Number = 100

39. Conclusion 2 • The greater the amount of branching in the chemical structure the higher the octane number and the less branching the lower the octane number

40. Octane Numbers of hydrocarbons Benzene Cyclohexane Octane Number = 101 Octane Number = 97

41. Conclusion 3 • Ring & Aromatic Compounds have high octane numbers

42. Octane Numbers of other Fuels Methanol Ethanol Octane Number = 113 Octane Number = 117

43. Ethanol used as a biofuel in Brazil

44. Conclusion 4 • Oxygen containing organic compounds (oxygenates) have very high octane numbers

45. Improving the octane number of a fuel – Addition of Lead Compounds • For years adding lead compounds (like tetraethyl-lead) to fuels rapidly improved the octane numbers of those fuels. • This no longer occurs as the addition of lead to petrol has been banned in Ireland since 2000.

46. Why Lead Compounds are no longer added to petrol As Lead compounds destroy the catalysts which make up the catalytic converter of the car (automobile) Lead is a highly toxic chemical to living things.

47. Refining the Octane Number of a Fuel • There are 4 ways a fuel (or chemical) may be refined to improve the octane number of that fuel (chemical): • 1: Catalytic Cracking • 2: Reforming • 3: Isomerisation • 4: Addition of Oxygenates

48. Catalytic Cracking Cracking is the changing of long-chained hydrocarbons (like from heavy gas oil fraction) to more useful short-chained hydrocarbons

49. Reforming & Ring Formation (Dehydrocyclisation) The structure of hydrocarbon molecules with low octane numbers is re-shaped to give molecules with high octane numbers

50. Isomerisation Isomerisation involves breaking molecules, usually straight chain alkanes, up into pieces and rejoining them again to produce new molecules, which are usually branched chain alkanes. This increases their octane rating.