Organic Chemistry

Fossil Fuels

Fossil Fuels

• Fossil fuels form the major part of our fuel resources

• They are derived from the fossil remains of living organisms which have been altered by heat and pressure

World Proven Reserves of Crude Oil

63.7

89.5

20.6

74.9

65.4

44.0675.7

thousand million barrels

World Proven Crude Oil Reserves

Europe2%

North America 6%

South & Central America

9%

Middle East66%

Asia & Pacific4%

Former Soviet Union6%

Africa7%

as percent of 1296 thousand million barrel total

Natural Gas

• Formed in large deposits under the sea, usually together with petroleum

• 90% methane and needs very little treatment before use.

• Used mainly for heating houses and energy production

• Piped from the deposit to the land

Coal

• Vast deposits of coal in the Latrobe Valley Victoria are used to produce electricity.

Oil

• Crude oil is the petroleum that is pumped directly from the ground.– It is a complex mixture of hydrocarbons with

one or two carbon atoms up to a limit of about 50 carbon atoms.

– This is usually not useful, so it must separated by distillation.

• Crude Oil• This is a main part of this section due to it being used

widely, all over the world, however is a non-renewable source. It is a mixture of chemicals that are not chemically bonded (hence it is a mixture), but are still together.

•   A hydrocarbon - A molecule that contains only hydrogen and carbon

• Alkane - A saturated hydrocarbon• Mixture - More than one substance chemically bonded

• Crude oil from the ground is separated into usable groups of hydrocarbons at this refinery. Each petroleum product has a boiling point range, or "cut," of distilled vapors that collect in condensing towers.

Petroleum

• Petroleum is a mixture of alkanes, cycloalkanes, and aromatic hydrocarbons.– Petroleum is formed from the slow decomposition

of buried marine life, primarily plankton and algae.

• As petroleum is formed it is forced through porous rock until it reaches an impervious layer of rock.– Here it forms an accumulation of petroleum and

saturated the porous rock creating an oil field.

Petroleum

• Petroleum was once used for medicinal purposes.– It was first distilled by running through a

whiskey still, in an attempt to make it taste better.

– The liquid that he obtained burned quite well in lamps.

– This clear liquid that was obtained from petroleum distillation was called kerosene.

• Crude oil is a mixture of many different hyrocarbon lengths and we can use fractional distillation to separate them into their separate lengths for their unique uses. The hydrocarbons in crude oil with longer lengths (more carbon atoms) are more viscous and therefore have higher boiling points. This factor means that using the fractions boiling points, the fractionating column can separate out the crude oil according to the different temperatures it boils.

• The process is as follows:• Crude oil is pumped into the distillary vapourised

– It enters the column at 340 degrees celcius where the bitumen or residue which is the most viscous condenses, coming out of the bottom

– Oil then condenses slighly higher up the tower at 340 degrees celcius. It has a 35 molecule length and is fractioned off away from the rest of the mixture

– Next, diesel condenses at 250 degrees celcius with its 20 molecule length where it is filtered out

– Kerosene at 180 degrees celcius condenses and is sectioned off with its 15 molecule length

– Naptha is next to condense at 110 degrees celcius with 10 molecules in it's chain

– Petrol at 40 degrees is sectioned off with 8 molecules – Finally, refinery gas is sectioned off at the top of the tower with it's

3 molecules. This short molecule length is what makes it a gas.

• Petroleum products and the ranges of hydrocarbons in each product.

Composition of Crude Oil

CRUDE OIL

HYDROCARBONS NON-HYDROCARBONS

ALIPHATICS AROMATICS NAPHTHENES SULFURS NITROGENS OXYGENS METALLICS

25% 17% 50% <8% <1% <3% <100PPM

C1 - C60 (C6H5)n CYCLOALKANESSH

S

NH

O

COOH

The Uses of Crude Oil

Uses of Crude Oil

Gasoline Distillate Fuel Oil

Kerosene J et Fuel Residual Fuel Oil

Liquefied Refinery Gases Still Gas

Coke Asphalt and Road Oil

PETROCHEMICAL FEEDSTOCKS Lubricants

Kerosene Other

Uses of Crude Oil

Gasoline Distillate Fuel OilKerosene Jet Fuel Residual Fuel OilLiquefied Refinery Gases Still GasCoke Asphalt and Road OilPETROCHEMICAL FEEDSTOCKS LubricantsKerosene Other

CRUDE

DESALTING

REFINING

REFORMING

BLENDING

Distillation to separate by boiling point ranges

Water washing to remove impurities

Conversion reactions to alter molecular structures

Mixing to obtain maximum commercial characteristics

Petroleum delivered from well field

Petroleum Refining

GAS

LIGHT NAPHTHA

HEAVY NAPHTHA

KEROSENE

ATM. GAS OIL

RESIDUUM

CRUDE DESALTER FURNACE

C1-C4

bp < 50 oF

C5 - C?

bp 50-200oF

C? - C12

bp 200-400oF

C12 - C16

bp 400-500oF

C15 - C18

bp 500-650oC

> C20

bp >650oF

TOWER

Distillation – separation by boiling point

Petroleum ReformingGAS

LIGHT NAPHTHA

HEAVY NAPHTHA

KEROSENE

ATM. GAS OIL

RESIDUUM

TOWER

FUEL GAS

TREATER

HYDROTREATER

HYDROTREATER

HYDROTREATER

REFORMER AROMATIC EXTRACTION

CATALYTICCRACKER

JET FUELS/KEROSENE

DIESEL & FUEL OILS

GASOLINE

AROMATICS

VacuumDistillation

VACUUM GAS OIL

LUBRICATING OIL

COKER COKE

ASPHALT

CATALYTICCRACKER

Conversion Reactions

gasoline gasoline additive recycle

C7H15.C15H30.C7H15 C7H16 + C7H14 + C15H30CRACK

COMBINE

REARRANGE

THERMAL

CATALYTIC

ALKYLATION

POLYMERIZATION

REFORMIING

ISOMERIZATION

CH3CH2CH3 CH2 CH CH2 CH3CH3CH2CH2 CH2CH2CH2CH3

C H3C

CH3

CH2C H3C

CH3

CH2C H3C

CH3

CH3

C CH2

CH3

H

CH2C CHCH3

CH3CH3

CH3

H3CC

82% 18%

Dehydrogenation

Dehydroisomerization

Isomerization

Dehydrocyclization

Hydrocracking

Catalytic Reforming – Conversion ReactionsDehydrogenation of cycloalkanes to aromatics

Dehydroisomerization of cyclopentanes to aromatics

Isomerization of alkanes

Dehdrocyclization of alkanes

Hydrocracking of alkanes

CH3 CH3

3H2

CH3

3H2

CH3CH2CH2CH2CH3 CHH3C

CH3

CH2 CH3

CH3CH2CH2CH2CH2CH2CH3

CH3

4 H2

CH3CH2CH2CH2CH2CH2CH3 CH3CH2CH3 CH3CH2CH2CH3

Refining Crude Oil

Review

• Complete the revision questions page 188 (40 – 43)

• Complete the revision questions page 190 (44 – 46)

• Complete the multiple choice questions pages 191 – 192

• Complete the review questions 2, 3, 4, 7, 8, 10, 11, 13, 15, 17, 18

• Complete the exam practice questions