How did fossil fuels form?
Summarise on a MWB
Formation of fossil fuels
You have ten minutes to prepare a short presentation on one
of the following
• Group 1
Crude oil refinement (Fractional distillation and
desulfurisation)
• Group 2
Cracking (catalytic, thermal, steam and hydrocracking)
• Group 3
Octane numbers, knocking, leaded and unleaded
• Group 4
Zeolites
• Removal of sulphur from liquid fuels (especially
diesel) is very important
• If sulphur is not removed it stops catalytic
converters from working properly
• Massive reduction in SO2 pollution from diesel
engines
• Better fuel efficiency (oxygen and energy are not
wasted on oxidising sulphur)
• Removal of sulphur from crude oil (or its fractions) is
commercially important, as sulphur is used to
produce sulphuric acid (no. 1 industrial chemical)
• Huge reduction in local SO2 emissions and local acid
rain production from vehicle exhausts
Removing acidic hydrogen sulfide
1. Dissolved in basic potassium carbonate
solution
2. It can also be burned in air to form sulfur
dioxide. That can then be reacted with more
hydrogen sulfide to produce elemental sulfur
Can you write the three equations
describing what happens above?
1. H2S(g) + CO32- (aq)↔ HS- (aq) + HCO3-(aq)
2. 2H2S(g) +3O2(g)  2SO2 (g) + H2O (l)
3. 2H2S(g) + SO2  3S (s) +2H2O (l)
• Use heat or a catalyst
• Hydrocracking is a catalytic chemical process used in petroleum refineries
for converting the high-boiling constituent hydrocarbons in petroleum
crude oils to more valuable lower-boiling products such as gasoline,
kerosene, jet fuel and diesel oil.
A large group of minerals
consisting of hydrated
aluminosilicates of sodium,
potassium, calcium, and barium.
They can be readily dehydrated
and rehydrated, and are used as
cation exchangers and molecular
sieves.
They are good catalysts for
cracking etc
• Knocking youtube
Definition
• Fuel’s ability to resist engine
knocking
• Compared to volumetric mixture
of iso-octane and n-heptane
Example
• 87 gasoline from pump
should have the same
octane rating as 87% isooctane and 13% heptane.
Iso-octane
(2,2,4-Trimethylpentane)
C8H18
Heptane
(n-Heptane)
C7H16
• Adding lead
• Alkylation
Discuss the following