How did fossil fuels form? Summarise on a MWB Starter How did fossil fuels form? Summarise on a MWB

Formation of fossil fuels

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Presentations 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 in fuels 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 Dissolved in basic potassium carbonate solution 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?

Answers H2S(g) + CO32- (aq)↔ HS- (aq) + HCO3-(aq) 2H2S(g) +3O2(g)  2SO2 (g) + H2O (l) 2H2S(g) + SO2  3S (s) +2H2O (l)

Cracking Use heat or a catalyst

Hydrocracking 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.

Zeolite

Zeolite 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

Additional information

Four stroke engine

Knocking youtube

Octane Rating Fuel’s ability to resist engine knocking Definition Fuel’s ability to resist engine knocking Compared to volumetric mixture of iso-octane and n-heptane Iso-octane (2,2,4-Trimethylpentane) C8H18 Heptane (n-Heptane) C7H16 Example 87 gasoline from pump should have the same octane rating as 87% iso-octane and 13% heptane.

Increasing the octane number Adding lead Alkylation

Alkylation

Isomerisation

Summary

Coal gasification Coal gas used to be used before natural gas Coal was reacted with steam to make carbon monoxide and hydrogen. Both of which are combustible gases. Its known as town gas and still used today

When the oil runs out…

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Carbon footprint Discuss the following

Carbon footprint What is your carbon footprint http://www.nature.org/greenliving/carboncalculator/

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Exercises

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Answers part 2