and poisons Rates of Reaction Catalytic Converters Exhaust fumes contain CO due to incomplete combustion of hydrocarbons NO amp NO 2 N 2 in air is oxidised at high temperatures ID: 572456
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Slide1
Catalytic Converters
and
poisonsSlide2
Rates of Reaction
Catalytic Converters
Exhaust fumes contain
CO –
due
to incomplete combustion of hydrocarbons
NO & NO
2
–
N
2
in air is oxidised at high temperatures
Unburned hydrocarbonsSlide3
Learning Check
Can I name the 4 impurities in exhaust fumes?
Can I say why each one is present?Slide4
Rates of Reaction
Catalytic Converters. . .cont’d
Important to decrease emissions as
CO – poisonousNO & NO
2
– toxic and contribute to acid rain
Unburned hydrocarbons – contribute to photochemical smogSlide5
Rates of Reaction
Check ….
Say the problem caused by each of the 4 impurities
CO …….NO and NO2…….
Unburned hydrocarbons……Slide6
Rates of Reaction
Catalytic
converters convert
…..CO, NO and NO2 into harmless gases.2CO + 2NO
2CO
2
+ N
2
HC’s + NO + NO
2
CO2 + N2 + H2OThis is example of heterogeneous catalysis – which phases present?. They consist of a thin coating of Rh, Pd or Pt on a ceramic or metal honeycomb steel case which has a large surface area.
Rh / Pd / Pt
Rh / Pd / PtSlide7
Rates of Reaction
Check ….
Write the balanced chemical equation for the removal of
CO and NO …….Write a word equation for the removaal of
Unburned
hydrocarbons, NO and NO
2
…….Slide8
Rates of Reaction
Catalytic Poisons
Impurities
in a reaction mixture adsorb onto the surface of a catalyst thus
blocking
(removing)
potential sites
for gas
molecules
and decreasing efficiencyExpensive the catalyst has to be replaced (Pt costly) or the process has to be shut downExamples sulphur (Haber process)
lead (Catalytic converters in cars)Slide9
Rates of Reaction
Check ….
What is a catalytic poison?
How does it stop the catalyst workingWhy is it undesirable to poison the catalytic converter?Example of poison for cat converter in carSlide10
Also Check ….
Do I know ….
Why catalytic converters are recycled?
Another reason for cat converters not working other than poisons?Slide11
The End