Catalytic Converters - PowerPoint Presentation

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