• To reduce the amount of pollutants released in car exhaust fumes, many cars are now fitted with?catalytic converters
• Precious metals (such as platinum) are coated on a honeycomb to provide a?large surface area
• The reactions that take place in the catalytic converter include:
• • Oxidation of unburnt hydrocarbons:

   

CnH2n+2?+ (3n+1)[O] → nCO2?+ (n+1)H2O

• • ?Oxidation of CO to CO2:

2CO + O2?→ 2CO2

or

2CO + 2NO → 2CO2?+ N2

• • Reduction of NO to N2:

2CO + 2NO → 2CO2?+ N2

Catalytic removal of NOx?and CO

• Carbon monoxide and the nitrogen oxides released through cars’ exhaust fumes?pollute?the atmosphere
• The nitrogen oxides are?reduced?on the surface of the?hot catalyst?to form the unreactive and harmless nitrogen gas which is then released from the vehicle’s exhaust pipe into the atmosphere
• The chemical reaction for the reduction of nitrogen oxide to nitrogen gas by the catalyst is as follows:

2CO (g) + 2NO (g) → 2CO2?(g) + N2?(g)

A catalytic converter helps reduce the pollutants from motor vehicles

• Reducing pollution from the combustion of fossil fuels and the limited amount of?non-renewable fossil fuels?are two reasons for finding alternative fuels
• Biofuels are?renewable?fuels
  • Renewable meaning that they can be replaced over a short period of time
  • The bio part of biofuel meaning that it comes from living matter
• The three main biofuels are?biodiesel,?bioethanol?and?biogas
  • Biodiesel - made by refining renewable fats and oils
  • Bioethanol - made by fermentation
  • Biogas - made / released when organic waste breaks down

Benefits of biofuels

• Biofuels are often considered as?carbon neutral
  • This is because as the plants grow they absorb carbon dioxide which is equivalent to the amount of carbon dioxide that will be released when they are burnt
  • This is not completely correct because carbon dioxide will also be produced in the refining and transport of the plants
• Biodiesel and biogas can reduce the amount of waste going to landfill as the waste can be used to produce them
• Biofuel production could provide money for less developed countries as they have the space to grow the crops required

Drawbacks of biofuels

• The cost of converting engines and machinery to run on biofuels instead of petrol / diesel
• Many developed countries don't have the space to be able to produce enough plants to make the biofuels because the land is needed for food production