There are millions of cars running around in this world. Dumping the pollutants into the environment. Needless to say these pollutants are ruining our health as well as our planet’s.
To solve the problem, car manufacturers took this social responsibility and designed a device, catalytic converter in 1975, which converts the harmful pollutants into less harmful ones by breaking their molecules before they get emitted into the environment.
What does CAT do?
The modern car takes into consideration the amount of fuel they use while the engine is running the car, and use Catalytic Converter as a medium to save the environment by ejecting out less harmful gases into the atmosphere.
The harmful gases which are converted by catalytic converter are:
- Carbon monoxide CO, colorless and odourless poisonous gas.
- Hydrocarbons major component of smog which also leads to respiratory problems.
- Nitrogen oxides major cause of acid rains which leads to blisters and other skin problems.
These harmful molecules are broken down and converted into
- Nitrogen gas, our atmosphere consist of 78% N2.
- Carbon Dioxide – Carbon molecules which then bonds with oxygen in the air to form carbon dioxide which is also a major cause of global warming.
- Water – again the hydrogen in the pollutants bonds with the oxygen and leave the car’s exhaust system as water vapour.
How Does CAT work?
As the name suggests, Catalytic converter works in the presence of a catalyst. A catalyst is an agent that supports or accelerates a chemical reaction without itself getting affected.
There are two types of catalyst reactions that happens in a CAT, a reduction catalyst and oxidation catalyst. The structure of a catalytic converter is usually a ceramic structure coated with platinum, rhodium or palladium.
- In the reduction catalyst nitrogen oxide atoms are splitted from oxygen atoms this reaction uses platinum and rhodium.
- Next is the oxidation reaction where unburnt hydrocarbons and carbon monoxide gets converted into carbon dioxide in the presence of platinum and palladium as a catalyst.
Shortcomings
This honeycomb monolith coated with precious metal structure (CAT) is contributing in saving the environment to a great extent.
But there are shortcomings associated with every technology
- This arrangement works best at very high temperature, hence when the vehicle is started the engine is cold, the catalyst converter does nothing in this situation.
- Secondly, it doesn’t work well with diesel engines as they are comparatively cooler than the standard engines. Hence, diesel vehicles use diesel particulate filters (DPF).
DPF – Diesel Particulate Filters
Mainly used in diesel vehicles, this device has channels which blocks the incoming pollutants at alternate ends. In order to exit the filter, the pollutants are forced to pass through the cells wall which are porous in nature.The clean gases pass through and other pollutants gets trapped in the filter. A engine management system that constantly monitors the filter to prevent it from blocking.
