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Development of Supports
The improvement over time has been as much to do with the supports as with the catalysts themselves

Development of ceramic and metallic supports with thinner walls and increased catalyst surface       

   image: development of ceramic and metallic supports with thinner walls and increased catayst surface    image: development of ceramic and metallic supports with thinner walls and increased catayst surface

A larger catalyst surface area can be fitted into a given converter volume. This gives better efficiency and durability.

Alternatively, the same performance can be obtained from a smaller converter

This makes the catalyst easier to fit close to the engine in small cars.

The thin walls reduce the amount of heat absorbed, so temp stays higher

Question

By how many times has the wall thickness been reduced?

How many times has the cell density been increased?

What benefits do you think these advances in materials technology bring?

A wide range of shapes and sizes
image: catalyst supports, a wide range of shapes and sizes
Year Material Number of cells per cm2 Wall thickness (mm)
1974 Ceramic
200
0.305
Late 1970s  
400
0.153
2001  

400
600
900

0.05
Late 1970s

Steel
Ultra fine corrosion resistant foil

600
0.05
2001  
800
1000
0.025

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