Mainly high surface area
Catalyst lower the activation energy in a reaction, and therefore allow it to take place at lower temperatures as less energy is needed. The catalytic converter is made of platinum, palladium or rhodium. The converter is also arranged in a hexagon structure, similar to that of a beehive. This means that there is the highest surface are to volume ratio possible, and so more surface for the reaction to occur on and therefore optimise the efficiency of the space available.