TWC Catalyst Design: Monoliths
Design of the catalyst support is as important as fuel mixture control and catalytic chemistry. From the perspective of plug flow reactor design, key issues/design parameters are:
space velocities from 10,000 to 100,000 l/hr depending on engine size and mode of driving
minimal pressure drop for improved engine output
low thermal inertia for quick heat up
Materials design issues include:
stability at to temperatures up to 800°C
ability to withstand rapid heating
surface area, metal dispersion and resistance to sintering
mechanical properties sufficient to last 160,000 km of use.
Most catalytic converters are constructed from ceramic monolithic supports of a magnesium aluminum silicate.