Ceramic Foam Catalytic Converters
Ceramic foam is a relatively new alternative for making the substrates which are at the core of catalytic converters. Ceramic foam substrates have an irregular appearance like a sponge, which means that gases passing from one side to the other are forced to take a convoluted path. This causes turbulence which increases the likelihood of particles and molecules in the gas making contact with the surfaces of the substrate instead of passing straight through.
For this reason, foam substrates can give a greater conversion of pollutants than conventional honeycomb substrates, especially for larger particles such as condensed droplets of oil. They may also help to arrest and extinguish glowing embers or sparks. The downside is that they cause a greater pressure drop than a conventional honeycomb substrate, although this can be compensated for by experimenting with different diameters, lengths and pore densities.
Foam substrates are ideal for use in wood stoves and wood-fired cooking appliances such as pizza ovens, especially if the flue is fan-assisted.