A Three Way Filter (TWF®) is a gasoline particulate filter (GPF) with a JM catalyst coating. Gasoline vehicles fitted with Johnson Matthey TWF technology can reduce particle numbers by up to 99%.
A TWF also displays catalytic activity, providing significant reductions of gaseous emissions (HC, CO, NOx), as well as filtration of fine particles.
[CO] + O2 → CO2
[HC] + O2 → CO2 + H2O
[NOx] + H2 → N2 + H2O
Composition: Typically precious metals (Pd, Pt or Rh) with alumina and rare earth oxide, coated on filter substrate.