NOx Aromatics Effects in Catalyst-Equipped Gasoline Vehicles

Investigations into fuel compositional effects on emissions using model and full range fuels suggest aromatic components promote NO_x conversion over the catalyst

Steady state results derived from a single engine (Ricardo Gasoline Fuels Consortium data) show that at a typical part load condition, the catalyst removes NO_x less effectively with lower aromatic fuels. Neither CO nor H₂ contribute significantly to catalyst performance.

Two vehicles were tested over a European cycle. Toluene formed more combustion chamber NO_x, offset by increased catalyst conversion efficiency giving lower tailpipe NO_x than isooctane in the vehicle with the better catalyst light-off and AFR control.