Additional benefits of catalytic converters
The increasing use of catalytic converters required the introduction of more sophisticated engine control technologies. These have allowed automobile manufacturers to design engines for higher fuel efficiency, promoting a continuous rise in fuel economy which will continue to be important as manufacturers strive to meet more demanding fuel economy and CO2 regulations.
Sulphur in gasoline and diesel fuel has a major negative impact on catalyst performance and also contributes to the mass of particulate matter (PM). The effect of sulphur on catalyst performance becomes more critical as lower tailpipe emissions are targeted and the loss of catalyst efficiency caused by sulphur in the fuel has a greater impact at the very low emissions levels required in the most advanced emissions regulations. For this reason European legislation has limited on-road and non-road fuel sulphur content to 10ppm (max.). In the US, the limit is 15ppm (max.) for diesel and will be 10ppm for gasoline when EPA Tier 3 regulations take effect from 2017.
In addition, because the catalyst is poisoned by lead, the introduction of catalytic converters on vehicles helped bring about the elimination of lead-containing gasoline additives, which were found to be a serious health hazard.