By how much do they reduce pollution?
By most estimates, catalytic converters fitted inside the exhaust pipe of a gasoline-operated car convert over 90% of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) from the engine into less harmful carbon dioxide (CO2), nitrogen and water vapour. Diesel engines, in addition, emit particulates. The use of a particulate filter, in conjunction with a catalyst, can reduce their mass by 90% and reduce the number of ultra-fine particles by 99%.
PGMs support emissions regulations
Due to the catalytic properties of PGMs it has been possible for legislators to mitigate the effects of exhaust pollution from increasing numbers of vehicles on our roads. Emissions regulations have been progressively tightened to the extent that just one car sold in the 1960s would have produced as many harmful exhaust emissions as one hundred of today's automobiles equipped with catalytic converters.
As the number of cars throughout the world increases, further cuts in pollution per vehicle are needed to keep improving air quality. This tightening of emissions continues: for example, EURO 6 regulations for light duty vehicles in Europe, which start in 2015, require more than a 50% reduction in NOx emissions over the current EURO 5 regulations.
For gasoline engines, the California LEV III (SULEV III) regulations, which also start in 2015, require more than a 70% reduction in CO emissions compared to the US Federal Tier 2 Bin 5 regulations.
Many governments in the fast growing emerging markets of Brazil, India, and China – the BRIC countries –, are putting legislation in place to catch up with the standards already implemented in the US, Europe and Japan. Catalysts are now also required on construction and agricultural equipment in many markets.
More information on Emissions Control can be found here.