Volvo Catalytic Converter, Anyone?

by EVANDER KLUM

There are three major pollutants generated by motor vehicles and they spring from three sources. There are the hydrocarbon emissions that spring from crankcase fumes (blowby). Then, there are those that come from the fuel system evaporation which involves the carburetor and gas tank. The third comes from the exhaust system. Carbon monoxide as well as oxides of nitrogen comes solely from the engine exhaust. The emissions system, then, tries to reduce the effects that these materials have on the environment. One of the most notable members of the system is the catalytic converter. The case is no different for a Volvo catalytic converter.

To meet the post-1975 exhaust emission standards for HC and CO, most 1975 and later cars soled in the US and Canada had catalytic converters. The converters contained a catalyst made up of platinum or palladium that promoted an oxidizing chemical reaction. This reaction caused the HC and CO in the exhaust to combine with oxygen and form water and carbon dioxide. The catalyst was deposited on a substrate material in the converter housing. The converter was installed in the exhaust system ahead of the muffler. The very first oxidation catalytic converters used on most 1975 as well as later cars were not effective against NO emissions. NO control requires a process that removes oxygen from the oxides of nitrogen.

In 1977 as well as in 1978, some car makers began to limit the use of the three-way catalytic converters to control all three major pollutants. These oxidation-reduction converters, combined with computerized-air fuel control and or electronic spark timing, have seen increased use, while the cars that followed met the increasingly stringent exhaust emissions standards. Like Volvo catalytic converters, catalyst material efficiency is reduced by tetraethyl or tetramthyl, thus cars and car systems with converters, like the Volvo catalytic converter, require unleaded fuel and nothing else.