Catalytic Converter: Description and Operation

Typical Exhaust Configuration:

DESCRIPTION
The catalytic converter is an emission control device added to the exhaust system to effectively reduce the levels of carbon monoxide, hydrocarbons, and in some cases oxides of nitrogen, exiting the tailpipe. The converter contains catalysts that promote oxidation of residual hydrocarbons and carbon monoxide.

More recently, converters contain an additional catalyst that also promotes reduction of oxides of nitrogen emissions. These type converters are referred to as "Three-Way Catalytic converters. Three-Way converters reduce oxides of nitrogen compounds into their constituent elements, oxygen and nitrogen gas. The oxygen released in the reduction of NOx is then consumed in the oxidation reactions with the remaining HC and CO in the exhaust.

Catalytic Converter Cut-away:

The Corvette uses two single bed monolithic "three-way" catalytic converters. Inside each converter is a porous monolithic (one piece) honeycomb substrate made of ceramic material. This substrate material is impregnated with the catalytic elements platinum, palladium, and rhodium. When heated, these elements promote oxidation of hydrocarbons (HC) and carbon monoxide (CO), and reduction of oxides of nitrogen (NOx), by taking part in an intermediate chemical reaction that leaves the catalysts unchanged.

NOTE: Use of leaded fuels, or fuel additives containing lead contaminates the catalyst, rendering the catalyst ineffective. Use only unleaded fuels on catalytic converter equipped vehicles. A small diameter fuel tank filler is used on catalytic converter equipped vehicles to prevent the introduction of leaded fuel from the larger diameter leaded fuel pump nozzles.

Because of the high temperatures generated within the converter, heat shields are necessary to protect chassis components, passenger compartment, and other areas from heat related damage.

CAUTION: Prolonged operation with a misfiring or flooded engine may cause the converter to overheat. This creates a fire hazard and could cause damage either to the catalyst itself or the vehicle, and possible personal injury. Also, when jacking or lifting vehicle from frame side rails, be certain lift pads do not contact catalytic converter otherwise damage to converter may result.