Catalytic Converter Catalytic Converter Catalytic Converter

about us
converter design
converter faq
converter failure
converter care
nox emissions
aftermarket converter
converter obd II
converter us law
converter links
converter news
converter replacement
site index
contact us

Discount Catalytic Converter
Catalytic Converter

Please support our site's generous sponsors.

Catalytic Converter
dot org
Contact Us

Catalytic Converter

Catalytic Converter Design

Passenger vehicle manufacturers have made tremendous progress in reducing emissions since the introduction of the first automotive catalytic converter in the mid-1970s. Early converters, called "two-way" converters, burned a percentage of the unused hydrocarbons (HC) and carbon monoxide (CO) produced by the relatively inefficient, low compression engines of the day.

Two-way (oxidizing) converters burn HC and CO molecules with the assistance of a precious-metals catalyst. This process "converts" these harmful gasses into water vapor and carbon dioxide (CO2). It's important to understand that two-way converters are most effective when used with engines that have a lean air/fuel mix because this condition provides ample oxygen to "burn" the pollutants.

Three-way converters use two catalyst processes — reduction and oxidation —- and a sophisticated oxygen storage/engine control system to convert three harmful gasses - HC, CO and oxides of nitrogen (NOx). This is not an easy task: the catalyst chemistry required to clean up NOx is most effective with a rich air/fuel mix, whereas HC and CO reduction are most effective with a lean air/fuel bias. To operate properly, therefore, a three-way converter first must convert NOx (with a rich air/fuel bias), then HC and CO (with a lean bias).

Older three-way converters, called "three-way with air" or "three-way plus oxidation," perform this process by introducing additional oxygen between the reduction and oxidation stages to create a lean condition for the oxidation catalyst. (These converters are easily identified by their air tube.)

Modern three-way units, found on most vehicles manufactured since the late 1980s, rely on an advanced catalyst chemistry that stores and releases oxygen on a single substrate, and an oxygen monitoring and control system (utilizing one or more O2 sensors) that causes the engine to oscillate between lean and rich conditions. This oscillation, combined with the oxygen storage and release on the catalyst surface, enables the unit to convert all three harmful gasses with the same catalyst brick.

Today's "three-way" OBD II converters are just the last step in a highly sophisticated emissions control process. The chief component of this system is the engine itself, which, when operating properly, is significantly more efficient — and environmentally friendly — than its 1970s and 80s counterparts. Other leading components and systems playing important roles in reducing emissions in today's vehicles are engine sensors/controls, improved combustion chamber design and electronic fuel injection technology, each of which enhance the efficiency of the combustion process, resulting in fewer unburned pollutants.


home | catalytic converter care | about us | e-mail

ImageBuilders Web DesignCopyright 2020 ImageBuilders Web Design


Catalytic Converter Warehouse
Catalytic Converter

Please support our site's generous sponsors.

Catalytic Converter
Catalytic Converters dramatically reduce harmful exhaust emissions

Catalytic Converter
Catalytic converters typically consist of a ceramic or metal honeycombed monolith substrate that carries precious metal catalysts.