Pollutants have scattered the globe causing much damage to the ecosystem. One leading soucre of pollution is found in the very air we breath. Most of the time, air pollution is caused by the millions of cars all over the world. That is why automakers have not stopped in developing new technologies that will really help the environment, one of which is producing catalytic converters.
In the case of the VW catalytic converter, it is a device used to reduce the toxicity of emissions from an internal combustion engine. In order to reduce emissions, modern car engines carefully control the amount of fuel they burn. They try to keep the air-to-fuel ratio very close to the calculated ideal ratio of air to fuel called, stoichiometric point. The main emissions of a car engine are nitrogen gas, carbon dioxide and water vapor. These emissions are mostly benign. But because the combustion process is never perfect, some smaller amounts of more harmful emissions are also produced in car engines. These are carbon monoxide, hydrocarbons or volatile organic compounds (VOCs) which is produced mostly from unburned fuel that evaporates. Another harmful compound is nitrogen oxide (NOx), which contributes to smog and acid rain, and also causes irritation to human mucus membranes. These are the three main regulated emissions and also the ones that VW catalytic converters are designed to reduce.
Most modern cars are equipped with three-way catalytic converters. It refers to the three regulated emissions it helps to reduce which are carbon monoxide, VOCs and NOx molecules. The converter uses two different types of catalysts, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, which is usually platinum, rhodium or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream while also minimizing the amount of catalyst required. There are two main types of structures used in catalytic converters, honeycomb and ceramic beads. Most cars today use a honeycomb structure.
The VW catalytic converter do their job in three stages. The first stage is the reduction catalyst. It uses platinum and rhodium to help reduce the NOx emissions. When a nitrogen oxide molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. The oxidation catalyst is the second stage of the VW catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. The final stage is a control system that monitors the exhaust stream and uses this information to control the fuel injection system. There is an oxygen sensor mounted upstream of the VW catalytic converter, meaning it is closer to the engine than the converter is. This sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can increase or decrease the amount of oxygen in the exhaust by adjusting the air-to-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point. It also make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO.
Today's technology is also being tapped to help the environment. Like the that have proved to be helpful. Since automakers nowadays have realized technology's limitless potential and their responsibility to the environment, they have also turned to producing hybrid cars.
