Reduction Catalyst

The invention of the internal combustion engine goes back to the 17th century and earlier. It was a mere novelty at the time because there wasn’t any serious practical application for it due to the lack of a suitable fuel. It was the discovery of cheap oil sources and the invention, around the 1850s, of processes required to convert oil into easily-burning fuel that kick started the use of the internal combustion engine, transforming lives forever. In a span of just over a hundred years after the first automobile rolled off Henry Ford’s production line, the number of worldwide automobiles on the road crossed the one billion mark. This also means, unfortunately, that cars have become a significant emission of pollutants. The catalytic converter, first introduced into America in 1975, plays a significant role in the reduction of such pollution. What is a catalytic converter? How does it work? Can it be repaired? Read on to learn more about reduction catalysts.

What is a Catalyst?

When introduced into a chemical reaction, a catalyst appears to be a bystander because it isn’t consumed. However, it transforms the rate of the chemical reaction. Some enzyme catalysts in the human body increase the rate of reaction by a factor of well over 10,000.

What is Reduction?

Reduction occurs when a participant in a chemical reaction gains electrons. The partner in the process that has contributed these electrons is oxidised. For example, when carbon monoxide is converted to carbon dioxide, carbon is oxidised while oxygen is reduced.

How does a Catalytic Converter Reduce Emissions?

The modern three-way catalytic converter uses both oxidation and reduction to convert toxic byproducts of fuel combustion into relatively harmless compounds. The key pollutants that need to be dealt with are carbon monoxide, unused fuel, and nitrogen oxides. In catalytic converters, carbon monoxide and unburnt fuel are oxidised to produce carbon dioxide and water, while nitrogen oxides are reduced to oxygen and nitrogen.

What is the Structure of a Modern Catalytic Converter?

The key structures of a modern catalytic converter are the catalyst, the catalyst substrate, and the washcoat. A variety of metals can be used as catalysts, the most common being platinum, palladium, rhodium, and gold. The substrate is the basic structural framework on which the washcoat is applied. Most automobiles have a ceramic substrate. The washcoat, applied to the surface of the substrate, is what holds the catalyst in place, thus making it available for the catalytic reaction. Typical washcoats are made of silicon dioxide, aluminium oxide, or titanium dioxide.

What if a Catalytic Converter Fails?

A catalytic converter failure does not stop a car from running, but does dramatically increase its emission of pollutants. New cars in America require, by law, to have onboard diagnostics, like the OBD II, to monitor various systems of the car including the catalytic converter. Failure of a catalytic converter is usually reported on the car’s console. In addition, many jurisdictions in North America require periodic emission checks that independently evaluate emissions. Such emission tests diagnose a catalytic converter failure. Repair of a catalytic converter is generally not recommended.

America was the first country to legislate the use of the catalytic converter. These devices use basic reduction and oxidation reactions in the presence of catalysts to reduce the emission of toxic gases. If your car fails an emission test or onboard diagnostics reveal a problem with your converter, you are unlikely to be able to repair it. However, there’s a good chance that it is still under warranty because the typical catalytic converter is an extremely robust device.