Catalytic Converters and Sustainability 

The use of fossil fuels in the transport sector has increased the greenhouse gas (GHG) emissions during the last decades. This is an issue of great concern towards global warming and climate change in the world. Fossil fuels used for transportation such as petrol or diesel release exhaust gases composed by carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), carbon monoxide (CO) and hydrofluorocarbons (HFCs).

These pollutants have adverse and irreversible impacts on both human health and the environment. Emissions from diesel engines compared to petrol engines are more hazardous and so it is a matter of major public concern. The harmful effects of fossil fuel emissions on the environment and human health have led to a number of scientific researches and inventions in order to reduce these vehicular exhaust emissions generated from the internal combustion engines. A Catalytic Converter is the most efficient device utilized in the exhaust system of a combustion engine in order to reduce exhaust emissions generated from combustion chemical reactions.

The issue of air pollution had been recognized as early as 1306 when King Edward I of England introduced a declaration prohibiting craftsmen from using sea-coal in their furnaces in an effort to improve air quality. During that time up until the invention of an automobile, the major contributor of air pollution was the burning of coal. A year after the introduction of the Ford Model T in 1908, scientists gave attention to the issue of noxious gases produced as a by-product of the internal combustion engine.

A Catalytic Converter is a large metallic box having a dense honeycomb structure inside it. It was designed by Eugene Houdry, a French mechanical engineer and expert in catalytic oil refining around 1950. After the results of early studies of smog done in Los Angeles were published, Eugene Houdry became concerned about the toll smokestack and automobile exhaust impacts on air quality and founded a company, Oxy-Catalyst.

Eugene Houdry first developed catalytic converters for smoke stacks called cats for short. Then he later developed catalytic converters for warehouse fork lifts that used low grade non-leaded petrol. Then in the mid-1950s he began his research to develop catalytic converters for petrol engines used on cars.

The biggest issue with combustion engines is that they tend to incompletely burn the fuel applied in them. Complete combustion is when the maximum amount of energy is being achieved, by the fuel being burnt, and it has two by-products; carbon dioxide and water. Incomplete combustion is when the maximum amount of energy is not achieved by the reacted fuel especially when there is too much fuel in the combustion mixture and insufficient relative oxygen present. To combat the creation of carbon monoxide during combustion, the catalytic converter was implemented. The catalytic converter has two chambers namely, the reduction and oxidation chambers. The first chamber consists of Platinum and Rhodium coated ceramic honeycomb structures, which reduces the nitrous oxide (NO_x) emissions by acting as a reduction catalyst. Exhaust gasses flow through the other chamber formed by Platinum and Palladium, which acts as an oxidizing catalyst. In this chamber, disintegration of hydrocarbons (HC) and the formation of carbon dioxide (CO₂) takes place with the extra oxygen (O₂) in the presence of catalysts. Scientific studies discovered that catalytic converters decrease hydrocarbons by 87%, carbon monoxide by 85%, and nitrous oxide by 62% depending on the life cycle of a vehicle. Apart from removing noxious chemicals and pollution from car emissions as a result of fossil fuel combustion, the catalytic converter helps the overall engine efficiency.

A growing concern regarding the effects of vehicle exhaust emissions on human health and natural ecosystems is causing serious consideration to be given towards requiring all new vehicles to have catalytic converters fitted in their exhausts. The development of sustainable catalytic converters still remains a critical issue due to the stringent exhaust emission regulations. While catalytic conversion of gaseous small molecules in tailpipe emissions currently draws significant public attention, catalytic gas conversion has been an important industrial process for years. Taking advantage of the catalytic converters’ invention, some companies have been converting atmospheric nitrogen gas into other nitrogen-rich compounds used for fertilizers, cleaners, refrigerants, explosives and much more. At the turn of the 20^th century, other industries and manufacturing companies used an extremely energy-intensive non-catalytic process for converting nitrogen and oxygen gases to nitric acid, which eventually was replaced by an alternative catalytic process.

Catalytic converters were invented to decrease pollution. However, catalytic converters only reduce harmful gasses. They do not completely remove toxins from the combustion engine emissions. Also, catalytic converters work best in high temperatures. The main by-product of a catalytic converter process is carbon dioxide which has recently been found to be one of the biggest contributors to global warming and climate change.

The catalytic converter fulfilled its purpose in greatly reducing the levels of smog and air pollution generated in car-dense environments, and as a result, it will go down in history as one of the most effective automotive advancements of all time. With that being said, the modern world cannot rely on the catalytic converter as a complete solution for the negative impacts of internal combustion engines on our environment. Hence, better and more sustainable solutions are needed.