Catalyst exhausts

The catalyst exhaust is a device installed on an internal-combustion engine exhaust system, normally between the engine and the original silencer. The catalyst exhaust is able to cut the emission of pollutants contained in engine exhaust gases, such as carbon oxides and hydrocarbons. The operating principle behind the catalyst exhaust is based on the transformation of such polluting substances into water and carbon dioxide. The catalyst exhaust normally consists of a steel casing containing a honeycomb support on which a noble metal (Platinum, Palladium and Rhodium) is deposited by impregnation and subsequently oven baked in very specific quantities. The honeycomb support therefore represents the heart of the catalyst exhaust and can be made of ceramic or metal. In the past, only ceramic supports were used, but in recent years, these have been almost entirely replaced by metal supports, which are stronger, provide better performance and are much smaller in size. In order for the catalyst exhaust to start operating and reach a high efficiency in terms of cutting pollutant emissions, the exhaust gases must reach a temperature of at least 280°C. Thanks to their small size, catalyst exhausts can now not only be fitted to cars and motorcycles but also to industrial vehicles such as: fork-lift trucks, power generators, trucks, excavators and operating machines in general. The catalyst exhaust is generally fitted to diesel engines but can also be fitted to lead-free petrol engines (meaning without lead-based compounds which would poison the catalyst). The size of the catalyst exhaust is normally tied to the power of the engine, to the displacement and to the amount of exhaust gases; the type and the quantity of noble metal are on the other hand defined according to the different polluting substance reduction requirements and engine operating conditions. Thanks to the introduction of the catalyst exhaust, a big step forward has been taken in cutting atmospheric pollution and working conditions have improved considerably in closed environments such as tunnels, mines and warehouses.