WHAT IS A CATALYST?
a definition ...
an agent that changes (either increasing or decreasing) the rate of a chemical reaction.
- Catalysts change the kinetics of one or more reactions without being transformed.
- Catalysts save energy, time, and or expense, which is why they are useful.
- A catalyst is a substance that increases or decreases the rate, or speed, of a reaction, at some temperature, without itself being transformed. A catalyst does this by reducing the energy needed for the reaction to occur, thus saving energy, time and money.
A good example of a catalyst is the catalytic converter in our cars and trucks, which speeds up combustion reactions between unburned hydrocarbons and carbon monoxide with oxygen to form carbon dioxide and water; and also the reaction between nitrogen oxides and carbon monoxide to form carbon dioxide and nitrogen. The catalyst in this case is usually platinum, palladium and rhodium metals deposited on a high surface area aluminium oxide. These expensive noble metals do not change as they act as catalysts, but the device slowly becomes less effective with use because products of combustion physically cover the active metals and because the carrier aluminium oxide looses surface area.
Without the catalytic converter, the noxious compounds react too slowly with each other and oxygen so that they will exit the tail pipe and enter our environment. These spontaneous reactions occur much faster in the presence of the catalysts at exhaust gas temperatures. The exact mechanisms of the catalysts in a converter in some of these reactions is still not known in spite of the fact that they have been on vehicles commercially since 1975, and tested on buses in Washington, D.C. as early as 1953 by the W.R. Grace Co.
There are two types of catalysts, heterogeneous and homogeneous. If the catalyst is a gas that operates on a gas, it is homogeneous. If the catalytic converter is a solid that operates on a gas, it is a heterogeneous catalyst. As the Fitch Fuel Catalyst (FFC) is a solid that operates on a gas or a liquid, it is classed as a heterogeneous catalyst.