Catalysts speed up the rate of reaction and remain chemically unchanged or being used up in the process, and are widely used in industry. Enzymes are biological catalysts made up of proteins, and can be used a lot in industry since they operate best close to room temperature and pressure which can be maintained in industrial processes. Catalysts will speed up rate of reaction and can also be used to change properties of a product to increase it’s usefulness – it can turn light, bendy poly(ethene) into a more dense and less flexible material with a higher melting point.
An example of an enzyme used as a catalyst is during the production of ethanol. Ethanol is the alcohol people drink and is also used as a fuel, solvents and as a feedstock for other processes. Fermentation uses the enzyme zymase which is an enzyme used in fermentation of the breakdown of sugar into ethanol and carbon dioxide. Zymase is naturally occurring tin yeast when making alcohol as it breaks down sugars into ethanol with carbon dioxide as a by-product:
This is efficient under controlled conditions such as temperature (30˚C). Although the method of making ethanol is renewable since sugar beets and yeast grow fast, the reaction has low atom economy and the enzyme gets killed from the ethanol produced. However, the industrial production of ethanol is also a good example of why Le Chatalier’s principle is important in real life as ethanol is produced by a reversible reaction between ethene and steam.
Iron is used as a catalyst in the Haber process – the reversible production of ammonia, which combines hydrogen and nitrogen. Containing potassium hydroxide as a promoter to increase it’s efficiency, the use of iron does not make it necessary for the use excess heat energy needed to raise the temperature high enough to make the reaction happen quick enough, which would raise fuel bills and also result in less amount of ammonia reduced. Iron is an efficient catalyst in the production of ammonia as it increases output of the desired product and, like all catalysts, does not get used up in the reaction. Catalysts also aid in reducing the number of steps a product can be made, for example, the painkiller ibuprofen traditionally takes 6 steps with an atom economy of 32%. Using catalysts during it’s production, only 3 steps are taken resulting in an atom economy of 77%.
Another use of catalysts in industrial methods is making esters. Esters are a compound made from carboxylic acids and alcohol, resulting in artificial fragrances found in cosmetics. The reaction forming esters is reversible so some of the ester formed will react with water and reform the carboxylic acid and alcohol. To make ethyl Ethanoate, for example, concentrated sulphuric acid (the catalyst) is used to accelerate the speed of reaction, done during the refluxing stage.
Human activity is changing the atmosphere by adding small amounts of pollutants into the atmosphere from sources such as particulates and...