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What are Catalysts?

ENGS102P - Design and Professional Skills- Chemical Engineering Department- University College London Assignment 1: Explanatory Video Script: “Hi everyone! Today I’m going to be talking about catalysts. We use catalysts in engineering to speed up the rate of a reaction, and because they are not consumed during the process, we can actually use them over and over again. Some main examples in which catalysts are used today, are in catalytic converters, industry and CO2 capture and in food and wine processing. In general they reduce costs and they are better for our environment. For a Chemical reaction to occur, one of the main conditions is that the reactant particles must have a sufficient amount of energy to break their existing bonds. This minimum energy is actually called the Activation Energy. And so a catalyst provides an alternative route for a reaction to occur. And this alternative route has a lower activation energy. We can see this using a reaction profile diagram. So for the reactants to become the products they must have a sufficient amount of energy. Now without a catalyst this is much greater than with a catalyst. We can look at this further using a Maxwell- Boltzmann distribution graph. The area under the entire graphs is the total number of molecules in the reaction. The fraction of molecules having a given Kinetic energy is on the y axis, and the kinetic energy of those particles is in joules is on the x axis. And you can see that without a catalyst only a small number of molecules will react. However, with a lower activation energy, because of the catalyst, a larger number of molecules can then react. The reason why the activation energy is lowered is because the reactant molecules are adsorbed on the surface points of the catalyst called the active sites. When a molecule is adsorbed it creates a bond with the catalyst, weakening the bonds between the atoms in the molecules. So less energy is now needed to break the bonds between the atoms. I hope you have enjoyed my favorite part of A level Chemistry, and see you next time!”