Redox Catalyst Essay

991 Words 4 Pages
1. Redox Catalyst
Catalyst is defined as a substance that increases the rate of a chemical reaction without changing its chemical composition and affecting the standard Gibbs free energy, by lowering the activation energy of a chemical reaction. It does so by providing an alternative reaction pathway. In redox reaction, the key chemical event is the net movement of electrons from one reactant to the other. The oxidation state of atoms are changed. Transition metal is used as redox catalyst due to the availability of empty d-orbitals and the ability to change its oxidation state. Transition metal ions with different oxidation state have different electronic configurations. This allow them to interact in a specific fashion with different organic
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The catalytic converter system in vehicle exhaust tried to eliminate nitrogen oxide emissions, carbon monoxide emissions and hydrocarbon emissions which is unburned fuels. In a catalytic converter has two blocks which is reduction catalyst and oxidation catalyst. The reduction catalyst is made up of platinum and rhodium while the oxidation catalyst is made up of platinum and palladium. During combustion, the toxic gas enter into the first catalytic converter and heat up simultaneously. This causes the catalyst to react with the toxic gases. First step is eliminate nitrogen oxide to nitrogen and oxygen on the surface of reduction catalyst. This phenomena is explained as the nitrogen bond with the oxygen is not as strong as its bond with catalyst. When it bond with the catalyst, it will weaken its bond with oxygen. The next step is going through the oxidation catalyst. Carbon monoxide and oxygen molecules will bond on the surface of the catalyst. Once oxygen molecules bond on the surface, it will split up and the bond with carbon monoxide is stronger. This will produce carbon dioxide. The bond between carbon dioxide and the bottom of catalyst is weaken and release carbon dioxide. The free oxygen will combine with unburned hydrocarbon to form water and carbon dioxide. When the exhaust is heated up, the catalysis reaction can occur more easily. Unleaded fuel is used in catalytic converter because the lead in conventional fuel "poisons" the catalyst and prevents it from taking up the pollutants in exhaust

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