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Catalysing for success This presentation will discuss what catalysts are, their mechanisms of action and their significance to the chemical industry. Introduction

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Catalysis-catalysing for success Catalysing for success This presentation will discuss what catalysts are, their mechanisms of action and their significance to the chemical industry. Introduction Catalysis is a remarkable phenomenon. Quite apart from the scientific reality, the financial and environmental benefits of harnessing its power are very impressive. Catalysts in definition developed by scientists in the last century, are materials that change the rate of attainment of equilibrium without themselves being changed or consumed in the process. To illustrate the importance of catalysis, here are some of the many applications of it: Chemical and materials manufacturing, Fuel cells, Combustion devices, Pollution control systems, Laundry detergents. The mechanisms of catalytic action in some of the above applications will be discussed later. Types of Catalyst There are two types of catalyst: Industrial catalysts - These are non-biological catalysts, which include solid state, finely separated metals (particularly rare earth metals such as platinum, palladium, iridium etc) or one of many compounds known to possess catalytic activity. Biological catalysts- These are complex proteins that possess catalytic activity. They are commonly referred to as enzymes. These are derived from living sources and will be discussed later. Mechanisms of catalytic action in the Harber process? Catalysts work by changing the activation energy (Eact) for a reaction, i.e. the minimum energy needed for the reaction to occur. This is accomplished by providing a new mechanism or reaction path through which the reaction can proceed. ...read more.


With homogeneous catalysts it is recognised that there are costs and time involved when separating the homogeneous catalyst from the product. This is the reason why homogeneous catalysts are usually reserved for highly selective and complex reactions, especially in pharmaceutical manufacture. Familiar Uses of catalysts Some familiar uses of heterogeneous catalysts include: Platinum and other rare earth metals in catalytic converters Here the extremely finely divided metal surface (arranged as a honeycomb) acts as a reaction site for noxious gases that are emitted from the exhaust. For example the following reaction between carbon monoxide and nitrogen monoxide: 2CO + 2NO Platinum Catalyst 2CO2 + N2 is far too slow in uncatalysed conditions resulting in high emissions of the toxic carbon and nitrogen monoxides; this would also result in failing an M.O.T. test, when testing for emission percentages. With the platinum blend catalyst, the reaction is rapid, with harmless carbon dioxide and nitrogen gas being the catalytic reaction products. Biological catalysts - Enzymes Enzymes belong to a specific group of proteins that are synthesised by living cells. They function as catalysts for the large number of biochemical reactions that constitute the metabolism of a cell and indeed a living organism. Mechanism of Enzyme Action Again enzymes function on the principle of catalysis, they reduce the activation energy of metabolic reactions in cells. There are a number of mechanisms by which this activation energy decrease may be achieved. ...read more.


Summary Of Presentation In this presentation we have learned about the many applications of catalysis. Catalysts both biological and non-biological, work on the same principle. They reduce the activation energy (Eact) of a reaction, resulting in the attainment of equilibrium much faster. Catalysts can be divided into two types Industrial (non-biological) catalysts - These include finely divided metals, specific compounds designated for certain reactions. Biological catalysts (enzymes) are complex proteins, derived from living cells. These are employed in detergents, pharmaceuticals and pharmaceutical manufacture. Enzymes can be irreversibly damaged by extremes of temperature and pH Catalysts can be categorised again; depending on the state they are when they are catalysing a reaction. Heterogeneous catalysts are in a different phase to the reacting species, whilst homogeneous catalysts are in the same phase as the reacting species. Heterogeneous catalysts are generally the most used in industry as they are the most resistant to poisoning Homogeneous catalysts are reserved usually for complex reactions requiring catalysts with high selectivity for certain reagents i.e. in pharmaceutical drug manufacture. Everyday applications for catalysts include use in catalytic converters and biological washing powders. Catalysis is a valuable technology that has enabled us to get the most from chemical and petroleum resources. Costs, which are reduced by catalysis, are passed on to us, for example the anti - inflammatory drug cost 60 a gram in the 50's-60's. With the introduction of better synthesis routes and better catalysts, the cost of cortisone has been reduced to around 50 pence a gram. ...read more.

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