CATALYST

• Product Name:CATALYST
• Synonyms: NAFION SUPER ACID CATALYST CATALYST JB-4 PLUS CATALYST JB-4 CATALYST
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• MW:0
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• Mol File:Mol File
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A catalyst is a substance which, in small quantities, facilitates a reaction or favorably alters the rate of a chemical reaction, without itself undergoing any permanent chemical change. This phenomenon is called catalysis. Acid-based catalysis is an important type of catalysis.<br/> Catalysts that have the same phase as the reactants are known as homogeneous catalysts while those having a different phase are called heterogeneous catalysts. Generally, a catalyst that increases the reaction rate is known as a positive catalyst while one that slows down the rate is known as a negative catalyst, retardant or inhibitor.<br/> Some examples of catalysts and their roles are as follows: (i) Protein catalysts, called enzymes, speed up many chemical reactions in living organisms. These play a key role in all metabolic or biological processes and in some manufacturing processes, such as the fermentation industry. (ii) Catalytic converters, in automobiles, employ a mixed oxide bed over which the exhaust gases pass after they are mixed with additional air. These catalysts promote oxidation of carbon monoxide and hydrocarbons to carbon dioxide and water.<br/> Catalysts may be inorganic, organic or complexes of organic groups and metal halides. (Zeigler-Natta cataIysts). They may be gases, liquids or solids. In some cases, their action is undesirable and destructive, as in the oxidation of iron to iron oxide, which is catalyzed by water vapor (rusting). The life of an industrial catalyst varies from 1000 to 10,000 hours, after which it must be replaced.<br/> Catalysts are highly specific in their action and application and very essential for many industrial chemical reactions, as in petroleum refining and organic syntheses. The activity of a solid catalyst is centerd in a small fraction of its surface; adding promoters increases the surface area by increasing the porosity or the number of active points. Substances that act as poisons clog and weaken the catalyst surface, thus decreasing the catalytic activity.