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Two types of catalysis are generally distinguished. In homogeneous catalysis the reactants and catalyst are in the same phase. For example acids (H+ ion donors) are common catalysts in many aqueous reactions. In this case both the reactants and the catalysts are in the aqueous phase. In heterogeneous catalysis the catalyst is in a different phase than the reactants and products. Often in this case the catalyst is a solid and the reactants and products are gases or liquids. In order for the reaction to occur one or more of the reactants must diffuse to the catalyst surface and adsorb onto it. After reaction, the products must desorb from the surface and diffuse away from the solid surface. Frequently, this transport of reactants and products from one phase to another plays a dominant role in limiting the rate of reaction. Understanding these transport phenomena is an important area of heterogenous catalyst research. |
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Two types of catalysis are generally distinguished. In homogeneous catalysis the reactants and catalyst are in the same phase. For example acids (H+ ion donors) are common catalysts in many aqueous reactions. In this case both the reactants and the catalysts are in the aqueous phase. In heterogeneous catalysis the catalyst is in a different phase than the reactants and products. Usually, the catalyst is a solid and the reactants and products are gases or liquids. In order for the reaction to occur one or more of the reactants must diffuse to the catalyst surface and adsorb onto it. After reaction, the products must desorb from the surface and diffuse away from the solid surface. Frequently, this transport of reactants and products from one phase to another plays a dominant role in limiting the rate of reaction. Understanding these transport phenomena is an important area of heterogenous catalyst research. Important Catalytic Processes *The Haber process for ammonia synthesis *Steam Reforming of Hydrocarbons to produce [Synthesis gas]? *Methanol synthesis *[Fischer-Tropsch Synthesis]? *Hydrogenation/dehydrogenation of organic compounds *[Sulfuric acid]? production *Nitric acid production *Maleic Anhydride production *Petroleum refining and processing **Hydrotreating - hydrogenation of hydrocarbons and removal of organic sulfur, nitrogen, oxygen and metals **Catalytic cracking - breaking long-chain hydrocarbons into smaller pieces **Naptha Reforming **Alkylation *Industrial and automotive abatement of NOx, CO, and hydrocarbons *Nearly every chemical process associated with life! |
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