催化剂

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催化剂(catalyst)

化学术语，能增加反应速率而其本身并不消耗的一种物质（参阅catalysis）。一个催化剂分子可在一分钟内转化成好几百万个反应物分子。气态、液态和固态的催化剂可能是无机化合物、有机化合物，或是复杂的化合物。通常，催化作用是催化剂与一种反应物之间进行化学反应，生成一些中间化合物，它们互相之间或与另一反应物以更快的速度反应，生成所需最终产物。在中间化合物和反应物进行反应的过程中，催化剂一般能够再生。催化剂和反应物之间的反应方式很不相同，使用固体催化剂时更为复杂。典型的催化反应有︰酸－硷反应，氧化－还原反应，生成配位错合物和生成自由基的反应。来自反应物或反应本身产生的物质会抑制（降低）催化剂的效能。催化剂对所有的工业化学反应非常重要，特别是在提炼原油和合成有机化学制造方面。大部分的固体催化剂是细粒状过渡元素（金属）或它们的氧化物。在汽车的催化转换器中，铂催化剂把未能燃烧掉的烃和氮化合物转化成不会对环境造成伤害的产物。水（特别是盐水）会促进氧化和腐蚀。是已知最活跃和最易被挑选的催化剂。

English version：

catalyst

Any substance of which a small proportion notably affects the reaction rate of a chemical reaction without itself being changed or consumed (see catalysis). One molecule may transform several million reactant molecules a minute. Gaseous, liquid, or solid, catalysts may be inorganic compounds, organic compounds, or complex combinations. They tend to be highly specific, reacting with only one substance or a small set of substances. Substances that alter them or block reactants' access to them may inhibit (poison) them. Catalysts are essential to virtually all industrial chemical reactions, especially in petroleum refining and synthetic organic chemical manufacturing. Most solid catalysts are fine-grained transition elements (metals) or their oxides. In a car's catalytic converter, the platinum catalyst converts unburned hydrocarbons and nitrogen compounds to products harmless to the environment. Water, especially salt water, catalyzes oxidation (see oxidation-reduction) and corrosion. Enzymes are among the most active and selective catalysts known.

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