The catalyst can change the reaction rate in the chemical reaction, and the composition and the quality of the catalyst can be kept constant after the reaction. The catalyst that accelerates the reaction is called the positive catalyst, slows down called Negative Catalyst or slow agent. It said catalyst is a positive catalyst for the general correction. This kind of catalyst in the industry, especially the organic chemical industry used more, and has great significance, Such as sulfuric acid prepared by contacting, ammonia, hydrolysis of the ester and polysaccharide, Oil Hydrogenation, etc. Commonly used catalysts are mainly metal, metal oxide and inorganic acid. If the catalyst is solid, the substance of the reaction is gas, to form a multi-phase catalytic reaction, this catalyst, sometimes called catalyst or contact agent. The catalyst is generally selective, it can only make a reaction or a certain type of reaction to speed up. But some reaction can be used for a variety of catalysts, such as the hydrogenation reaction can often be platinum, palladium, nickel, should be carefully chosen. In the catalytic reaction, the catalyst is often added cocatalyst known to enhance catalytic action of the catalyst. For example, iron is a catalyst in ammonia industry, adding a small amount of potassium and aluminum can enhance the catalytic effect of iron. The composition and weight of the catalyst and cocatalyst cannot change before and after the reaction. All of the above are inorganic catalysts. The enzyme is a protein, is very important organic catalyst. There are many kinds of catalyst, catalyst and reaction system according to the phase of the classification, there are two types of homogeneous and heterogeneous catalysts. Heterogeneous catalysts most widely used, there are 3 kinds of gas, liquid and solid state, the variety and application of solid catalyst. The solid catalyst, which is made of metal (nickel, platinum, palladium, chromium, cobalt, titanium, va