Also known as the catalyst, one can change the speed of chemical reactions in the material itself is not consumed in the reaction. Their role is usually to speed up the reaction, such as iron catalyst makes nitrogen into ammonia and hydrogen reaction is greatly accelerated, and makes it possible to ammonia industry. If its role is to slow the reaction is called negative catalysts, such as a small amount of alcohol, phenols or sugar inhibits sodium sulphite solution is oxidized by the oxygen dissolved in the water. Catalyst is a gaseous substance (nitrogen dioxide), liquid substances (such as acids, alkali, salt solutions) or solid materials (such as metals, metal oxides), and some exist in colloidal State (such as bio-enzyme). Catalyst industries, the main product is a solid catalyst. Performance a catalyst can be made less specific reactions through resistance of channels to reduce the activation energy required, so that the reaction speed. Dotted line in the figure represents reactants through non-catalytic reaction pathways into products, activation energy for the e.