Catalyst is a term used to refer to any element that fastens the rate at which a reaction takes place without getting consumed. A catalyst can either be synthetic, metallic or organic. Enzymes are catalysts that occur naturally and are responsible for numerous important biochemical reactions. Many catalysts that are in solid form are metals or oxides, halides and sulfides if metallic substances as well as of semi-metallic substances such as aluminum, boron and silicon. Catalysts that occur in liquid and gas form are mostly used along with suitable solvents or carriers or in their absolute form. On the other hand, catalysts that have a solid form are usually dispersed into other elements referred to as catalyst supports. The process through which an element increases or reduces the rate of reaction is known as catalysis. Activation energy is necessary for any reaction to occur. In the absence of a catalyst, the energy required to spark off a reaction is extremely high.
The reaction that results between a reactant and a catalyst is known as a catalytic action. A catalytic action results to the formation of chemical intermediates that cannot readily react with each other or with other reactants resulting to an end product. As the reaction between a reactant and a chemical intermediate happens, a catalyst becomes regenerated. The mode of reaction that happens between reactants and catalysts varies widely and is usually complex in catalysts that are solid. Reactions involving acid base, coordination complex and free radical formation as well as oxidation are examples of reactions that are typically complex. Reactions involving solid catalysts are heavily influenced by electronic and surface properties as well as crystal structures. Some solid catalysts known as polyfunctional can handle multiple interactions with reactants while bifunctional catalysts are extensively used to reform reactions in petroleum industries. Catalytic reactions are the basis of numerous chemical processes in industries. The manufacture of catalysts is a fast developing industrial process.