Olefin is a kind of hydrocarbon with double bond structure, such as ethylene and propylene. Because of its special molecular structure, olefin products have a wide range of uses. In the chemical field, olefin products are used as basic raw materials for manufacturing plastics, rubber, fibers and coatings. Ethylene is widely used to produce polyethylene (PE), a common plastic material. Propylene is used to make important chemicals, such as polypropylene (PP) and acrylic acid. Olefins can also be polymerized to prepare various polymers, such as polyvinyl alcohol and polypropylene alcohol. In the energy field, olefin products also play an important role. Ethylene can be used to make synthetic rubber and synthetic fiber, and it is also an important raw material for petrochemical industry. Propylene can be used to make fuel additives and solvents.