Cracking C5 fractions are by-products in ethylene manufacturing process of steam cracking. Most C5 fractions are reactive and thus can be uesd to produce value –added products. The mono-olefins and diolefins from the C5 fractions can be used to product many fine petrochemical products such as isoprene rubber, thermoplastic elastomer, butyl rubber, ethylene propylene rubber (EPDM), petroleum resin, unsaturated polyester, epoxy resin curing agent, various additives, pesticide intermediate, medicament intermediate and perfume.
The content of isoprene (ISP), cyclopentadiene (CPD, usually existing in the form of dimmer, dicyclopentadiene) and piperylene (PIP) with high value in the C5 fractions is 45%-55%, other components are isopentene, 1-pentene, n-pentane, isopentane and cyclopentane. The boiling points and relative volatilities of these fractions are similar, and azeotropes are formed easily. These fractions are difficult to separate. However, the application value of these products can be embodied only by separation with high purity.