Patent ID: 8648227

Claim:
A process for the production of colorless styrene of polymerization grade from a pyrolysis gasoline fraction containing C 7 −, C 8 and C 9+ hydrocarbons, wherein the C 7 −hydrocarbons include cyclopentadiene chromophores and wherein the C 8 hydrocarbons include phenylacetylene, by fractional and extractive distillation, which consists essentially of the steps of: (a) fractionally distilling the pyrolysis gasoline fraction containing C 7 −, C 8 and C 9+ hydrocarbons, in a divided-wall column having a top, a center and a bottom, at a temperature too low for the cyclopentadiene chromophores to undergo a Diels-Alder reaction with olefins to form Diels-Alder products in which the cyclopentadiene chromophores are masked by olefins, but which can decompose into the initial reactants, to obtain at the top a C 7 − hydrocarbon fraction including cyclopentadiene chromophores, to obtain at the center a C 8 core hydrocarbon fraction including styrene and phenylacetylene, said C 8 core hydrocarbon fraction free of the cyclopentadiene chromophores masked by olefins, and to obtain at the bottom a C 9+ hydrocarbon fraction; (b) selectively hydrogenating phenylacetylene within the C 8 core hydrocarbon fraction; and following step (b); (c) extractively distilling the C 8 core hydrocarbon fraction to extract a colorless styrene of polymerization grade fraction and a fraction poor in styrene, wherein steps (a), (b) and (c) are the only required steps carried out to obtain the colorless styrene of polymerization grade from the pyrolysis gasoline fraction.