CHEMISTRY OF OLEFIN OLIGOMERIZATION OVER ZSM-5 CATALYST

Light olefins (C//3-C//6) can be converted to a mixture of higher molecular weight olefins via a sequence of acid-catalyzed-shape-selective polymerization and isomerization reactions over the ZSM-5 zeolite catalyst. The composition and molecular weight of the product are very dependent on reaction temperature and pressure through both thermodynamic and kinetic constraints. Distillate-range olefins having an almost petrochemical-type structure with high-quality fuel properties are produced at relatively high pressure (30-100-bar) and lower temperature (200-300 degree C) conditions. At lower pressure and higher temperature, lower molecular weight products are formed, including aromatics and saturates from olefin condensation and hydrogen-transfer reactions.