Thermodynamic Analysis on Isomerization of n-Pentane to Isopentane

The thermodynamic behaviors of n-pentane isomerization to isopentane were systematically analyzed using SRK equation, and thermodynamic data, phase state, equilibrium composition and equilibrium isomerization ratio of n-pentane under different reaction conditions were calculated. The results show that the reaction is exothermic and decreasing the reaction temperature favors the increasing of equilibrium isomerization ratio of n-pentane. When the reaction temperature is high (e.g. moderate temperature zeolite-based isomerization or solid superacid isomerization), the reaction system is gas phase and similar to ideal gas. Therefore, the effects of reaction pressure and molar ratio of hydrogen to hydrocarbon (n(H2)/n(HC)) on equilibrium isomerization ratio of n-pentane are insignificant. At low reaction temperature (e.g. low temperature isomerization), the reaction system is gas phase or gas-liquid two-phase and shows nonideality. As a result, the influence of reaction pressure and n(H2)/n(HC) on the reaction should not be neglected. The equilibrium isomerization ratio of n-pentane can be increased by decreasing the reaction pressure or increasing n(H2)/n(HC). © 2020, Editorial Office of Acta Petrolei Sinica(Petroleum Processing Section). All right reserved.