Modeling and simulation of a combined reactor/pressure swing adsorption unit for isomerization of a mixed feed of pentanes and hexanes

A novel process for isomerizing and separating n-pentane and n-hexane to their branched isomers is proposed. Both reactor and separation units are combined in one vessel. The vessel is divided into two sections: a reactor section and a PSA separation section. The reactor section is packed with Pt/Y-zeolite catalyst. The PSA separation section is equipped with a 5A zeolite adsorbent. A dispersed plug flow mathematical model of the entire process is developed using hydrogen purge. The model is used to investigate the dynamics of the PSAR units. For a constant molar feed containing equimolar fractions of 0.03 for each of n-C₅, n-C₆, i-C₅ and i-C ₆, the molar fractions of i-C₅ and i-C₆ rise to values of 0.0439 and 0.045 after reaching equilibrium conversion at the end of the reactor section. The PSA section allows for complete separation of n-C ₅ and n-C₆ from the reactor section effluent stream. Both 2D and 3D plots are reported as 2D plots are found insufficient to isolate all phenomena.