Propylene/Nitrogen Separation in a By-Stream of the Polypropylene Production: From Pilot Test and Model Validation to Industrial Scale Process Design and Optimization

Abstract

Two industrial-scale pressure swing adsorption (PSA) processes were designed and optimized by simulations: recovery of only nitrogen and recovery of both nitrogen and propylene from a polypropylene manufacture purge gas stream. MIL-100­(Fe) granulates were used as adsorbent. The mathematical model employed in the simulations was verified by a PSA experiment. The effect of several operating parameters on the performance of the proposed PSA processes was investigated. For the nitrogen recovery, a 5-step 2-column PSA process produced a nitrogen stream of 95.4% purity with recovery of 85.2%, productivity of 6.0 mol N₂/kg adsorbent/h, and power consumption of 156 Wh/kgN₂. Nitrogen and propylene with 96.2% and 97.6% purity, respectively, were obtained from the 6-step 3-column nitrogen and propylene recovery PSA process. The nitrogen and propylene recoveries obtained are 98.4% and 91.0%, respectively. The nitrogen and propylene productivities were estimated as 4.61 and 1.83 mol product/kg adsorbent/h and the power consumption as 383 Wh/kgN₂