3.5 PSA simulations
A simulated PSA process model was designed to evaluate the application potential of MIL-120Al in an industrial separation process. Using this model, the purity, recovery, and productivity of CH4 at different feed gas flow rates and/or adsorption times were investigated. Figure 7 shows the CH4 purity and productivity increases with an increase of in the feed gas flow rate. At the same time, a high gas flow rate leads to an increase in the amount of unabsorbed CH4, thus resulting in a decreased recovery rate. When setting the pass line for the CH4 recovery rate at 80%, the pristine 50% CH4 mixture can be enriched to 86% with a high productivity of 1.54 mol/h/Kg (Table S12). Such a high CH4 recovery and purity demonstrate that MIL-120Al has a good enrichment effect for the CH4/N2(50/50) mixture. As another important factor, the adsorption time was also considered in the simulation. An appropriate prolongation of the adsorption time was beneficial to increasing the recovery and productivity of CH4 (Table S13). For a 20/80 CH4/N2 inlet gas mixture, as shown in Figure S16, it can also achieve a 59% product gas concentration using this PSA method (Tables S10, S11). All of these results indicate that MIL-120Al has great application potential for CH4/N2 separation.