Evaluating the Performance of a Microporous Ti Bisphosphonate MOF for Postcombustion Carbon Capture by Vacuum Pressure Swing Adsorption.

A multiscale study was carried out to evaluate the microporous -Ti-bisphosphonate MIL-91-(Ti) sorbent for postcombustion CO capture in industrially relevant conditions. The process performance of the MOF was first assessed by using molecular simulated adsorption isotherms, which predicted an energy consumption of 1.65 MJ/kg and a productivity value of 0.42 mol/m. Subsequently, this Ti-MOF was characterized using several complementary experimental techniques, and the characterization data were supplied to a process simulator to assess energy consumption and productivity values for 95% purity and 90% recovery targets. The experimental adsorption isotherms resulted in a better process performance, with a minimum energy consumption of 1.03 MJ/kg and a maximum productivity of 0.61 mol/m. Such a discrepancy is likely to be due to the use of a generic force field that does not accurately capture host-guest intermolecular interactions in a highly confined environment of ultramicroporous MOFs like MIL-91. However, the lower energy consumption and higher productivity of this MOF, which are both desirable outcomes for CO capture processes, suggest the viability of MIL-91-(Ti) for implications in real CCS applications.