Novel Application of Partially Positively Charged Silver Nanoparticles for Facilitated Transport in Olefin/Paraffin Separation Membranes

The interactions between BF4− ions (from the ionic liquid BMIM+BF4−) and the surfaces of silver nanoparticles caused the Ag surfaces to be partially positively charged, resulting in increased activity in silver−olefin complexation. The surface positive charge was confirmed by the increase in binding energy of the d5/2 orbital of the silver nanoparticles from 368.26 to 369.12 eV as the silver content increased. The surface positive charge and consequent enhancement in olefin complexation ability were exploited through the use of silver nanoparticles as a new type of olefin carrier for facilitated transport. As a result, membranes containing BMIM+BF4−/Ag nanoparticles demonstrated a mixed-gas selectivity of 17 for a 50/50 (vol %) propylene/propane mixture and showed stable performance for 100 h.