Solid state facilitated transport membranes with higher olefin selectivity were prepared using silver nanoparticles activated by electron acceptors, such as p-benzoquinone (pBQ) as olefin carriers and inert poly(ethylene co-propylene) (EPR) polymer matrix. Here, the effect of pBQ in silver-polymer nanocomposite membranes on the dispersion of silver nanoparticles on the polymer matrix and the structural properties of the membranes were investigated and correlated with the facilitated olefin transport. Transmission electron microscopy (TEM) and photographs clearly showed that pBQ plays an effective role as a stabilizing agent, resulting in a good dispersion of the silver nanoparticles in the EPR matrix. The good dispersion by pBQ was attributed to the strong interaction between pBQ and silver nanoparticles, as confirmed by x-ray photoelectron spectroscopy (XPS). Differential scanning calorimetry (DSC) also showed that the increased propylene permeance by pBQ was not caused by the increased chain flexibility of the membranes but facilitated olefin transport due to a reversible interaction between the olefin and silver nanoparticles.