CO2Transport in Polysulfone Membranes Containing Zeolitic Imidazolate Frameworks As Determined by Permeation and PFG NMR Techniques

Abstract

This work describes the preparation of mixed matrix membranes by casting from poly(1,4-phenylene ether−ether−sulfone) chloroform solutions containing dispersed zeolitic imidazolate frameworks. Diffusive studies of CO2 in the pristine poly(1,4-phenylene ether−ether−sulfone) membrane and composite membranes were performed at 6 bar and 298 K, using pulsed field gradient NMR techniques. The evolution of the heterogeneity of the diffusion environments as seen by NMR was monitored in terms of the diffusion time and a stretching parameter. The values of the self-diffusion coefficient increase with filler content, from 2.1 × 10−8 cm2 s−1 for pristine membranes to 9.3 × 10−8 cm2 s−1 for membranes with 30 wt % of filler. Sorption and permeation experiments carried out at different pressures were used to determine the dual-mode model parameters that describe the transport processes. Apparent diffusion coefficients of CO2 in the membranes were obtained from the time lag method, from parameters of the dual-mode model,...