Mixed matrix membranes comprising polymers of intrinsic microporosity and covalent organic framework for gas separation

Abstract

Polymers of intrinsic microporosity (PIMs) exhibit the inherent superior permeability over traditional commercial polymers, however, the relatively low selectivity restrict their broad application in gas separation. In this study, novel kinds of mixed matrix membranes (MMMs) combined covalent organic frameworks (COFs) and PIMs were prepared and utilized for improving the selectivity of carbon capture process. Covalent organic framework (SNW-1) was synthesized via Schiff base chemistry and incorporated into polymer of intrinsic microporosity (PIM-1) to prepare MMMs. Pure gas permeation tests and mixed gases separation performances of the MMMs were conducted. Owing to its proper porosity characteristics and good compatibility with PIM-1 matrix, the incorporation of SNW-1 significantly intensified the diffusion process of CO2 within the membrane. Compared with pure PIM-1 membrane, the prepared MMMs showed an increment of 27.4% and 37.6% in selectivity of CO2/CH4 and CO2/N2 along with an enhancement of 116% in CO2 permeability. The strategy of incorporating COFs into polymers of intrinsic microporosity may hold promising potential in preparing high performance MMMs for gas separation.