Enhanced CO 2 separation performance for tertiary amine‐silica membranes via thermally induced local liberation of CH 3 Cl

A facile method for the fabrication of amine‐silica membranes with enhanced CO 2 separation performance was proposed via the thermally induced liberation of small molecules from quaternary ammonium salt. Quaternary ammonium‐silica (QA‐SiO 1.5 ) xerogel powders/films were fabricated via sol‐gel processing and their thermal stability was systematically studied using thermogravimetric mass spectrometer, Fourier transform infrared, energy dispersive spectroscopy, and positron annihilation lifetime spectroscopy analysis. CO 2 sorption performances of QA‐SiO 1.5 derived xerogel powders were quantitatively compared after assigning their relevant parameters to a dual‐mode sorption model. The gas permeation performances of membranes derived from QA‐SiO 1.5 were evaluated in terms of kinetic diameter and temperature dependence of gas permeance, and activation energy (E p ) required for gas permeation. The results indicate that liberation of the CH 3 Cl molecules from these membranes significantly improved both CO 2 permeation and CO 2 /N 2 separation capabilities. Therefore, the present study provides insight that should be useful in the development of high‐performance CO 2 separation membranes via the effect of the thermally induced liberation of small molecules. © 2017 American Institute of Chemical Engineers AIChE J , 64: 1528–1539, 2018