High performance composite membranes comprising Zn(pyrz)(2)(SiF6) nanocrystals for CO2/CH4 separation

Abstract

Nanocsrystals of Zn(pyrz)(2)(SiF6) (or SIFSIX-3-Zn) metal-organic framework were synthesized by a facile sonochemical means and incorporated into a polyimide membrane to realize an excellent CO2/CH4 separation performance. Zn(pyrz)(2)(SiF6) nanocrystals selectively took up a large amount of CO2 even at low pressure while negligible uptake was observed for CH4. This implies that Zn(pyrz)(2)(SiF6) is an ideal filler to improve CO2/CH4 separation performance of polymer membrane via selective transport of CO2 over CH4. Subsequently, high-quality mixed-matrix membranes that are free of filler/polymer interfacial voids were successfully fabricated by employing house-made polyimide as a polymer matrix. Binary CO2/CH4 mixture gas permeation tests revealed that both CO2 permeability and CO2/CH4 selectivity of mixed-matrix membranes, especially for the membrane with 20 wt% filler loading, were significantly improved compared to those of pure polymeric membrane owing to the selective CO2 uptake and transport by Zn(pyrz)(2)(SiF6) crystals. As a result, a high performance surpassing the upper bound limit for polymeric membranes was achieved. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.