Fabrication and characterization of Pebax-1657 mixed matrix membrane loaded with Si-CHA zeolite for CO2 separation from CH4

Polymeric membranes performance in gas separation can be improved by using zeolites as the filler in the polymer matrix to form mixed matrix membranes (MMMs). Pure-silica Si-CHA zeolite and Pebax-1657 copolymer are individually capable of separating acid gases from natural gas. However, the corresponding MMM has not been investigated in the literature. Therefore, in this work, Si-CHA zeolite was incorporated in the Pebax1657 copolymer by solvent evaporation method to evaluate its performance in CO2 separation from CH4. The fillers distribution in the polymeric matrix, structural characteristics, and interaction of fillers with the polymer in MMMs were characterized via SEM, FTIR, DSC, XRD, and stress-strain analyses. Moreover, the CO2/CH4 separation tests of the membrane as a function of zeolite content and applied feed pressure was explored. The structural analyses of the membranes showed the best filler distribution and the filler-polymer interaction in the membrane for the sample containing 10 wt% of the filler. Furthermore, pure gas permeation tests revealed that the best separation performance was obtained for the same membrane at an applied gauge pressure of 4 bar. In this membrane, 103% improvement in CO2 permeability, and 71% increase in CO2/CH4 ideal selectivity was achieved compared to the neat polymeric membrane. The separation performance of the MMM 10% was evaluated using CO2?CH4 mixed gas. In this situation, decreased CO2/CH4 separation factor was observed due to the plasticization of PEO chains with polar CO2 gas.

Automated summary

This study investigates the performance of polymeric membranes in CO2 separation from CH4 by using mixed matrix membrane (MMMs) technology, analyzing the distribution of fillers, structural characteristics, and interaction between fillers and polymers. Compared to neat polymeric membranes, MMMs show significant improvements in CO2 permeability and CO2/CH4 ideal selectivity.