Selective Separation of Co<Sub>2</Sub> Using Novel Mixed Matrix Membranes Based on Pebax and Liquid-Like Nanoparticle Organic Hybrid Materials

Abstract

Pebax1657 is known as a promising polymeric membrane material for CO2 separation. In order to further improve its gas separation performance, different polymers containing ethylene oxide (EO) groups were incorporated into the Pebax1657 matrix to form mixed matrix membranes. Liquid-like nanoparticle organic hybrid materials (NOHM-I-HPE, “I” stands for “ionic bond” and “HPE” refers to polyetheramine (“PE”) with a high (“H”) ether group content), which were made of polyetheramine chains tethered onto functionalized silica nanoparticles, have shown high solubility of CO2. In this study, the homogenous NOHM-I-HPE/Pebax1657 mixed matrix membranes with different NOHM-IHPE loadings were prepared and investigated. The results of differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) indicated that the addition of NOHM-I-HPE resulted in a decrease in glass transition temperature of Pebax1657 and an increase in EO content of the mixed matrix membrane. Single gas permeabilities of CO2, N2 and CH4 at 23 °C and 1 bar were measured using the time-lag method. For the NOHM-I-HPE loading ranging from 0 to 60 wt.%, solubility coefficients of the mixed matrix membranes for CO2 greatly increased from 1.16 to 3.84 cm3 (STP)/(cm3·bar), while those for CH4 and N2 only slightly increased from 0.078 to 0.094 cm3 (STP)/(cm3·bar) and from 0.013 to 0.026 cm3 (STP)/(cm3·bar), respectively. CO2 permeability increased four times compared to the pure Pebax1657 membrane after the incorporation of 60 wt.% NOHM-I-HPE in Pebax1657. Although the CO2/N2 selectivity slightly decreased with an increase in the NOHM-I-HPE loading, the CO2/CH4 selectivity was improved in the newly developed NOHM-IHPE/Pebax1657 mixed matrix membranes. These results indicate that the NOHM-I-HPE/Pebax1657 mixed matrix membranes are very promising candidates for selective CO2 separation for various energy related applications.