A new class of fillers in mixed matrix membranes: Use of synthetic silico-metallic mineral particles (SSMMP) as a highly selective component for CO2/N2 separation

Abstract

Membrane-based CO2 separation technology is a promising technology with low operating and energy costs and high scalability. This work describes the influence of synthetic silico-metallic mineral particles (SSMMP) and SSMMP/ionic liquids (IL) associated with polysulfone (PSF) to produce new mixed matrix membranes (MMM) for post-combustion technology. SSMMP is the precursor of synthetic talc undergoing no hydrothermal process resulting in a low-cost, energy-demanding, and CO2-free emission material due to its synthesis process. SSMMP have many reactive OH groups free on their surface making this material ideal to be compatibilized in a polymeric matrix. IL was immobilized in SSMMP to further improve CO2 affinity. As far as we know, this is the first time this material has been used to obtain MMMs. MMMs were prepared with concentrations of 0.5, 1, 2 and 3 wt% of fillers via melting solution and solvent evaporation. The obtained MMMs were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) with elemental mapping, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Permeability analyses were carried out at 25 °C and 0.4 MPa. The addition of pristine SSMMP and SSMMP/Im(nBu)Tf2N improved membrane selectivity decreasing the permeability for the majority of tested filler content. When using SSMMP/Im(nBu)I to obtain MMMs a different behavior was observed decreasing selectivity (except for MMM with 2% (w/w) of filler) and increasing permeability in all studied concentrations. The best result was obtained for sample SSMMP/Im(nBu)Tf2N (2% w/w) achieving a selectivity of 71.9, four times higher than pristine polysulfone membrane.

Keywords

• Mixed matrix membranes
• SSMMPs
• CO2/N2 separation
• Ionic liquids