551527 Advanced Nanocomposite Membranes for Natural Gas Purification

Monday, June 3, 2019: 5:18 PM
Republic ABC (Grand Hyatt San Antonio)
Jaesung Park, McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, Hee Wook Yoon, McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX and Benny D. Freeman, Mcketta Department of Chemical Engineering, Center for Energy and Environmental Resources, and Texas Materials Institute, The University of Texas at Austin, Austin, TX

Using membrane technology for removal of CO2 from natural gas is a proven technology with a track record spanning several decades. Compared with amine absorption, membrane units often operate with lower energy input, and they have a smaller footprint than conventional amine absorption units. However, conventional commercial membrane materials do not offer high-enough CO2 flux and selectivity to compete effectively with amine absorption.

In the present work, we report highly permeable polymer nanocomposites applied to natural gas purification. Using a polymer of intrinsic microporosity (PIM), which contains ethanoanthracene (EA) and Tröger base (TB) units as control material (PIM-EA(Me2)-TB), we design and synthesize a version of this PIM without methyl side chains, PIM-EA(H2)-TB. Nanocomposites are made by combining PIM-EA(H2)-TB with 10 wt. % of porous aromatic framework-1 (PAF-1) nanoparticles (which is a self-assembled microporous polymer with repeating units comprising aromatic carbon rings arranged in a tetrahedron). 13C solid state nuclear magnetic resonance (NMR) spectra and the cross-sectional scanning electron microscope (SEM) demonstrated that incorporation of PAF-1 into PIM-EA(H2)-TB yields a phase separated system. Small angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) were used to characterize the presence of PAF-1 impact on the spacing between PIM-EA(H2)-TB chains, suggesting that PAF-1 drastically enhances d-spacing in PIM-EA(H2)-TB. Pure gas permeability for CO2 and CH4 was measured as a function of upstream pressure at 35 . Incorporation of PAF-1 substantially increases pure CO2 permeability of PIM-EA(H2)-TB, but decreases pure CO2/CH4 selectivity, presumably attributed to free volume increase imparted by PAF-1 in PIM-EA(H2)-TB matrix. Permeation of mixtures of CO2 and CH4 (50:50 mol. %) are presented alongside the measurements of pure components to characterize the performance of these materials under simulated natural gas conditions.

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