Scalable Polymeric Few-Nanometer Organosilica Membranes for Pre-Combustion CO ₂ Capture

Abstract

Nanoporous silica membranes exhibit excellent H₂/CO₂ separation properties for sustainable H₂ production and CO₂ capture but are prepared via complicated thermal processes above 400 ^oC, which prevent their scalable production at low cost. Here, we demonstrate the rapid fabrication (within 6 minutes) of ultrathin silica membranes (≈6 nm) via oxygen plasma treatment of polydimethylsiloxane based thin-film composite membranes at 20 ^oC. The resulting organosilica membranes exhibit H₂ permeance of 280 - 930 GPU (1 GPU = 3.347×10^-10 mol m^-2 s^-1 Pa^-1) and H₂/CO₂ selectivity of 93 - 32 at 200 °C, far surpassing state-of-the-art membranes and Robeson’s upper bound for H₂/CO₂ separation. When challenged with a 3-day simulated syngas test containing water vapor and a 340-day stability test at 200 °C, the membrane shows stable separation performance. The robust H₂/CO₂ separation properties coupled with excellent scalability demonstrate the great potential of these organosilica membranes for economic H₂ production with minimal carbon emissions.

Keywords: CO2 capture, hydrogen purification, membrane separation, silica membranes