Scalable Polymeric Few-Nanometer Organosilica Membranes for Pre-Combustion CO <sub>2</sub> 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.