Abstract
CO 2-selective membranes containing both amine carriers and fumed silica (FS) in crosslinked poly(vinyl alcohol)–poly(siloxane) (PVA–POS) (FS loading < 22 wt%) and crosslinked PVA (FS loading > 22 wt%) were synthesized for CO 2/H 2 separation. The effects of temperature, feed pressure, gas relative humidities (or water contents) on the feed and sweep sides, crosslinking degree of PVA, and FS loading on transport properties including CO 2 permeability, CO 2/H 2 selectivity, and H 2 permeability, were investigated using a mixed gas containing 20% CO 2 and 80% H 2. The optimal temperature identified was 107 °C. The CO 2 permeability and CO 2/H 2 selectivity typically increased with the relative humidities on the feed and sweep sides. Increasing the crosslinking degree of PVA slightly decreased the CO 2 permeability. The CO 2 permeability and CO 2/H 2 selectivity decreased with increasing feed pressure due to the carrier saturation phenomenon. The CO 2/H 2 selectivity increased by 33.8% from 65 to 87 as FS loading increased from 12 wt% to 22.3 wt% while CO 2 permeability remained nearly constant at about 1130 Barrers. Further increase of FS loading decreased both CO 2/H 2 selectivity and CO 2 permeability. At 107 °C and 220 psia, the membrane with 22.3 wt% FS loading showed the best performance with a CO 2 permeability of 1296 Barrers (1 Barrer = 3.35 × 10 −16 mol m/(m 2 s Pa)) and a CO 2/H 2 selectivity of 87.
Published Version
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