High-silica (gel Si/Al = 100) SSZ-13 membranes were prepared by hydrothermal secondary growth on the surface of α-alumina hollow fiber supports. The membranes were evaluated for their performance in the separation of CO2 from equimolar mixtures with CH4 or N2. The maximum CO2-CH4 and CO2-N2 separation selectivities were found to be 42 and 12 respectively, with a high CO2 permeance of 3.0 × 10-7 mol m2 s -1 Pa-1 at 293 K and total feed pressure of 0.6 MPa. At the low aluminum content, the prepared membranes contain a very low number of defects, as follows from their H2/SF6 ideal selectivity of over 500 in the 293-473 K temperature range. Due to their hydrophobicity, water in the feed mixture has only a small influence on the permeance at temperatures above 353 K. Water improves the CO2-N2 and CO 2-CH4 selectivity, which is attributed to preferential blocking of the hydrophilic, non-zeolitic defect pores. The hydrothermal stability of the high-silica SSZ-13 membrane was evaluated by a long (220 h) CO2-N2 separation test with a humidified (9.5 kPa H 2O) feed mixture at 393 K and 0.6 MPa feed pressure. The permeance and selectivity were stable during this endurance test, underpinning the promise of high-silica SSZ-13 membranes for application in the separation of hot and humid gas mixtures.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)