High performance fluoride MFI membranes for efficient CO2/H2 separation
Liang Yu, Mojtaba Sinaei Nobandegani, Jonas Hedlund
Abstract
In the present work, ultra-thin MFI zeolite membranes prepared in fluoride media were evaluated for separation of equimolar CO2/H2 gas mixtures. Both dry and humid mixtures were evaluated. For dry gas mixtures, the membrane selectivity increased from 13 to 45 when the temperature decreased from 318 to 285 K, and CO2 flux was very high and almost constant at 4 mol m−2 s−1, corresponding to CO2 permeance of 100 × 10−7 mol m−2 s−1 Pa−1 (29851 GPU). For humid gas mixtures with a partial pressure of water of 3.5 kPa, the CO2 flux decreased from 3.27 to 0.10 mol m−2 s−1 when the temperature decreased from 316 to 288 K. The corresponding CO2 permeance decreased from 79 to 2.5 × 10−7 mol m−2 s−1 Pa−1 (from 23582 to 746 GPU). At the highest temperature 318 K, the CO2/H2 separation selectivity was slightly higher for the humid gas mixture. For the humid gas mixture, the CO2 flux increased from 3.27 to 3.76 mol m−2 s−1 at 318 K and from 0.52 to 0.90 mol m−2 s−1 at 296 K when the permeate pressure was reduced from atmospheric to vacuum, respectively. The separation selectivity of CO2/H2 was almost not affected by the permeate pressure. The results show that ultra-thin fluoride MFI zeolite membranes are promising candidates for separation of CO2 from dry or humid synthesis gas.