| 초록 |
p-Xylene (ca. 0.58 nm) can be separated from its bulkier isomers using MFI type zeolites with 10-membered-ring pores (ca. 0.55 nm). We synthesized an unprecedented hierarchical membrane structure by introducing non-zeolitic micropores (ca. 0.6-1.5 nm) and mesopores (ca. 2-7 nm) to a typical microporous MFI type zeolite membrane. The non-zeolitic pores were uniformly embedded, which reduced defect formation and promoted molecular transport, resulting in high p-xylene perm-selectivity and molar flux. The mesoporous MFI membranes had almost double p-xylene permeance and a high p-/o-xylene separation factor when compared to a conventional, crack network-containing MFI membrane of similar thickness (ca. 1 μm). The non-zeolitic pores embedded in the non-zeolitic pores allowed for a reduction in separation performance deterioration, which was linked to the generation of coke. |
