Propylene/propane and ethylene/ethane separation was examined with Ag-exchanged X-type zeolite membrane (Ag-X membrane). The Na-X membrane was prepared on a porous tubular α-alumina support by a secondary growth method. The resulting Na-X membrane was ion-exchanged by using AgNO 3 aq. Olefin selectivities in both mixtures were markedly improved after the ion exchange from Na to Ag cation. The Ag-X membrane exhibited a maximum propylene selectivity of 55.4 with a permeance of 4.13 × 10 -8 mol m -2 s -1 Pa -1 at 353 K for a propylene/propane (50:50) mixture. This membrane also exhibited a maximum ethylene selectivity of 15.9 with a permeance of 9.04 × 10 -8 mol m -2 s -1 Pa -1 at 303 K for an ethylene/ethane (50:50) mixture. We consider that the strong interaction between olefin and Ag cation plays an important role for the appearance of such high selectivity of olefin.
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