Cu(I)−Y-Zeolite as a Superior Adsorbent for Diene/Olefin Separation

Purification of normal α-olefins by removal of dienes has been demonstrated previously in our laboratories by π-complexation using Ag + ion-exchanged zeolite (Ag−Y) or AgNO 3 /SiO 2 sorbent. Although Ag−Y could purify 1-butene/1,3-butadiene effectively, the purification performance was degraded by H 2 and/or H 2 S poisoning. A new sorbent for 1-butene/1,3-butadiene purification was developed in this study by ion-exchange of Cu 2+ cations into Y-zeolite followed by reduction of Cu 2+ to Cu + . The performance of the Cu + -zeolite, Cu(I)−Y or Cu−Y, was found to be superior to that of Ag−Y. Cu−Y exhibited higher diene/olefin separation factors than Ag−Y by approximately an order of magnitude. Furthermore, unlike Ag−Y, exposure to H 2 S/H 2 at 120 °C had virtually no effect on 1,3-butadiene/1-butene adsorption, indicating the excellent poisoning resistance of Cu−Y. XPS and EPR analyses showed that half of the Cu 2+ cations in Cu−Y underwent autoreduction to Cu + either in vacuo or in He, resulting in the same purification capability with Cu−Y obtained by reduction with CO.