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

Abstract

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 AgNO3/SiO2 sorbent. Although Ag−Y could purify 1-butene/1,3-butadiene effectively, the purification performance was degraded by H2 and/or H2S poisoning. A new sorbent for 1-butene/1,3-butadiene purification was developed in this study by ion-exchange of Cu2+ cations into Y-zeolite followed by reduction of Cu2+ 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 H2S/H2 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 Cu2+ 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.

New sorbents for desulfurization of diesel fuels via π‐complexation

“…Initially, this adsorbent matrix was expected to perform better because of the high loadings of cuprous ions. For Cu(I)-Y, Takahashi et al (2001) used electron paramagnetic resonance (EPR) studies to show that about 50% of the Cu 2ϩ cations are autoreduced to Cu ϩ , whereas for CuCl/␥-Al 2 O 3 Golden et al (1998) found 80 -85% of the Cu 2ϩ is reduced. These results were used here to obtain the ratios of sulfur molecules adsorbed per Cu ϩ on Cu(I)-Y and CuCl/␥-Al 2 O 3 (see Table 2).…”

“…Larsen et al (1994) reported that about 40% of the cupric ions in Cu-ZSM-5 were reduced under helium at 410°C. EPR studies done by Takahashi et al (2001Takahashi et al ( , 2002 showed that 50% of Cu 2ϩ in Cu(II)-Y zeolite was reduced under vacuum or helium at 450°C, which was in good agreement with the findings of Larsen et al (1994). It should be noted that after several hours of autoreduction, the color of Cu(I)-Y was pale green, compared to a bluish green typically observed in The adsorption capacity of autoreduced Cu-Y observed for simple liquid hydrocarbon mixtures (Hernández-Maldonado and Yang 2003a) has to be due not only to the reduction of the copper ions, but also because of the final, exposed position of the cations after activation and/or during adsorption.…”

“…Therefore, this provides opportunities for tailoring and developing new adsorbents for processes where selective adsorption is needed, such as in the case of sulfur removal from fuels. Our group has already developed -complexation adsorbents for desulfurization Takahashi et al, 2002; Yang, 2003a, 2003b), olefin/paraffin, diene/olefin, and aromatics/aliphatics separations (Yang and Kikkinides, 1995;Rege et al, 1998;Huang et al, 1999aHuang et al, , 1999b Yang, 1997, 2000;Padin et al, 1999;Jayaraman et al, 2001;Takahashi et al, 2000Takahashi et al, , 2001. Hernández-Maldonado and Yang (2003a) found that both copper and silver exchanged faujasite type zeolites, Ag-Y and Cu(I)-Y, are excellent adsorbents for the removal of thiophene molecules from liquid hydrocarbon mixtures.…”

Characteristics of sulfur removal by silver-titania adsorbents at ambient conditions

“…A number of transition metal oxides have been employed for this purpose Khare 2001;Morton et al 2004aMorton et al , 2004bMorton et al , 2004cPrice et al 2003;Simon et al 2004;Sughrue et al 2003). Ni in its reduced metallic form Ma et al 2005;Velu et al 2005b), supported chloride salts of Cu and Pd (Hernández-Maldonado et al 2005b;Wang et al 2006), zeolitic structures ion exchanged with Cu, Ag, Ce, Ni have also been shown to be effective (Bhandari et al 2006;Hernández-Maldonado et al 2005b;Yang 2003, 2004c;King and Li 2006;Velu et al 2003;Xue et al 2006); particularly Y type zeolites (Bhandari et al 2006;King and Li 2006;Takahashi et al 2001a;Takahashi and Yang 2001b;Yang et al 2003Yang et al , 2004. Among support structures, SiO 2 , Al 2 O 3 (Hernández-Maldonado and Yang 2004b; Jeevanandam et al 2005;Kim et al 2006) and activated carbon (Hernández-Maldonado and Yang 2004b; Kim et al 2006) are the most common.…”

Deep desulfurization of FCC gasoline by selective adsorption over nanosized zeolite-based adsorbents

“…, which is desired for p-complexation. Auto-reduction of cupric ions to cuprous ions in synthetic zeolites has been reported by several groups [9][10][11] and a more detailed discussion on the Cu-Y auto-reduction process can be found elsewhere [12][13][14].…”