title: Further evidence for the existence of a dual-Cu+ site in MFI working as the efficient site for C2H6 adsorption at room temperature.
abstract: We have recently clarified the following point: a dual-type site, which is composed of a pair of monovalent copper ions (Cu(+)) formed in a copper-ion-exchanged MFI-type zeolite (CuMFI), functions as the active center for strong ethane (C2H6) adsorption even at room temperature rather than a single-type site composed of a Cu(+) ion. However, the character of the dual-Cu(+) site in a CuMFI is not yet fully understood. In this study, we have elucidated the nature of the active sites for C2H6 based on infrared (IR) and calorimetric data. On the basis of the results obtained, we came to the conclusion that the dual-Cu(+) site composed of Cu(+) ions giving the adsorption energy of 100 kJ mol(-1) and the absorption band at 2151 cm(-1) for carbon monoxide (used as a probe molecule) at room temperature functions as an adsorption site for C2H6. We also evaluated, for the first time, the interaction between the dual-Cu(+) site and C2H6 energetically, by the direct measurement of heat of adsorption. The value of 67 kJ mol(-1) that we recorded was higher than that for the single-Cu(+) site in this sample and also for other samples, such as NaMFI and HMFI.
authors.affiliation: Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Itadani
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sogawa
authors.forename: Akira
authors.initials: A
authors.lastname: Oda
authors.forename: Hiroe
authors.initials: H
authors.lastname: Torigoe
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Yasushige
authors.initials: Y
authors.lastname: Kuroda
mesh_terms: D000327:Adsorption; D002248:Carbon Monoxide / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004980:Ethane / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D017641:Zeolites / Q000737:chemistry*
chemical_list: D017641:Zeolites; D003300:Copper; D002248:Carbon Monoxide; D004980:Ethane