title: Material Exhibiting Efficient CO2 Adsorption at Room Temperature for Concentrations Lower Than 1000 ppm: Elucidation of the State of Barium Ion Exchanged in an MFI-Type Zeolite.
abstract: Carbon dioxide (CO2) gas is well-known as a greenhouse gas that leads to global warming. Many efforts have been made to capture CO2 from coal-fired power plants, as well as to reduce the amounts of excess CO2 in the atmosphere to around 400 ppm. However, this is not a simple task, particularly in the lower pressure region than 1000 ppm. This is because the CO2 molecule is chemically stable and has a relatively low reactivity. In the present study, the CO2 adsorption at room temperature on MFI-type zeolites exchanged with alkaline-earth-metal ions, with focus on CO2 concentrations <1000 ppm, was investigated both experimentally and by calculation. These materials exhibited a particularly efficient adsorption capability for CO2, compared with other presented samples, such as the sodium-form and transition-metal ion-exchanged MFI-type zeolites. Ethyne (C2H2) was used as a probe molecule. Analyses were carried out with IR spectroscopy and X-ray absorption, and provided significant information regarding the presence of the M(2+)-O(2-)-M(2+) (M(2+): alkaline-earth-metal ion) species formed in the samples. It was subsequently determined that this species acts as a highly efficient site for CO2 adsorption at room temperature under very low pressure, compared to a single M(2+) species. A further advantage is that this material can be easily regenerated by a treatment, e.g., through the application of the temperature swing adsorption process, at relatively low temperatures (300-473 K).
authors.affiliation: Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University , 3-1-1 Tsushima, Kita-ku, Okayama 700-8530, Japan.|Graduate School of Science and Technology, Niigata University , 8050 Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Itadani
authors.affiliation: Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University , 3-1-1 Tsushima, Kita-ku, Okayama 700-8530, Japan.|Precursory Research for Embryonic Science and Technology (PREST), Japan Science and Technology Agency (JST) , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Oda
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: Hiroe
authors.initials: H
authors.lastname: Torigoe
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: Takahiro
authors.initials: T
authors.lastname: Ohkubo
authors.affiliation: Department of Chemistry and Chemical Engineering, Niigata University , 8050 Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181, Japan.
authors.forename: Mineo
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Chemistry and Materials Technology, Kyoto Institute of Technology , Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Kobayashi
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: Yasushige
authors.initials: Y
authors.lastname: Kuroda
keywords: BaMFI; CO2 adsorption at 300 K; M2+−O2−−M2+ (M: alkaline-earth-metal ion); acetylide species; easy regeneration of the sample; fast adsorption