Nobuki Oka
Mitsubishi Heavy Industries
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Studies in Surface Science and Catalysis | 1997
Jun Izumi; Akinori Yasutake; Nariyuki Tomonaga; Nobuki Oka; Hiromitsu Ota; Nobuo Akutsu; Satoshi Umeda; Motoaki Tajima
Summary In this study, the precise window shrinkage of Na-A type zeolite (Na-A) in the order of 0.1by calcination after rehydration, a partial K exchange and low temperature adsorption was evaluated[1],[2],[3]. It was understood that the precise window shrinkage of thermally and chemically modified Na-A was related to the behavior of Na located in the center of 8 oxygen members ring. Following the adsorption evaluation of oxygen selectivity based on an oxygen/nitrogen binary system and CO2 selectivity based on CO2/nitrogen binary system, a more precise relationship between the window shrinkage and the behavior of Na located at the center of 8 oxygen members ring was studied with an MAS-NMR, a single crystal X-ray diffraction (SCXD) and a molecular dynamic simulation (MD).
Adsorption-journal of The International Adsorption Society | 2000
Nobuki Oka; Jun Izumi; Motoyuki Suzuki
Accordingly, the observation of oxygen selectivity on Na-K-A would indicate that nitrogen has a greater steric hindrance at the window than does oxygen. Using single crystal X-ray diffraction (SCXD), it was confirmed that K at 8-member rings was relocated to 6-member rings and that the location of Na at 8-member rings became uncertain with calcination. It was also observed that Na-K-A was thermally more stable than Na-A. Using magic angle spin nuclear magnetic resonance (MAS-NMR), it was confirmed that Na at 8-member rings irreversibly changed location from a symmetric position to an asymmetric position with calcination.Using the atomic positions determined by SCXD, the mean square displacements (MSD) of oxygen and nitrogen inside the crystal of Na-A and Na-K-A were estimated by means of molecular dynamic simulation (MD). When temperature was decreased, the MSD of nitrogen was reduced to a greater extent than that of oxygen and the MSD of nitrogen inside Na-K-A was reduced by a greater margin than that inside Na-A.
Kagaku Kogaku Ronbunshu | 2006
Yosuke Matsukuma; Kaoru Sadagata; Hidemasa Kakigami; Gen Inoue; Masaki Minemoto; Akinori Yasutake; Nobuki Oka
Kagaku Kogaku Ronbunshu | 2006
Yosuke Matsukuma; Yuichi Matsushita; Hidemasa Kakigami; Gen Inoue; Masaki Minemoto; Akinori Yasutake; Nobuki Oka
Journal of Physics and Chemistry of Solids | 2009
Yasunori Iwai; Nobuki Oka; Toshihiko Yamanishi
Archive | 2010
Naotaka Komatsu; Toshiro Nishi; Nobuki Oka; 直隆 小松; 伸樹 岡; 敏郎 西
Kagaku Kogaku Ronbunshu | 2008
Hidemasa Kakigami; Gen Inoue; Yousuke Matsukuma; Masaki Minemoto; Akinori Yasutake; Nobuki Oka
Archive | 2004
Kuniaki Ara; Kazuya Kurome; Toshiro Nishi; Hiroaki Ohira; Nobuki Oka; Mikio Toda; Hiroyuki Tsutaya; Naoki Yoshioka; 直樹 吉岡; 博昭 大平; 伸樹 岡; 幹雄 戸田; 邦章 荒; 博之 蔦谷; 敏郎 西; 和也 黒目
Archive | 2011
Kuniaki Ara; Junichi Saito; Hiroyuki Sato; Nobuki Oka; Masahiko Nagai; Koichi Fukunaga
Archive | 2011
Kuniaki Ara; Junichi Saito; Hiroyuki Sato; Nobuki Oka; Masahiko Nagai; Koichi Fukunaga