Gas adsorptive properties of manganese dioxides
| Project/Area Number |
03640662
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
鉱物学(含岩石・鉱床学)
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| Research Institution | Hokkaido University |
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Principal Investigator |
MIURA Hiroyuki Hokkaido University,Faculty of Science,Lecturer, 理学部, 講師 (70157436)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Takeshi Hokkaido University,Faculty of Science,Associate Professor, 理学部, 助教授 (60211190)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1991: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | manganese dioxide / gas adsorption / carbon dioxide / manganese dioxide mineral / ramsdellite / groutite / 炭酸マンガン / 二酸化マンガン国際標準サンプル |
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| Research Abstract |
Manganese oxide minerals adsorb some kinds of gas molecules on their surface and released them on heating. The released gas from natural and synthetic manganese oxide minerals was studied by Q-pole mass spectrometer. CO_2 was observed in the temperature range 100-350 ﾟC, 400-450ﾟC and 600-700ﾟC. The released CO_2 gas between 100 and 350 ﾟC derived from the surface adsorption. Natural and synthetic manganese dioxide minerals adsorb CO_2 gas in the air readily.
Manganese hydroxide mineral was synthesized by the reduction of ramsdellite (gamma-MnO_2) using hydrothermal techniques in order to find the new manganese oxide which adsorb CO_2 gas. Powdered ramsdellite and manganese metal was sealed in a Pt tube with water and keep it at 150 ﾟC, 1000 kb for 10 days. The reaction is written as follows. 8MnO_2 + 2H_2O + Mn -> 4Mn_2O_3(OH) + MnO_2. Manganese metal is added to reduce the oxygen pressure in the tube and stabilize manganese ion as Mn^<3+> and Mn^<4+>. The X-ray powder diffraction profile of the product is quite similar to that of ramsdellite and groutite( gamma-MnOOH). The crystal structure, refined by the Retveldt method, is isostructure to ramsdellite and groutite. The ideal formula for the product is Mn^<3+>_2Mn^<4+>_2O_6(OH)_2. In the process of reduction, ramsdellite + new phase or new phase + groutite is observed. Therefore it is obvious that the solid solution between ramsdellite and groutite is absent.
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Report
(3 results)
Research Products
(1 results)
