| Project/Area Number |
17360391
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Catalyst/Resource chemical process
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| Research Institution | Kumamoto University |
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Principal Investigator |
MACHIDA Masato Kumamoto University, Graduate School of Engineering Sciences, Professor (70211563)
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| Co-Investigator(Kenkyū-buntansha) |
IKEUE Keita Kumamoto University, Graduate School of Engineering Sciences, Assistant Professor (60372786)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,610,000 (Direct Cost: ¥15,500,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2007: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2006: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥8,300,000 (Direct Cost: ¥8,300,000)
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| Keywords | nitrate ions / electrochemical reactor / nitrogen oxide / drinking water / solid electrolyte / Nafion / 電極触媒 / 飲料水 / 硝酸イオン還元 / 高分子固体電解質 / 浄水 / 電極 / プロトン伝導体 / 硝酸性窒素 / 水素 / 電気化学 |
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| Research Abstract |
The reduction of NO_x, in the presence of excess O_2 has been successfully achieved at 70℃ using an electrochemical cell. An H+-conducting solid polymer electrolyte(SPE)yielded hydrogen on the Pt cathode to ca+C476use the catalytic NO-H_2 reaction. It was revealed that the electrochemically evolved hydrogen on the Pt cathode is more active toward NO than molecular H_2 in the gas feed. The competitive H_2-O_2 reaction is suppressed because the Pt surface is covered with stable nitrate(NO_3)species, which blocks oxygen adsorption hereon. The combination between the SPE cell and supported Pt catalysts can broadly be applied to novel low-temperature de-NO_x processes. Electrocatalytic reduction of nitrate ions(NO_3)was also carried out over Cu-Pd and Cu-Pt bimetallic cathodes, which were deposited on a Nafion-117 H^+-conducting polymer membrane. By applying DC current to the membrane-electrode assembly(MEA), H_2 evolved on the cathode caused monotonic degradation of NO_3^- in the cathode compartment. The. NO_3^- reduction proceeded in a consecutive manner and copper increased significantly the catalytic activity for the first step from NO_3^- to NO_2^-. The Cu-Pd and Cu-Pt cathodes, having 38 and 20 at% Cu, respectively, exhibited the highest reduction rate. The product selectivity was also dependant on the content of Cu. The Cu-Pd cathode showed a lower selectivity to NO_2^- and a higher selectivity to NH_4^+, because the catalytic activity for NO_2 reduction is high. The rate of nitrate reduction was increased by supplying CO_2, which plays a role of a buffer to keep pH lower than 7 and shift the equilibrium of the reaction, 2NO_3 + 5H_2 + N_2 + 2OH^- + 4H_2O.
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