2002 Fiscal Year Final Research Report Summary
Development of ammonia SCR system with self-assembled photocatalyst
| Project/Area Number |
13555219
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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 | 展開研究 |
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| Research Field |
触媒・化学プロセス
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TANAKA Tsunehiro Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (70201621)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAOKA Masaki Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (80252485)
HITOMI Yutaka Graduate School of Engineering, Research Associate, 工学研究科, 助手 (20335186)
FUNABIKI Takuzo Graduate School of Engineering, Professor, 工学研究科, 教授 (70026061)
NAGAI Yasutaka Toyota Central Laboratory, Catalysis, Researcher, 触媒部, 副研究員
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| Project Period (FY) |
2001 – 2002
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| Keywords | photocatalyst / deNOx / titanium dioxide / vanadim oxide / low reactor with a fixed bed / ammonia / SCR / response to visible light |
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| Research Abstract |
We have synthesized supported metal oxide catalysts by self-assembling of the active composites and evaluate the photocatalytic activity of thus prepared catalysts. To evaluate the capability of the catalysts for partial oxidations, we carried out photooxidation of light alkanes and liquid phase photooxidation of cyclohexane. We found that Rb2O-V2O5/SiO2 exhibited high activity for the former reaction and response to visible light while for the latter V2O5/Al2O3 catalyst was found to be effective. Titanium dioxide showed comparable high activity but catalyze non selective oxidation. We carried out the evaluation of these catalyst candidates for low temperature ammonia SCR reaction (NO photo-SCR with ammonia). The reaction was carried out in a continuous flow reactor with a fixed catalyst bed which models a practical condition. The practical condition means the feed, GHSV = 4000 h-1, NO and ammonia -1000 ppm, O2 2%. Opposite to the results of partial oxidation, V2O5/Al2O3 was almost inactive and Rb2O-V2O5/SiO2 exhibited 40 % conversion of NO while TiO2 exhibited the highest activity 80% conversion rate was maintained for 100 h. We speculated that ammonia SCR is fundamentally equal to the total oxidation. By varying the reaction conditions and spectral consideration with FT-IR, UV/VIS, and ESR, we proposed the reaction mechanism of a series of elemental steps (1) adsorption of ammonia onto titanium oxide, (2) photoactivation of adsorbed ammonia, (3) reduction of NO as well as the reduction of Ti cations and (4) re-oxidation of reduced Ti cations. In the absence of oxygen. NO acts as an oxidant of the reduced Ti cations. A point of the present catalytic system is that an intermediate is a adsorbed amide radical which arisen from adosorbed ammonia and the restriction of the spin state prevent O2 from reaction with amide radical, resulting in the preferential reduction of NO.
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