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403 results on '"Wakabayashi, Takashi"'

4. Pt Oxide Nanoclusters Supported on ZrP2O7 for Selective NOx Reduction by H2 in the Presence of O2 with Negligible NH3, N2O, and NO2 Byproducts.

Author

Machida, Masato, Nishiyama, Koshi, Furukubo, Mana, Yoshida, Hiroshi, Awaya, Keisuke, Ohyama, Junya, Tsushida, Masayuki, Suwa, Mayuko, Nagao, Yuki, Endo, Yoshinori, and Wakabayashi, Takashi

Abstract

Pt/ZrP2O7 catalysts exhibiting high activity for catalytic NOx reduction by H2 in the presence of excess O2 were developed in this study. At a low temperature of 125 °C and a high space velocity of approximately 5 × 104 h–1, 0.4 wt % Pt/ZrP2O7 facilitated a higher NO conversion to N2 (51%) than 0.4 wt % Pt/ZrO2 (<5%) for a reaction mixture of 200 ppm NO, 5000 ppm H2, 10% O2, and He balance. However, N2O and NO2 production increased at temperatures lower than 100 °C and higher than 200 °C, thereby decreasing the N2 yield. High-resolution electron microscopy and X-ray photoelectron spectroscopy analyses of 0.4 wt % Pt/ZrP2O7 revealed the coexistence of large metallic Pt crystallites with sizes of ∼20 nm and highly dispersed Pt oxide nanoclusters. When Pt loading was decreased to 0.05 wt %, the large metallic Pt crystallites disappeared, and only the Pt oxide nanoclusters remained on ZrP2O7. Owing to this structural change, N2O/NO2 formation was significantly suppressed, enabling highly selective NO reduction to N2. Moreover, catalyst preparation by equilibrium adsorption instead of wet impregnation further improved the reaction, achieving >90% selective NO conversion to N2, which was nearly free of undesired byproducts (NH3, N2O, and NO2) at 175 °C. The Pt oxide nanocluster supported on ZrP2O7 was more tolerant to the presence of 10% water vapor in the exhaust gas than the metallic Pt particles. Therefore, the developed catalyst is suitable for applications in practical exhaust gas purification for H2-fueled internal combustion engines. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Synthesis of Hexagonal YbMnO3 and Its Three-Way Catalytic Performance.

Author

Inoue, Michiyo, Iwase, Kengo, Watanabe, Satoshi, Yamaguchi, Michitaka, Nagao, Yuki, Endo, Yoshinori, Wakabayashi, Takashi, Endo, Takahiro, Hosokawa, Saburo, and Tanaka, Tsunehiro

Subjects
RARE earth metals, SPARK ignition engines, WASTE gases, PALLADIUM catalysts, AROMATIC compounds
Abstract

For stringent regulations of exhaust gases from gasoline-powered vehicles, small amount of platinum-group metals (PGMs) in automotive catalysts is highly required. To satisfy this requirement, applications of base-metal catalysts such as Fe and Mn have been vigorously discussed and investigated. Previously, we reported that rare earth metals containing hexagonal Fe and Mn oxides work as effective support materials and active species in CO oxidation, C3H6 oxidation, and NO reduction. However, most of the base-metal oxides could be readily decomposed by gasoline engine aging at approximately 1000 °C. In this study, we show that hexagonal YbMnO3 (h-YbMnO3) can be obtained as single-phase using the simple coprecipitation method with H2O2. Moreover, h-YbMnO3 can function as a oxygen storage material, which maintains its hexagonal structure after hydrothermal aging at 1000 °C for 25 h owing to the small ionic radius of Yb. On the other hand, isostructural YMnO3 (h-YMnO3) can be easily decomposed under the same aging condition. The catalytic performances of Pd loaded materials (Pd/h-YbMnO3, Pd/Al2O3, and Pd/CeO2-ZrO2 (CZ)) on cordierite honeycomb substrates were evaluated. Among them, Pd/h-YbMnO3 exhibited the highest oxidation activities even though it had significantly lower specific surface area (SSA). In particular, Pd/h-YbMnO3 exhibits a strong effect on paraffin oxidation such as C3H8, which is less reactive than other olefinic and aromatic hydrocarbons for automotive catalysts. [ABSTRACT FROM AUTHOR]

Published
2023
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35. The Rural Household's Intention to Hen House Farming ‒Survey Results from Southern Cambodia and Future Research Issues‒

Author

WAKABAYASHI, Takashi

Abstract

本稿は，養鶏の発展段階初期にあるカンボジアにおいて，鶏舎を建てての養鶏（以下，舎飼養鶏とする）に対する農村住民の意向を調査により把握し，その特徴を明らかにするとともに今後の研究課題について論じたものである。調査は，同国カンダール州，コンポンスプー州，プレイヴェン州およびタケオ州の南部４州で実施され，８か村での標本調査と１つの特定村での全数調査が行われた。論じる対象は，舎飼養鶏の経験のない世帯とした。 調査結果は，舎飼養鶏に取り組みたいと回答した世帯が約13％，取り組む気はないが考えたことがある世帯が約25％，取り組みたくない世帯が約62％であった。 取り組みたい等と回答した要因について聞き取り，その回答割合が高かった項目から明らかとなったことは，舎飼養鶏に取り組みたいか否かには，収益が考慮されること，舎飼養鶏に投入する時間があるか否かが考慮されていることであった。 取り組みたい，または取り組む気はないが考えたことがあると回答した世帯を属性別に分け，統計的に検定してもあまり差がないことが確認された。一方で，取り組みたくないと回答した世帯では，属性別に分けた場合に有意な差が確認される項目が相対的に多く，回答割合にも分散傾向が確認された。 回答を統計的に検定し，有意な差が確認された項目から得られた今後の課題は，得られた情報が回答に及ぼす影響，採算にかかる回答と年齢との関係についての研究であった。政策的課題として，支援する対象として絞り込む年齢層と金融支援の是非について検討の余地があることが示唆された。, This paper describes the characteristics of intention to engage in hen house farming（HHF）in Cambodia, where poultry farming is in the primary stage of development, and indicates the future direction of this study by finding out issues to be solved for the development of poultry farming in the country. The samples were collected by sample survey in eight villages in Kandal, Kampong Speu, Prey Veng and Takeo provinces in southern Cambodia and by complete survey in one village out of those provinces. To ascertain what prevents rural households from starting HHF, this paper concerns the answers of households not engaging in HHF out of all the rural households surveyed. Key findings are as follows. The survey results showed that 13% of rural households are ready to start HHF, 25% of households have once considered but gave up starting HHF, and 62% of the households have no intention to engage in HHF. Further interviews to discover the backgrounds of their answers revealed that profitability of HHF and leisure for HHF decide whether or not rural households have an intention of engagement in HHF. Statistical tests on stratified data（age, scale of farm, etc.）showed that there is no significant difference between households that are ready to start HHF and households that have once considered but gave up starting HHF. On the contrary, the statistical tests to households that have no intention to engage in HHF displayed significant differences in many points and variances on response rate. The analysis raised two issues to be discussed in a further study. Those are to demonstrate how obtained information about HHF affects rural household’s answers and how their responses to the question of HHF profitability are related to their ages. The analysis also indicated from a view of political measures that there is room for us to discuss age groups to be supported and the necessity of financial support.

Published
2014

42. Particle dispersibility and giant reduction in dynamic modulus of magnetic gels containing barium ferrite and iron oxide particles

Author

Mitsumata, Tetsu, Wakabayashi, Takashi, and Okazaki, Takahiko

Subjects
Barium compounds -- Chemical properties, Barium compounds -- Structure, Barium compounds -- Magnetic properties, Ferrites (Magnetic materials) -- Chemical properties, Ferrites (Magnetic materials) -- Magnetic properties, Oxidation-reduction reaction -- Analysis, Viscoelasticity -- Evaluation, Chemicals, plastics and rubber industries
Published
2008

43. Verification of the silica deficiency hypothesis based on biogeochemical trends in the aquatic continuum of Lake Biwa-Yodo River-Seto Inland Sea, Japan

Author

Harashima, Akira, Kimoto, Takashi, Wakabayashi, Takashi, and Toshiyasu, Tadao

Subjects
Biogeochemistry -- Environmental aspects, Estuaries -- Environmental aspects, Estuaries -- Composition, Silica -- Environmental aspects, Environmental issues
Abstract

The aquatic continuum composed of Lake Biwa, the Yodo River and the Seto Inland Sea, Japan, where the natural conditions make the silica deficiency less likely to emerge due to the inherently rich supply of dissolved silicate was investigated. The results showed that the silica was retained both in the lake and nearby the estuary.

Published
2006

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