Faculty Profiles - NAGAOKA Katsutoshi

Discovery of Face-Centered-Cubic Ruthenium Nanoparticles: Facile Size-Controlled Synthesis Using the Chemical Reduction Method Reviewed

Kohei Kusada, Hirokazu Kobayashi, Tomokazu Yamamoto, Syo Matsumura, Sumi Naoya, Katsutoshi Sato, Katsutoshi Nagaoka, Yoshiki Kubota, Hiroshi Kitagawa

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 135 ( 15 ) page： 5493 - 5496 2013.4

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

We report the first discovery of pure face-centered-cubic (fcc) Ru nanoparticles. Although the fcc structure does not exist in the bulk Ru phase diagram, fcc Ru was obtained at room temperature because of the nanosize effect. We succeeded in separately synthesizing uniformly sized nanoparticles of both fcc and hcp Ru having diameters of 2-5.5 nm by simple chemical reduction methods with different metal precursors. The prepared fcc and hcp nanoparticles were both supported on gamma-Al2O3, and their catalytic activities in CO oxidation were investigated and found to depend on their structure and size.

DOI： 10.1021/ja311261s

Monoatomically dispersed Pd/TiO2 catalyst effective for epoxidation of propylene at ambient temperature in the presence of H-2 and O-2 Reviewed

Susumu Hikazudani, Tatsuya Mochida, Naofumi Matsuo, Katsutoshi Nagaoka, Tatsumi Ishihara, Hisayoshi Kobayashi, Yusaku Takita

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL Vol. 358 page： 89 - 98 2012.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

The catalytic activity of monoatomically dispersed Pd supported on TiO2 toward propylene epoxidation in the presence of H-2 and O-2 was studied at ambient temperature, and both propylene oxide (PO) and propane were obtained. Short-chain alkanes also reacted but epoxide formation was not observed in those reactions except in the case of isobutane, which formed isobutylene oxide at a low rate. The optimum surface concentration of Pd on TiO2 was 0.005-0.01 atom/nm(2); because the supported amount of Pd is extremely small relative to the surface area of the support, the supported Pd is thought to be monoatomically dispersed. Pd/TiO2 catalysts prepared from a tetraphenylporphyrin-Pd chloride complex showed almost the same product distribution for propylene epoxidation as did catalysts prepared from Pd(NO3)(2). Isotope exchange between H-2 and D-2 proceeded over Pd/TiO2 with a low surface concentration (0.0001 atom-Pd/nm(2)), and chemical potential calculations suggested that H-2 molecules could dissociatively adsorb onto the monoatomically dispersed Pd/TiO2. A PO formation mechanism over the catalyst is proposed on the basis of these results. The results presented here may provide the first clear evidence of catalysis by monoatomically dispersed noble metals. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2012.03.001

Effect of the nature of rhodium catalyst supports on initiation of H-2 production during n-butane oxidative reforming at room temperature Reviewed

Katsutoshi Nagaoka, Katsutoshi Sato, Yusaku Takita

JOURNAL OF CATALYSIS Vol. 287 page： 86 - 92 2012.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Three rhodium catalysts supported on rare earth oxides with redox properties, Rh/CeO2, Rh/Pr6O11, and Rh/Tb4O7, were tested for their ability to trigger oxidative reforming of n-butane at room temperature. Only Rh/CeO2 triggered the oxidative reforming, owing to the heat generated by the spontaneous oxidation of the CeO2-x species produced by prior reduction of the supported catalyst with H-2. Although the three rare earth oxides were reduced to CeO1.91. Pr2O3, and Tb2O3, respectively, by H-2 at >= 873 K. CeO1.91 was the only reduced oxide that was oxidized upon exposure to O-2 at room temperature. These results indicate that the ability of the reduced oxide support to undergo oxidation at room temperature was crucial for triggering oxidative reforming of n-butane at room temperature. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2011.12.007

Mono-atomically dispersed Pd on TiO2 as a catalyst for epoxidation of light olefins at low temperatures in the presence of H-2 and O-2 Reviewed

Susumu Hikazudani, Tatsuya Mochida, Kenshiro Yano, Katsutoshi Nagaoka, Tatsumi Ishihara, Yusaku Takita

CATALYSIS COMMUNICATIONS Vol. 12 ( 15 ) page： 1396 - 1400 2011.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Palladium supported at extremely low loading on TiO2 catalyzed epoxidation of light olefins (except ethylene) in the presence of O-2 and H-2 at ambient temperature. Propylene oxide (PO) was obtained from propylene (1-2% yield; 30-60% selectivity) together with propane. Simple oxidation of H-2 to water was slow, and the ratio of H-2 used for PO formation in the reacted H-2 was 10-25%. A Pd concentration of 0.005-0.01 atom-Pd/nm(2)-TiO2 was optimum for epoxidation, and the major product at 0.02 atom-Pd/nm(2) was acetone. That the distributions for a Pd/TiO2 catalysts prepared from Pd nitrate and from a Pd-tetraphenylporphyrin complex at the same Pd loading were similar suggests that Pd was supported mono-atomically on TiO2. We propose that PO formed via reaction between propylene adsorbed on Pd and an active species derived from reaction of H-2 and O-2 on TiO2 (perhaps center dot OOH). (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2011.05.020

Oxidative Steam Reforming of Ethanol over Supported Ni Catalysts at Relatively Low Temperature Reviewed

Sato Katsutoshi, Ito Akiko, Kawano Kosuke, Takita Yusaku, Nagaoka Katsutohi

JOURNAL OF THE JAPAN PETROLEUM INSTITUTE Vol. 54 ( 5 ) page： 331 - 337 2011.9

Highly Active Cs2O/Ru/Pr6O11 as a Catalyst for Ammonia Decomposition Reviewed

Katsutoshi Nagaoka, Kyoko Honda, Megumi Ibuki, Katsutoshi Sato, Yusaku Takita

CHEMISTRY LETTERS Vol. 39 ( 9 ) page： 918 - 919 2010.9

Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

The use of a new catalyst, namely, Cs2O/5 wt % Ru/Pr6O11 (mole ratio of Cs to Ru: 1), in which Ru is supported on strong basic Pr6O11 and the strong basic promoter Cs2O is added, resulted in almost complete NH3 consumption at 673 K and an NH3 conversion of 14% even at temperatures as low as 523 K.

DOI： 10.1246/cl.2010.918

Preparation and characterization of active Ni/MgO in oxidative steam reforming of n-C(4)H(10) Reviewed

Katsutoshi Sato, Fumiaki Sago, Katsutoshi Nagaoka, Yusaku Takita

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Vol. 35 ( 11 ) page： 5393 - 5399 2010.6

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Oxidative steam reforming of n-C(4)H(10) over MgO-supported Ni catalysts is described. The Ni/MgO catalysts were prepared by the impregnation method from aqueous Ni(NO(3))(2) precursor solutions at two pH values. Ni/MgO prepared at pH 7 exhibited considerably higher activity than Ni/MgO prepared from a conventional acidic aqueous precursor solution (pH 3.5). The H(2) formation rate for the modified Ni/MgO was up to 2.3 times that for conventional Ni/MgO under a high space velocity of 1660 L(h g)(-1). Furthermore, after reduction at high temperature (1273 K), the modified Ni/MgO showed a higher H(2) formation rate than did Rh/MgO. The superior performance of the modified Ni/MgO was ascribed to stronger resistance to oxidation of Ni(o) due to the formation of relatively large Ni(o) particles. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2010.03.028

Hydrogen Production from Bioethanol: Oxidative Steam Reforming of Aqueous Ethanol Triggered by Oxidation of Ni/Ce0.5Zr0.5O2-x at Low Temperature Reviewed

Katsutoshi Sato, Kosuke Kawano, Akiko Ito, Yusaku Takita, Katsutoshi Nagaoka

CHEMSUSCHEM Vol. 3 ( 12 ) page： 1364 - 1366 2010

Metal phosphate and fluoride catalysts active for hydrolysis of NF3 Reviewed

Takeshi Takubo, Yutaka Hirose, Daishin Kashiwagi, Takanori Inoue, Hisatoshi Yamada, Katsutoshi Nagaoka, Yusaku Takita

CATALYSIS COMMUNICATIONS Vol. 11 ( 3 ) page： 147 - 150 2009.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

NF3 was decomposed over various ortho, pyrophosphates and some fluorides at 450-600 K. Mn2P2O7 and CePO4 were the most active. The catalytic activity of Co2P2O7, Co-3(PO4)(2), CrPO4, Cu2P2O7, and Cr-4(P2O7)(3) followed in this order. Zn-3(PO4)(2) and AlPO4 were less active. Activity of pyrophosphate was comparable to that of ortho-phosphate. Products were NO2 and a very small amount of N2O except for HE An essential reaction was 2NF(3) + 3H(2)O -> 6HF + NO + NO2. Catalytic activity of phosphates was proportional to not the amount but the concentration of surface hydroxyls, suggesting that the reaction proceeds via a bidentate surface intermediate. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2009.09.005

Catalytic behavior of Ni/ZrxTi1-xO2 and the effect of SiO2 doping in oxidative steam reforming of n-butane Reviewed

Mechanism of Promotion Effects of Ce added to AlPO4 Effective for CFC Decomposition Reviewed

Takubo Takeshi, Sato Daigo, Inao Yasutaka, Nishiguchi Hiroyasu, Nagaoka Katsutoshi, Takita Yusaku

KAGAKU KOGAKU RONBUNSHU Vol. 35 ( 6 ) page： 623 - 632 2009.11

Fumiaki Sago, Sho Fukuda, Katsutoshi Sato, Katsutoshi Nagaoka, Hiroyasu Nishiguchi, Yusaku Takita

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Vol. 34 ( 19 ) page： 8046 - 8052 2009.10

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Catalytic behaviors of TiO2-, Zr0.5Ti0.5O2-, and ZrO2-supported Ni catalysts were investigated for oxidative steam reforming of n-C4H10 at 723 K. The composite oxide support, Zr0.5Ti0.5O2, shows high specific surface area (136 m(2)/g), leading to fine Ni particles. Thus, the Ni/Zr0.5Ti0.5O2 catalyst exhibits higher and more stable activity than that exhibited by other catalysts. However, relatively large amounts of coke are deposited on the catalyst during reaction. Thus, to retard carbon deposition, the influence of SiO2 additive was studied. Large amounts of SiO2 additive (5 or 10 mol%) decrease initial activity; at 10 mol%, degradation is also induced by oxidation of Ni-o. However, small amounts of SiO2 additive (1.5 mol%) effectively retard coking without lowering initial activity. The resultant Ni/Zr0.5Ti0.5O2-SiO2 (1.5 mol%) catalyst exhibits high and stable activity without coking. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2009.08.005

Oxidative reforming of n-C4H10 triggered at ambient temperature over reduced Ni/CeO2 Reviewed

Initiation of Oxidative Reforming of Butane over Praseodymium Oxide Supported Ni Catalysts at Ambient Temperature Reviewed

Sato Katsutoshi, Nagaoka Katsutoshi, Nishiguchi Hiroyasu, Takita Yusaku

JOURNAL OF THE JAPAN PETROLEUM INSTITUTE Vol. 52 ( 5 ) page： 295 - 296 2009.9

Katsutoshi Sato, Kouhei Adachi, Katsutoshi Nagaoka, Hiroyasu Nishiguchi, Yusaku Takita

CATALYSIS COMMUNICATIONS Vol. 10 ( 11 ) page： 1478 - 1481 2009.6

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

We investigated the oxidative reforming (OR) of n-C4H10 over Ni/CeO2 catalysts with different amounts of Ni loading at ambient temperature by feeding a reaction mixture. The OR of n-C4H10 was triggered rapidly over all the Ni/CeO2 catalysts reduced at 1073 K. O-2 absorption at 323 K revealed that the support was composed of CeO1.76 regardless of Ni loading after reduction. We concluded that the heat produced by spontaneous oxidation of CeO1.76 to CeO2 heated the catalysts to catalytic autoignition temperature. Among the catalysts, 1 wt% Ni/CeO2 exhibited durability against carbon deposition as well as excellent catalytic activity for OR in a cyclic activity test. (C) 2009 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.catcom.2009.03.028

Catalytic activity of rare earth phosphates for SF6 decomposition and promotion effects of rare earths added into AlPO4 Reviewed

Daishin Kashiwagi, Asami Takai, Takeshi Takubo, Hisatoshi Yamada, Takanori Inoue, Katsutoshi Nagaoka, Yusaku Takita

JOURNAL OF COLLOID AND INTERFACE SCIENCE Vol. 332 ( 1 ) page： 136 - 144 2009.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

SF6 was selectively hydrolyzed to SO3 over rare earth (RE) phosphates above 800 K. CePO4 was the most active catalyst, followed by GdPO4, YbPO4, DyPO4, ErPO4, SmPO4, PrPO4, TbPO4, NdPO4, and LaPO4. The middle RE phosphates were found to be more active than the light RE phosphates, but the reason for the high activity of CePO4, which belongs to the light RE group, is not clear. The catalytic activity was independent of the specific surface area (SSA), acid amount, and acid concentration of the catalysts. RE phosphates were single-phase, and a broad inversely proportional relation was observed between the crystallite size and SSA, except in the case of CePO4. The combination of highly active AlPO4 and CePO4 creates synergetic effects in the catalytic activity and SO3 selectivity over all ranges of composition. Binary catalysts were a mixture of small crystalline AlPO4 and CePO4. The addition of Ce promoted the crystallization of AlPO4, which was controlled to about 10 nm at 10-50% Ce content. The turnover frequency for SF6 decomposition was proportional to the surface concentration of hydroxyls of binary catalysts. Therefore, synergy effects may come from the number of hydroxyl (OH) pair sites on which a bidentate intermediate of hydrolysis of SF6 may be formed by the moderate crystallization of AlPO4. The addition of Ce, Pr, or Y to AlPO4 brings about a small promotion effect for SF6 decomposition, but the addition of La, Nd > Gd > Yb diminishes the activity. The addition of Gd, Pr, or Nd greatly improved the SO3 selectivity. A linear relationship between catalytic activity and the concentration of surface hydroxyls of the catalysts supports a reaction mechanism in which two F atoms of an SF6 molecule interact with two surface hydroxyls to form a bidentate intermediate. (c) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2008.12.003

A novel nanotube of composite of calcium carbonate and calcium sulfate Reviewed

Hisao Sugihara, Kotaro Inoue, Maiko Nakayama, Takanori Inoue, Katsutoshi Nagaoka, Yusaku Takita

MATERIALS LETTERS Vol. 63 ( 2 ) page： 322 - 324 2009.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Nanotube-shaped precursor which is composed of layered structured sodium dodecylsulfate (SDS) calcium carbonate were obtained by titration of an aqueous solution of Na(2)CO(3) into an aqueous solution containing CaCl(2) and SDS at 333-335 K. A unit of the repetition of the precursor was about 4 nm. Nanotube-shaped composite which is composed of CaCO(3) and CaSO(4) of 100-200 nm in diameter and 0.5-2 mu m in length was obtained from nanotube-shaped precursor composed of layers of CaCO(3) and SDS by calcinations at 673 K in air. The precursor sheet composed of CaCO(3) layers on which SDS molecules attached to both side seemed to curl up and form a pipe. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2008.10.025

Metal Phosphate Catalysts Effective for Degradation of Sulfur Hexafluoride Reviewed

Daishin Kashiwagi, Asami Takai, Takeshi Takubo, Katsutoshi Nagaoka, Takanori Inoue, Yusaku Takita

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Vol. 48 ( 2 ) page： 632 - 640 2009.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

SF6 decomposed stably over AlPO4, CePO4, YPO4, and Zr-3(PO4)(4) at 800-1000 K, but Ca2P2O7, Mg2P2O7, and Sr2P2O7 were less active. Active catalysts crystallized during the reaction. SO3, SO2F2, and HF were obtained as major products. SO3 was selectively formed over YPO4 and Zr-3(PO4)(4), but SO2F2 formed over AlPO4 and CePO4 in a significant selectivity at lower temperatures. Decomposition activity was independent of the concentration of oxygen, but it was dependent on the concentration of water vapor, suggesting that hydrolysis is the essential reaction. Catalytic activity was independent of the acidity of the catalysts. Catalytic activity was independent of the amount of surface hydroxyls, but it was correlated with the concentration of surface hydroxyls. From an analogy of hydrolysis Of CCl2F2 on AlPO4, degradation may proceed via a similar bidentate surface intermediate, OsurfaceH center dot center dot center dot F(SF4)F center dot center dot center dot HOsurface, in which two fluorine atoms of SF6 interacted with two surface hydroxyls. AlPO4 showed a steady activity and high selectivity at 843 K for 25 h, suggesting a long catalyst life. AlF3 was significantly less active than metal phosphates. This suggests that development of the catalysts which are not transformed into metal fluorides is important.

DOI： 10.1021/ie8001099

n-C4H10 autothermal reforming over MgO-supported base metal catalysts Reviewed

Katsutoshi Sato, Katsutoshi Nagaoka, Hiroyasu Nishiguchi, Yusaku Takita

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Vol. 34 ( 1 ) page： 333 - 342 2009.1

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

We report n-C4H10 autothermal reforming over MgO-supported base metal catalysts at 723 K. Catalytic performance was investigated not only after H-2 treatment at 1073 K (reductive treatment) but also after subsequent O-2/Ar treatment at the reaction temperature (oxidative treatment) to mimic the shutdown and startup of a domestic fuel cell system. After reductive treatment, both Ni/MgO and Co/MgO exhibited high n-C4H10 conversion and hydrogen formation activity; the stability of Ni/MgO was better than that of Co/MgO. The reaction route was investigated by measuring activity at various contact times. The results revealed that n-C4H10 autothermal reforming over Ni/MgO is a multi-step reaction composed of combustion, steam reforming, water gas shift reaction, and methanation. In contrast, Cu/MgO and Fe/Mgo did not show reforming activity but cracking and combustion of n-C4H10. Ni/MgO and Co/MgO catalyzed H-2 formation even after the oxidative treatment. However, the initial activity of Co/MgO after the oxidative treatment was lower than that after the reductive treatment and a decrease in H-2 formation rate was again observed after 6 h in Co/MgO, similar to the measurements after the reductive treatment. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2008.10.014