Faculty Profiles - NAGAOKA Katsutoshi

Papers - NAGAOKA Katsutoshi

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Synthesis and characterization of molybdenum incorporated mesoporous aluminophosphate Reviewed

Li-Ngee Ho, Tasuku Ikegawa, Hiroyasu Nishiguchi, Katsutoshi Nagaoka, Yusaku Takita

APPLIED SURFACE SCIENCE Vol. 252 ( 18 ) page： 6260 - 6268 2006.7

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

A synthesis of molybdenum incorporated mesoporous aluminophosphate with long-chain n-alkylarnine as template material had been prepared under non-aqueous condition. These materials were extensively characterized by using X-ray diffraction (XRD), nitrogen sorption isotherms, nuclear magnetic resonance of Al-27 and P-31 (NMR), inductive coupled plasma (ICP), electron spin resonance (ESR), Fourier transform infrared (FTIR) and thermogravitnetric-differential thermal analysis (TG-DTA). Morphology of the materials had been observed by using transmission electron microscope (TEM) that revealed the mesoporous materials possessed wormhole-like structures. Alkaline solvent extraction using n-butylamine/ethanol had been efficiently removed the n-alkylamine from the mesoporous samples which yielded BET surface areas around 550-730 m(2)/g. BJH analysis showed a narrow pore size distribution which increased with increasing of the carbon chain length of alkylamine (template). Valence state and coordination of the molybdenum in the obtained samples were investigated by using ESR and FTIR where it was found that Mo4+ and Mo6+ molybdenum species existed in the molybdenum incorporated mesoporous aluminophosphate in tetrahedral coordination. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2005.08.064

Other Link： http://orcid.org/0000-0003-1774-1537

Ni/(rare earth phosphate) as a new effective catalyst for autothermal reforming of methane Reviewed

Katsutoshi Nagaoka, Toshikazu Eiraku, Hiroyasu Nishiguchi, Yusaku Takita

CHEMISTRY LETTERS Vol. 35 ( 6 ) page： 580 - 581 2006.6

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

The stability of metal phosphate during H-2 reduction is one of the critical factors that determine the catalytic behavior of Ni/(metal phosphate) in CH4 autothermal reforming. Ni/(rare earth phosphate), particularly Ni/(Gd, Cc, or ErPO4), has been found to be a new family of effective catalysts.

DOI： 10.1246/cl.2006.580

Other Link： http://orcid.org/0000-0003-1774-1537

Anaerobic oxidation of isobutane II. Catalysis by Mg-V complex oxides Reviewed

Y Takita, Q Xia, K Kikutani, K Soda, H Takami, H Nishiguchi, K Nagaoka

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL Vol. 248 ( 1-2 ) page： 61 - 69 2006.4

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

Anaerobic oxidation of isobutane was studied using MgV2O6, Mg2V2O7 and Mg3V2O8. Isobutene, a small amount of COx, and trace amount of oxygen containing compounds were formed. CO2 Was formed mainly at the beginning of the reaction and decreased with reaction time. Catalytic activity of Mg2V2O7 was slightly higher than that of MgV2O6 but the CO., formation over MgV2O6 was more than over Mg2V2O7. Mg3V2O8 was the least active. Therefore, Mg2V2O7 is the most suitable for oxidative hydrogenation of isobutane under the anaerobic reaction conditions. The equilibration between O-16(2) and O-18(2) over MgV2O6 was faster than over Mg2V2O7 or Mg3V2O8 at 673 K. The rate of equilibration between O-18(2) and lattice oxygen over MgV2O6 was similar to that over Mg2V2O7, which was faster than over Mg3V2O8. Highest yield of isobutene formation over Mg2V2O7 would come from the character of Mg2V2O7, in which mobility of the lattice oxygen is great but surface reaction of isobutane was not so fast. Higher activity for isobutene formation may come from the nature Of Mg2V2O7, of which mobility of the lattice oxygen is great but surface reaction of isobutane was not so much fast. Mn, Cr, Fe, Ni and Co can be introduced into Mg2V2O7 to give a single phase. Substitution of Co, Cu and Cr for Mg increased the activity Of Mg2V2O7 for isobutane oxidation and substitution of Ni and Mn scarcely affected the activity but substitution of Fe and Zn decreased the activity. Substitution of all the metal ions slightly increased the isobutene selectivity. MgO, MgV2O4 and Mg3V2O8 were observed in the sample after the anaerobic oxidation of isobutane. Cu containing catalyst was reduced to give Cu metal. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2005.12.012

Other Link： http://orcid.org/0000-0003-1774-1537

Synthesis of highly active sulfated zirconia by sulfation with SO3 Reviewed

XB Li, K Nagaoka, R Olindo, JA Lercher

JOURNAL OF CATALYSIS Vol. 238 ( 1 ) page： 39 - 45 2006.2

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

Highly active sulfated zirconia (SZ) materials were prepared by sulfation of crystalline zirconia with gaseous SO3. This direct method circumvents the use of liquid sulfation agents, as well as a final calcination step. The amount of sulfur species retained by SO3-SZ samples was directly proportional to the fraction of monoclinic phase and the concentration of Bronsted acid sites. However, the catalytic activity in n-butane isomerization at 373 K was proportional to the concentration of labile chemisorbed SO3, most likely in the form of pyrosulfate species showing a characteristic IR band at 1404 cm(-1). Tetragonal zirconia favors the formation of these labile sulfur species, playing a key role in light alkane activation. (c) 2005 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2005.11.039

Other Link： http://orcid.org/0000-0003-1774-1537

Decomposition of chlorobenzene over phosphate and sulfate catalysts properties Reviewed

Y Takita, Y Sadatomi, H Nishiguchi, K Nagaoka

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN Vol. 79 ( 1 ) page： 145 - 148 2006.1

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

The catalytic conversion of chlorobenzene (CB) over some metal phosphates and sulfate was studied in the presence of water vapor and oxygen. The conversion of CB proceeded in the order of AlPO4, Zr-3(PO4)(4), CePO4-AlPO4, and La-2(SO3)(3) above 673 K. The major products were CO, CO2, and HCl. The reaction proceeded in the absence of water vapor; however, the activity was greatly reduced in the absence of oxygen. Even in the presence of oxygen, 30 mol % of water vapor inhibited the reaction. No intermediate hydration products were observed. There was no correlation between each of the catalytic activity, the acidity, and the concentration of the surface hydroxys of the catalysts. These results suggest that the essential reaction for CB conversion is oxidation. The specific surface area (SSA) of the catalysts was not changed during the CB conversion.

DOI： 10.1246/bcsj.79.145

Other Link： http://orcid.org/0000-0003-1774-1537

Oxidative dehydrogenation of isobutane to isobutene III reaction mechanism over CePO4 catalyst Reviewed

Y Takita, Qing, X, A Takami, H Nishiguchi, K Nagaoka

APPLIED CATALYSIS A-GENERAL Vol. 296 ( 1 ) page： 63 - 69 2005.11

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

Among rare earth phosphates, only CePO4 and LaPO4 exhibit very high activity for oxidative dehydrogenation (ODH) of isobutane. This phenomenon was studied in comparison with the corresponding oxides. Isobutene was formed over NdPO4, which was used as a representative of inactive phosphate catalysts, by simple dehydrogenation with 30-32% selectivity, C3H6 and CO2 were formed with a selectivity of 25-33% and 20-30%, respectively. Isobutene was obtained at a higher selectivity of 79-86% over CePO4 and LaPO4. No H, formation Suggests that the essential reaction wits the ODH of isobutane. In the oxidation over metal oxides, isobutene selectivity was relatively high: 60-70% over CeO2; however, the essential reaction was considered to be a simple dehydrogenation. Isobutene was formed at 40-47% selectivity, but simple dehydrogenation of isobutane would proceed over Nd2O3 and La2O3. La2O3, Nd2O3, and NdPO4 have only weak acidic sites. CeO2 has weak acidic sites and those with intermediate strength; LaPO4 and CePO4 have relatively strong acidic sites in addition to the weak acidic sites and those of intermediate strength. Oxidative dehydrogenation activity was correlated with strong acidic sites. ODH of isobutane occurred in the reaction between lattice oxygen of CePO4 and isobutane. Introduction of NH3 into the reaction system reduced both ODH of isobutane and CO2 formation; and stopping the NH3 supply led to a resumption of the activity, which suggests the participation of acidic sites. CePO4 catalyst contained 2% excess Ce to P; in the prepared CePO4 sample, Ce4+ was detected by XPS. We conclude that acidic sites and redox between Ce4+ and Ce3+ play important roles in the ODH of isobutane. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2005.07.049

Other Link： http://orcid.org/0000-0003-1774-1537

Oxidative activation of n-butane on sulfated zirconia Reviewed

XB Li, K Nagaoka, LJ Simon, R Olindo, JA Lercher, A Hofmann, J Sauer

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 127 ( 46 ) page： 16159 - 16166 2005.11

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

Catalytic activation and conversion of light alkanes by sulfated zirconia is unequivocally shown to be initiated by producing small concentrations of olefins. This occurs via stoichiometric oxidative dehydrogenation of butane by SO3 or pyrosulfate groups to butene (present mostly as alkoxy groups), water, and SO2. Thermal desorption and in situ IR spectroscopy have been used to determine all three reaction products. The concentration of butene formed determines both the catalytic activity of sulfated zirconia as well as the deactivation via formation of oligomers. The thermodynamics of the oxidative dehydrogenation of n-butane by different SZ surface structures has been examined by density functional (DFT) calculations. The calculations show that pyrosulfate or re-adsorbed SO3 species have the highest oxidizing ability.

DOI： 10.1021/ja054126d

Other Link： http://orcid.org/0000-0003-1774-1537

Synthesis of a thermally stable mesoporous aluminophosphate by using sodium aluminate as precursor Reviewed

LN Ho, S Yukushima, R Morikawa, N Asaka, H Nishiguchi, K Nagaoka, Y Takita

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS Vol. 268 ( 1-3 ) page： 40 - 44 2005.10

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

Sodium aluminate has been used as the aluminium precursor in the synthesis of mesoporous aluminophosphate where cetylpyridinium chloride (CTPC) was used as structure directing agent. Synthesis of the materials was performed in a broad range of pH from 3 to 10. The obtained materials were characterized by using XRD, TEM, ICP, nitrogen sorption isotherms, solid state NMR, TG-DTA and FTIR. The samples prepared at pH 5-8 were thermally stable up to 450 degrees C and presented specific surface areas in the range of 420-640 m(2) g(-1) after calcination for removal of the surfactant material. TEM image revealed the obtained mesoporous aluminophosphate possessed disordered porous structures. DH analysis derived from the adsorption branch showed that the average pore size of the sample was 2.6 nm in the 5-8 pH range. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2005.05.015

Other Link： http://orcid.org/0000-0003-1774-1537

Improved resistance against coke deposition of titania supported cobalt and nickel bimetallic catalysts for carbon dioxide reforming of methane Reviewed

K Takanabe, K Nagaoka, K Aika

CATALYSIS LETTERS Vol. 102 ( 3-4 ) page： 153 - 157 2005.8

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The catalytic behavior of bi-metallic Co-Ni/TiO2 catalysts for CO2 reforming of CH4 to synthesis gas was investigated under atmospheric pressure with a particular attention to carbon deposition. The catalysts with optimized Co/Ni ratios showed high catalytic stability towards the reaction with very little amount of deposited carbon at a wide range of reaction temperature (773-1123 K). The results suggest that adjusting of composition of the active metals (Co and Ni) can kinetically control the elementary steps (formation of carbon species and its removal by oxygen species) of CH4/CO2 reaction.

DOI： 10.1007/s10562-005-5848-4

Other Link： http://orcid.org/0000-0003-1774-1537

Mechanism of butane skeletal isomerization on sulfated zirconia Reviewed

XB Li, K Nagaoka, LJ Simon, R Olindo, JA Lercher

JOURNAL OF CATALYSIS Vol. 232 ( 2 ) page： 456 - 466 2005.6

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

A kinetic model of the skeletal isomerization of n-butane and isobutane on sulfated zirconia in the absence of Pt is presented. The skeletal isomerization of butane on sulfated zirconia has been shown to be initiated by oxidative dehydrogenation of the alkane. This is followed by the formation of alkoxy groups/carbenium ions at the surface, induced by strong Bronsted acid sites. The isomerization of the sec-butyl carbenium ion occurs mono-molecularly, as suggested by the 100% selectivity for isomerization extrapolated to zero conversion. With increasing conversion, the selectivity decreased linearly, leading to propane and pentanes up to 40% of conversion. The lower selectivity for isomerization is qualitatively explained by reactions of isobutene present in small concentrations in the reactor at higher conversions. Transient experiments show conclusively that the isomerization of the carbenium ion and not the hydride transfer from the alkane to the carbenium ion is the rate-determining step. (c) 2005 Published by Elsevier Inc.

DOI： 10.1016/j.jcat.2005.03.025

Other Link： http://orcid.org/0000-0003-1774-1537

Titania-supported cobalt and nickel bimetallic catalysts for carbon dioxide reforming of methane Reviewed

K Takanabe, K Nagaoka, K Nariai, K Aika

JOURNAL OF CATALYSIS Vol. 232 ( 2 ) page： 268 - 275 2005.6

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

Titania-supported cobalt and nickel bimetallic catalysts were investigated for CO2 reforming of methane to synthesis gas at 1023 K under ambient pressure. Bimetallic Co-Ni/TiO2 catalysts with an appropriate Co/Ni ratio showed highly stable activities without carbon deposition. Whereas the monometallic Co/TiO2 catalyst deactivated rapidly because of the oxidation of metal, 10 mol% substitution of nickel for cobalt suppressed the oxidation of metal, providing a high catalytic stability. However, the catalysts with excess nickel content (> 80 mol%) underwent carbon formation. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed that a homogeneous alloy of cobalt and nickel was formed from bulk to the surface by the H-2 reduction. and the alloy was stabte during reforming The advantages of the bimetallic catalysts are high resistance to undesirable metal oxidation and coking, through the control of reactions between CH4 and CO2. (c) 2005 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2005.03.011

Other Link： http://orcid.org/0000-0003-1774-1537

Novel tough catalyst supports for reactions involving HF Reviewed

Y Takita, T Ohkuma, H Nishiguchi, K Nagaoka, T Nakajo

APPLIED CATALYSIS A-GENERAL Vol. 283 ( 1-2 ) page： 47 - 52 2005.4

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

Metal fluorides are more stable than metals and metal oxides; therefore, no oxides can be applied as catalyst supports for the reactions in which hydrogen fluoride is involved. The authors observed that metal phosphates are not reactive to HF at higher reaction temperatures such as 973 K. Hence, the decomposition of CCIF2CCIF2 was studied over Pt-supported SiO2, Al2O3, and AlPO4-based catalysts. Hydrodehalogenation proceeded and CHF2CCIF2 and C2H6 were formed as major products, small amounts of CHF2CHF2, CH2FCCIF2, CH2FCF3. and CH4 were also formed. Pt/SiO2 was the most active; however, SiO2 reacted with HF and the SiF4 formed sublimated. Following these, Al2O3 was the most active; however, it reacted with HF to form AlF3 and was deactivated. Similar hydrodehalogenation proceeded over Pt/AlPO4 and Pt/ (CePO4-AIPO(4)). The crystal structure of these catalysts did not change during the catalytic reaction, although the reduction of specific surface areas (SSA) was observed. Therefore, AlPO4 and Ce containing AlPO4 are suitable as catalyst supports in reactions in which HF is involved. XPS showed that the electronic effects of AlPO4 lie between that of SiO2 and Al2O3. A good linear relationship is found to exist between the initial reaction rates per unit Surface area of Pt metal supported on the supports and the binding energy of supported Pt. This suggests that the more cationic the Pt. the more easily it could abstract Cl- from CCIF2CCIF2. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2004.12.033

Other Link： http://orcid.org/0000-0003-1774-1537

Oxidation of isobutane over complex oxides containing V, Nb, Ta, and Mo under aerobic and anaerobic reaction conditions Reviewed

Y Takita, K Kikutani, C Xia, H Takami, K Nagaoka

APPLIED CATALYSIS A-GENERAL Vol. 283 ( 1-2 ) page： 209 - 216 2005.4

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

Isobutane oxidation over sin-le metal oxides of V, Nb, Ta, and Mo and over their complex oxides was studied. The most active was V2O5, while medium activity was shown by LaVO4, BiVO4, CaV2O6, Ta2O5, TaV2O6, ZnNb2O6, Nb2PO5, MgV2O6, YVO4, Cu2V2O7, MoO3 and MnNb2O5. The less active oxides were Na2MoO4 and Ag2MoO4. lsobutane was oxidized mainly to isobutene and COx. but isobutene selectivity was generally lower than 50% below 673 K. Relatively high isobutene selectivity was shown by MgTa2O6, TaV2O6, and ZnNb2O6. Methacroleine was only obtained over MoO3 and methanol was formed only over V2O5 and Cu2V2O7. Acetic acid was formed over certain V-containing oxides. No oxygen-containing products were formed over Nb- and Ta-containing oxides. On a unit surface area basis, Nb2O5 and Ta2O5 have higher oxidizing activity than V2O5 and MoO3.
Isobutane oxidation was studied in the absence of gaseous O-2 over MV2-type complex oxides. Catalytic activity was determined as follows: CuV2O6 >> CoV2O6 > MgV2O6 > ZnV2O6 >> ZrV2O7 > CaV(2)O(6)center dot MgV2O6 is the most selective for isobutene formation. Combination to easily redoxable metal ions tends to accelerate the deep oxidation process. There may be a threshold for the initial reaction rate of lattice oxygen per unit surface area for selective isobutene formation. Selective isobutene formation continued until a reduction of MgV2O6 by least 4.5%, had finished and the reduced catalyst was recovered by the calcination at 773 K. Selective formation of isobutene made it possible to combine oxidations of isobutane with MgV2O6 and with the oxidations of reduced catalysts. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2005.01.008

Other Link： http://orcid.org/0000-0003-1774-1537

Influence of reduction temperature on the catalytic behavior of Co/TiO2 catalysts for CH4/CO2 reforming and its relation with titania bulk crystal structure Reviewed

Takanabe K, Nagaoka K, Nariai K, Aika K

JOURNAL OF CATALYSIS Vol. 230 ( 1 ) page： 75 - 85 2005.2

Interaction between sulfated zirconia and alkanes: prerequisites for active sites - formation and stability of reaction intermediates Reviewed

Li XB, Nagaoka K, Simon LJ, Lercher JA, Wrabetz S, Jentoft FC, Breitkopf C, Matysik S, Papp H

JOURNAL OF CATALYSIS Vol. 230 ( 1 ) page： 214 - 225 2005.2

Methane autothermal reforming with and without ethane over mono- and bimetal catalysts prepared from hydrotalcite precursors Reviewed

K Nagaoka, A Jentys, JA Lercher

JOURNAL OF CATALYSIS Vol. 229 ( 1 ) page： 185 - 196 2005.1

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

Autothermal reforming of methane (in the presence or absence of ethane) over Ni and/or Rh catalysts prepared from hydrotalcites is reported. Surface and bulk structures of the reduced supported metal catalysts were characterized by various physicochemical techniques. XANES and EXAFS at the Ni and Rh K-edges indicate that the reduction of Ni2+ and Rh3+ in the support matrix with H-2 was incomplete for all catalysts. NiRh alloy particles are formed in NiRh/MgAl. IR spectra of adsorbed CO indicate that the surface of the NiRh alloy particles is enriched in Ni. All catalysts hardly catalyzed coke formation during CH4 autothermal reforming. The surface concentration of reduced Ni was critical for the catalytic activity, i.e., the catalytic activity decreased in the order NiRh/MgAl > Ni/MgAl-2 > Rh/MgAl-1. However, Ni/MgAl-2 lost its activity, when cycling between 1073 and 773 K at very high space velocities (1.2 x 10(4) l/(h g)) through oxidation of metallic Ni. In contrast, NiRh/MgAl was relatively stable, while Rh/MgAl-1 did not deactivate. The enhanced stability of NiRh/MgAl by Rh against oxidation is attributed to H-2 spillover from Rh in the NiRh alloy as well as to its high activity (larger fraction with reducing atmosphere). The activity of all catalysts in converting hydrocarbons increased in the presence of ethane, with ethane showing a high tendency to react preferentially. Ethane could be converted completely in the presence of partly converted methane. NiRh/MgAl and Rh/MgAl-1 showed stable activity at 1073 and 773 K, while Ni/MgAl-2 gradually deactivated at 773 K. The deactivation attributed to Ni oxidation was reduced by addition of C2H6. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2004.10.006

Other Link： http://orcid.org/0000-0003-1774-1537

Improvement of Pt/ZrO2 by CeO2 for high pressure CH4/CO2 reforming Reviewed

Nagaoka K, Seshan K, Takanabe K, Aika K

CATALYSIS LETTERS Vol. 99 ( 1-2 ) page： 97 - 100 2005.1

Labile sulfates as key components in active sulfated zirconia for n-butane isomerization at low temperatures Reviewed

XB Li, K Nagaoka, JA Lercher

JOURNAL OF CATALYSIS Vol. 227 ( 1 ) page： 130 - 137 2004.10

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

A wide variety of sulfate species exists on sulfated zirconia and many of these species have been connected to the catalytic performance. Some of these groups show strong interactions with polar molecules, indicating that they may play a role for the catalytic properties. In order to differentiate between these groups and to explore the role of labile soluble sulfate for n-butane skeletal isomerization, active sulfated zirconia was washed with water. Water washing removed around 40% of the sulfate species and led to a catalyst inactive for the alkane isomerization. This indicates that the labile sulfate plays a key role for the catalysis. The water-soluble fraction of the sulfate exists as highly covalent sulfate species characterized by an S=O vibration between 1390 and 1410 cm(-1) on the activated sulfated zirconia. Bronsted acid sites related to the sulfate groups are shown to be indispensable for activating n-butane, while Lewis acid sites do not directly participate in the alkane conversion catalysis. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcat.2004.07.003

Other Link： http://orcid.org/0000-0003-1774-1537

Modification of Co/TiO2 for dry reforming of methane at 2 MPa by Pt, Ru or Ni Reviewed

K Nagaoka, K Takanabe, K Aika

APPLIED CATALYSIS A-GENERAL Vol. 268 ( 1-2 ) page： 151 - 158 2004.8

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

Influences of an addition of trace amounts of Pt (Pt/Co = 0.005-0.05 in atomic ratio) or Ru (Ru/Co = 0.01-0.05) and of replacement of Co by Ni (Ni:Co = 1:99-100:0) to 0.5 wt.% Co/TiO2 have been investigated for the dry reforming of methane at 2MPa. Co/TiO2 reduced at 1123 K showed slow deactivation due to oxidation of Co. The addition of noble metals improved the catalytic stability of Co/TiO, drastically. The strong resistant nature of Co/TiO, to coke deposition was also retained by the catalysts. TPR revealed that noble metals improved the reducibility of cobalt oxide. The replacement of Co by a small amount of Ni also enhanced the catalytic stability of Co/TiO2, but replacement by an excess of Ni resulted in the decrease of catalytic stability because of coking. CoNi/TiO2 with an optimum Co:Ni ratio of 90:10 presented high stability with only an insignificant amount of coke deposition under 2 MPa, where coke deposition is highly favorable. (C) 2004 Published by Elsevier B.V.

DOI： 10.1016/j.apcata.2004.03.029

Other Link： http://orcid.org/0000-0003-1774-1537

Co/TiO<inf>2</inf>catalyst for high pressure dry reforming of methane and its modification by other metals Reviewed

Katsutoshi Nagaoka, Kazuhiro Takanabe, Ken Ichi Aika, Ken Ichi Aika

Studies in Surface Science and Catalysis Vol. 147 page： 187-192 2004.1

Language：English Publishing type：Research paper (scientific journal)

Catalytic behaviour of 0.5wt%Co/TiO2, prepared from TiO2containing only anatase phase, in CH4/CO2reforming at 2 MPa was strongly affected by reduction temperature. Co/TiO2reduced at relatively lower temperatures (<1123 K) lost all of its activity at the beginning of the reaction, whereas the catalyst reduced at higher temperatures (1123 K) showed relatively stable activity with only a slight amount of deposited coke. However, the latter catalyst lost all of activities at a higher space velocity after the reaction for 20 h, mainly due to oxidation of metallic Co. The addition of trace amounts of noble metals (Pt or Ru) improved the catalytic stability drastically by retarding the oxidation. It was confirmed that the strong resistant nature of Co/TiO2to coke deposition was retained after the addition of the noble metals.

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