Faculty Profiles - NAKANISHI Kazuki

Papers - NAKANISHI Kazuki

Division display 201 - 220 of about 412 ／ All the affair displays >>

Preparation of Hierarchically Porous Nanocrystalline CaTiO3, SrTiO3 and BaTiO3 Perovskite Monoliths Reviewed

Olim Ruzimuradov, George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakanishi

JOURNAL OF THE AMERICAN CERAMIC SOCIETY Vol. 94 ( 10 ) page： 3335 - 3339 2011.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

Hierarchically porous nanocrystalline CaTiO3, SrTiO3, and BaTiO3 ceramics have been produced by impregnating corresponding alkaline-earth metal ions into preformed macroporous TiO2 monoliths in a solution containing urea, followed by calcination. The macroporous TiO2 had been obtained via the sol-gel process accompanied by phase separation utilizing a chelating agent, ethyl acetylacetonate (EtAcAc), together with mineral salt and ammonium chloride, to decrease the reactivity of titanium alkoxide. Formations of CaCO3, SrCO3, and BaCO3 on the surface of TiO2 monoliths are promoted by CO2 generated by the concurrent two processes during impregnation; hydrolysis, and decarbonation of the chelating agent EtAcAc, and hydrolysis of urea at 60 degrees C. The latter also raises pH of the impregnating solution which further promotes the mineralization of the carbonate salts. Calcination of the resultant monolithic composite of metal carbonate/TiO2 allows the crystallization of metal titanate. The addition of urea to the impregnating solution is found to be an effective strategy for the formation of perovskite monoliths by the impregnation process. This study provides a versatile approach to the preparation of hierarchically porous titania-based perovskites.

DOI： 10.1111/j.1551-2916.2011.04613.x

Fabrication of highly crosslinked methacrylate-based polymer monoliths with well-defined macropores via living radical polymerization Reviewed Open Access

George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakanishi, Shigeru Yamago

POLYMER Vol. 52 ( 21 ) page： 4644 - 4647 2011.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

Rigid methacrylate-based polymer monoliths with well-defined macropores have been synthesized from glycerol 1,3-dimethacrylate (GDMA) and trimethylolpropane trimethacrylate (Trim) by organotellurium-mediated living radical polymerization. In each system, poly(ethylene oxide) induced spinodal decomposition with the progress of polymerization of COMA or Trim. Well-defined macroporous structure can be tailored by fixing the bicontinuous structure by the sol gel transition. Both polymer monoliths possessed macropores with narrow size distributions and the macropore size can be controlled simply by varying the amount of poly(ethylene oxide). Starting from GDMA, polymer monoliths with unimodal macropores can be obtained due to the collapse of micro- and mesopores, which were originally embedded in macropore skeletons, by large shrinkage during drying. In contrast, starting from Trim, the obtained polymer monoliths include not only macropores but also micro- and mesopores, which lead to high specific surface area (470 m(2) g(-1)), owing to the higher crosslinking density. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2011.08.028

Facile preparation of monolithic magnesium titanates with hierarchical porosity Reviewed Open Access

Olim N. Ruzimuradov, George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakanishi

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN Vol. 119 ( 1390 ) page： 440 - 444 2011.6

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

In this study, we for the first time came up with a facile approach to fabricate hierarchically porous nano-crystalline monolithic magnesium titanates (MgTi2O5/MgTiO3) by impregnating magnesium chloride into hierarchically porous TiO2 monolith in a solution containing urea followed by appropriate heat-treatment. The formation of porous MgTi2O5/MgTiO3 monolithic materials took place by the solid-state reaction between original TiO2 networks and precipitated MgCO3. The MgCO3 is precipitated within the TiO2 wet gel by the reaction between impregnated Mg2+ and CO2, which is produced by hydrolysis and decarbonation of chelating agent in the TiO2 wet gels and by the hydrolysis of urea at 60 degrees C. The resultant porous magnesium titanates retained narrow macropore size distribution centered at the diameter similar to 1 mu m. These porous monoliths produced by impregnation, a facile and the low-cost method, are expected to open various engineering applications owing to the low thermal expansion coefficients and high chemical and physical stabilities. (C)2011 The Ceramic Society of Japan. All rights reserved

DOI： 10.2109/jcersj2.119.440

Performance evaluation of long monolithic silica capillary columns in gradient liquid chromatography using peptide mixtures Reviewed

Hamed Eghbali, Koen Sandra, Frederik Detobel, Frederic Lynen, Kazuki Nakanishi, Pat Sandra, Gert Desmet

JOURNAL OF CHROMATOGRAPHY A Vol. 1218 ( 21 ) page： 3360 - 3366 2011.5

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

A systematic study is reported on the performance of long monolithic capillary columns in gradient mode. Using a commercial nano-LC system, reversed-phase peptide separations obtained through UV-detection were conducted. The chromatographic performance, in terms of conditional peak capacity and peak productivity, was investigated for different gradient times (varying between 90 and 1320 min) and different column lengths (0.25, 1, 2 and 4m) all originating from a single 4m long column. Peak capacities reaching values up to n = 10(3) were measured in case of the 4 m long column demonstrating the high potential of these long monoliths for the analysis of complex biological mixtures, amongst others. In addition, it was found that the different column fragments displayed similar flow resistance as well as consistent chromatographic performance in accordance with chromatographic theory indicating that the chromatographic bed of the original 4 m long column possessed a structural homogeneity over its entire length. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2010.10.045

Transition from transparent aerogels to hierarchically porous monoliths in polymethylsilsesquioxane sol-gel system Reviewed

Kazuyoshi Kanamori, Yasunori Kodera, Gen Hayase, Kazuki Nakanishi, Teiichi Hanada

JOURNAL OF COLLOID AND INTERFACE SCIENCE Vol. 357 ( 2 ) page： 336 - 344 2011.5

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

A transition from hierarchical pore structures (macro- and meso-pores) to uniform mesopores in monolithic polymethylsilsesquioxane (PMSQ CH(3)SiO(1.5)) gels has been investigated using a sol-gel system containing surfactant Pluronic F127. The precursor methyltrimethoxysilane (MTMS) undergoes an acid/base two-step reaction, in which hydrolysis and polycondensation proceed in acidic and basic aqueous media, respectively, as a one-pot reaction. Porous morphology is controlled by changing the concentration of F127. Sufficient concentrations of F127 inhibit the occurrence of micrometer-scale phase separation (spinodal decomposition) of hydrophobic PMSQ condensates and lead to well-defined mesoporous transparent aerogels with high specific pore volume as a result of the colloidal network formation in a large amount of solvent. Phase separation regulates well-defined macropores in the micrometer range on decreasing concentrations of F127. In the PMSQ-rich gelling domain formed by phase separation, the PMSQ colloidal network formation forms mesopores, leading to monolithic PMSQ gels with hierarchical macro- and meso-pore structures. Mesopores in these gels do not collapse on evaporative drying owing to the flexible networks and repulsive interactions of methyl groups in PMSQ. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2011.02.027

Monolithic silica rod columns for high-efficiency reversed-phase liquid chromatography Reviewed

Shota Miyazaki, Masakazu Takahashi, Masayoshi Ohira, Hiroyuki Terashima, Kei Morisato, Kazuki Nakanishi, Tohru Ikegami, Kanji Miyabe, Nobuo Tanaka

JOURNAL OF CHROMATOGRAPHY A Vol. 1218 ( 15 ) page： 1988 - 1994 2011.4

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

Chromatographic properties of a new type of monolithic silica rod columns were examined. Silica rod columns employed for the study were prepared from tetramethoxysilane, modified with octadecylsilyl moieties, and encased in a stainless-steel protective column with two polymer layers between the silica and the stainless-steel tubing. A 25 cm column provided up to 45,000 theoretical plates for aromatic hydrocarbons, or a minimum plate height of about 5.5 mu m, at optimum linear velocity of ca. 2.3 mm/s and back pressure of 7.5 MPa in an acetonitrile-water (80/20, v/v) mobile phase at 40 degrees C. The permeability of the column was similar to that of a column packed with 5 mu m particles, with K-F about 2.4 x 10(-14) m(2) (based on the superficial linear velocity of the mobile phase), while the plate height value equivalent to that of a column packed with 2.5 mu m particles. Generation of 80,000-120,000 theoretical plates was feasible with back pressure below 30 MPa by employing two or three 25 cm columns connected in series. The use of the long columns enabled facile generation of large numbers of theoretical plates in comparison with conventional monolithic silica columns or particulate columns. Kinetic plot analysis indicates that the monolithic columns operated at 30 MPa can provide faster separations than a column packed with totally porous 3-mu m particles operated at 40 MPa in a range where the number of theoretical plates (N) is greater than 50,000. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chroma.2010.11.032

Synthesis of hierarchical macro/mesoporous dicalcium phosphate monolith via epoxide-mediated sol-gel reaction from ionic precursors Reviewed

Yasuaki Tokudome, Akira Miyasaka, Kazuki Nakanishi, Teiichi Hanada

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY Vol. 57 ( 3 ) page： 269 - 278 2011.3

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

Starting from calcium chloride dihydrate (CaCl(2)center dot 2H(2)O), phosphoric acid (H(3)PO(4)), and poly(acrylic acid) (PAA) dissolved in a mixture of water and methanol (MeOH), dicalcium phosphate anhydrous (DCPA, CaHPO(4)) monoliths with co-continuous macropores and mesopores have been synthesized by the addition of propylene oxide. Macropores are formed as a result of phase separation, while mesopores as interstices between primary particles with the size of ca. 30 nm. Propylene oxide acts as a proton scavenger and leads to moderate pH increase in a reaction solution, which brings about gelation in several minutes. On the other hand, PAA acts as a crystal growth inhibitor as well as a phase separation inducer. The extensive crystal growth of DCPA is hindered by the addition of PAA which allows morphological control of the structure in micrometer range. Fourier transform infrared spectroscopy indicates that PAA and DCPA form composite via interaction between the carboxyl groups and the surface of crystals, and together form gel phase. The solvent phase, which is converted to macropores after evaporative drying, is mainly comprised of solvent. The degree of supersaturation in a reaction solution considerably influence on the crystallization process, and thereby, influences on the porous structure in nano- and micrometer ranges.

DOI： 10.1007/s10971-010-2184-y

Microscopic Characterizations Reviewed

Haruko Saito, Kazuyoshi Kanamori, Kazuki Nakanishi

Monolithic Silicas in Separation Science: Concepts, Syntheses, Characterization, Modeling and Applications, First Edition page： 81 - 102 2011.1

Synthesis Concepts and Preparation of Silica Monoliths Reviewed

Kazuki Nakanishi

Monolithic Silicas in Separation Science: Concepts, Syntheses, Characterization, Modeling and Applications, First Edition page： 11 - 33 2011.1

(3-Mercaptopropyl)trimethoxysilane-derived Porous Gel Monolith via Thioacetal Reaction-Assisted Sol-Gel Route Reviewed

S. Ito, M. Nishi, K. Kanamori, K. Nakanishi, T. Kurahashi, S. Matsubara, Y. Shimotsuma, K. Miura, K. Hirao

3RD INTERNATIONAL CONGRESS ON CERAMICS (ICC): NOVEL CHEMICAL PROCESSING SOL-GEL AND SOLUTION-BASED PROCESSING Vol. 18 ( SYMPOSIUM 2A ) 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD

Porous gel monolith was synthesized by reacting (3mercaptopropyl)trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless.

DOI： 10.1088/1757-899X/18/3/032003

Other Link： http://orcid.org/0000-0002-8069-4780

Pore Structure and Mechanical Properties of Poly(methylsilsesquioxane) Aerogels Reviewed

Kanamori K., Hayase G., Nakanishi K., Hanada T.

3RD INTERNATIONAL CONGRESS ON CERAMICS (ICC): NOVEL CHEMICAL PROCESSING SOL-GEL AND SOLUTION-BASED PROCESSING Vol. 18 2011

Hierarchically Porous Carbon Monoliths with High Surface Area from Bridged Poly(silsesquioxane) without Thermal Activation Process Reviewed Open Access

G. Hasegawa, K. Kanamori, K. Nakanishi, T. Hanada

3RD INTERNATIONAL CONGRESS ON CERAMICS (ICC): NOVEL CHEMICAL PROCESSING SOL-GEL AND SOLUTION-BASED PROCESSING Vol. 18 ( SYMPOSIUM 2A ) 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IOP PUBLISHING LTD

Hierarchically porous carbon monoliths with high specific surface areas have been fabricated by removing nano-sized silica phase from carbon/silica composites pyrolyzed from bridged poly(silsesquioxane). This activation method improves the homogeneity between inner and outer parts of the monoliths compared to the conventional thermal activation methods.

DOI： 10.1088/1757-899X/18/3/032005

Other Link： http://orcid.org/0000-0002-8069-4780

Synthesis of new flexible aerogels from MTMS/DMDMS via ambient pressure drying Reviewed Open Access

Gen Hayase, Kazuyoshi Kanamori, Kazuki Nakanishi, Teiichi Hanada

IOP Conference Series: Materials Science and Engineering Vol. 18 page： 032013 2011

Language：English Publishing type：Research paper (international conference proceedings)

Although silica aerogel is expected to be the material for energy savings, the lack of the strength prevents from commercial applications such as to low-density thermal insulators and acoustic absorbents. To improve mechanical properties, methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) are used as the co-precursor of aerogels in this study because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS/DMDMS-derived condensates, phase separation occurs, which must be suppressed in aqueous sol to obtain uniform and monolithic gel networks. We also employed surfactant n-hexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, various microstructures of pores are obtained. In the uniaxial compression test, the aerogel showed high flexibility and spring-back to the original shape after removing the stress.

DOI： 10.1088/1757-899X/18/3/032013

New flexible aerogels and xerogels derived from methyltrimethoxysilane/dimethyldimethoxysilane co-precursors Reviewed Open Access

Gen Hayase, Kazuyoshi Kanamori, Kazuki Nakanishi

JOURNAL OF MATERIALS CHEMISTRY Vol. 21 ( 43 ) page： 17077 - 17079 2011

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

We report new flexible "marshmallow-like'' aerogels and xerogels with a bendable feature from the methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) co-precursor systems. A 2-step acid/base sol-gel process and surfactant are employed to control the phase separation of the hydrophobic networks, which give porous monolithic gels. The obtained gels become softer and more flexible with increasing DMDMS fractions.

DOI： 10.1039/c1jm13664j

Monolithic electrode for electric double-layer capacitors based on macro/meso/microporous S-Containing activated carbon with high surface area Reviewed Open Access

George Hasegawa, Mami Aoki, Kazuyoshi Kanamori, Kazuki Nakanishi, Teiichi Hanada, Kiyoharu Tadanaga

JOURNAL OF MATERIALS CHEMISTRY Vol. 21 ( 7 ) page： 2060 - 2063 2011

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

Macro/meso/microporous carbon monoliths doped with sulfur have been prepared from sulfonated poly(divinylbenzene) networks followed by the activation with CO2 resulted in the activated carbon monoliths with high surface area of 2400 m(2) g(-1). The monolithic electrode of the activated carbon shows remarkably high specific capacitance (175 F g(-1) at 5 mV s(-1) and 206 F g(-1) at 0.5 A g(-1)).

DOI： 10.1039/c0jm03793a

In situ SAXS observation on metal-salt-derived alumina sol-gel system accompanied by phase separation Reviewed Open Access

Yasuaki Tokudome, Kazuki Nakanishi, Kazuyoshi Kanamori, Teiichi Hanada

JOURNAL OF COLLOID AND INTERFACE SCIENCE Vol. 352 ( 2 ) page： 303 - 308 2010.12

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

The structure formation process of hierarchically porous alumina gels has been investigated by in situ small angle X ray scattering (SAXS) The measurement was performed on the sol-gel solution containing aluminum chloride hexahydrate (AlCl(3) 6H(2)O) poly(ethylene oxide) (PEO) and propylene oxide (PO) The temporal divergence of scattering intensity in the low q regime was observed in the early stage of reaction indicating that the occurrence of spinodal-decomposition-type phase separation Detailed analysis of the SAXS profiles revealed that phase separation occurs between weakly branched polymenzing aluminum hydroxide (AH) and PEO Further progress of the condensation reaction forms phase-separated two phases that is AH rich phase and PEO rich phase with the micrometer range heterogeneity The growth and aggregation of primary particles occurs in the phase-separated AH-rich domain and there fore the addition of PEO influences on the structure in nanometer regime as well as micrometer regime The moderate stability of oligomeric species allows homogeneous condensation reaction parallel to phase separation and successful formation of hierarchically porous alumina gel (C) 2010 Elsevier Inc All rights reserved

DOI： 10.1016/j.jcis.2010.08.041

Synthesis of high-silica and low-silica zeolite monoliths with trimodal pores Reviewed

Yasuaki Tokudome, Kazuki Nakanishi, Sho Kosaka, Ayuta Kariya, Hironori Kaji, Teiichi Hanada

MICROPOROUS AND MESOPOROUS MATERIALS Vol. 132 ( 3 ) page： 538 - 542 2010.8

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

Using macroporous alumina as an aluminum source as well as structural support, high- and low-silica zeolites with trimodal pores have been fabricated in a monolithic form. Trimodally porous zeolites are obtained by the hydrothermal treatment of a monolithic alumina support impregnated with a mixture of AEROSIL 200, H(2)O, and sodium hydroxide or tetrapropylammonium hydroxide. The results of XRD measurement and (27)Al NMR analysis reveal the formation of zeolites and the incorporation of Al into zeolite frameworks in tetrahedrally-coordinated environment. Low-silica zeolites, such as PHI- and ANA-type zeolites are formed when sodium hydroxide is utilized as a base and a structure directing agent (SDA). On the other hand, MFI-type zeolites are crystallized from highly supersaturated solutions with the use of tetrapropylammonium hydroxide. High alkaline resistance of alumina support enables the choice of wide range of OH(-)/SiO(2) ratio, and moreover, the choice of desirable degree of supersaturation. As a result, the homogeneous crystallization of zeolites onto the alumina support has been successfully achieved. (C) 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.micromeso.2010.04.005

Sol-gel preparation of Ni/TiO2 catalysts with bimodal pore structures Reviewed

Masayuki Numata, Ryoji Takahashi, Ikuya Yamada, Kazuki Nakanishi, Satoshi Sato

APPLIED CATALYSIS A-GENERAL Vol. 383 ( 1-2 ) page： 66 - 72 2010.7

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

Ni/TiO2 with bimodal pore structure was prepared from nickel nitrate and titanium alkoxide by a sol-gel process under acidic conditions in the presence of formamide. The Ni/TiO2 has continuous macropores which are formed by fixing the transitional structure of phase separation. Although the addition of nickel nitrate in the sol-gel reaction of titanium alkoxide steeply decreases the phase separation tendency, the macropore size can be controlled by changing the composition of preparation. The Ni/TiO2 prepared by sol-gel has higher dispersion of Ni compared with that prepared by impregnation, and shows catalytic activity for the selective hydrogenation of crotonaldehyde: selectivity in the hydrogenation of C=C bond is much higher than that of C=O bond over sol-gel-derived Ni/TiO2. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2010.05.025

Fabrication of activated carbons with well-defined macropores derived from sulfonated poly(divinylbenzene) networks Reviewed

George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakanishi, Teiichi Hanada

CARBON Vol. 48 ( 6 ) page： 1757 - 1766 2010.5

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

Poly(divinylbenzene) (PDVB) monoliths with well-defined macropores that have been sulfonated and carbonized to obtain macroporous carbon monoliths. The original macroporous PDVB networks have been synthesized by living radical polymerization accompanied by spinodal decomposition. Sulfonation prevents polymer networks from large shrinkage and weight loss during carbonization by heat-treatment in an inert atmosphere. In the case of PDVB gels sulfonated at 120 degrees C using conc. H(2)SO(4), mesopores in the original skeletons as well as macropores are retained after carbonization. The obtained carbon monoliths are subsequently activated by CO(2), which resulted in activated carbons. The specific surface area of the obtained activated carbons reaches up to 2360 m(2) g(-1). (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2010.01.019

Other Link： http://orcid.org/0000-0002-8069-4780

A New Route to Monolithic Macroporous SiC/C Composites from Biphenylene-bridged Polysilsesquioxane Gels Reviewed

George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakamshi, Teiichi Hanada

CHEMISTRY OF MATERIALS Vol. 22 ( 8 ) page： 2541 - 2547 2010.4

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

Macroporous polysilsesquioxane monoliths have been synthesized from biphenylene-bridged alkoxysilane via the sol-gel transition and concurrent phase separation both induced by the polycondensation reaction The obtained polysilsesquioxane gels have been subsequently converted to macroporous SiC/C composites by the carbothermal reduction The SiC/C monoliths thus obtained involve no visible cracks and their porosity reaches as high as >90%. In addition, according to the nitrogen adsorption-desorption measurement results, the micro- and mesopore characteristics of the samples did not undergo a significant change during the carbothermal reduction and the SiC/C composites have large specific surface areas owing to the microporous carbons in the skeletons These composites therefore are more suitable for the applications to gas storage and catalyst supports compared to pure SiC.

DOI： 10.1021/cm9034616

　 PREV - NEXT 　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21