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Journal Articles

Fabrication, permeation, and corrosion stability measurements of silica membranes for HI decomposition in the thermochemical iodine-sulfur process

Myagmarjav, O.; Shibata, Ai*; Tanaka, Nobuyuki; Noguchi, Hiroki; Kubo, Shinji; Nomura, Mikihiro*; Takegami, Hiroaki

International Journal of Hydrogen Energy, 46(56), p.28435 - 28449, 2021/08

 Times Cited Count:2 Percentile:17.53(Chemistry, Physical)

Journal Articles

Development of a membrane reactor with a closed-end silica membrane for nuclear-heated hydrogen production

Myagmarjav, O.; Tanaka, Nobuyuki; Nomura, Mikihiro*; Noguchi, Hiroki; Imai, Yoshiyuki; Kamiji, Yu; Kubo, Shinji; Takegami, Hiroaki

Progress in Nuclear Energy, 137, p.103772_1 - 103772_7, 2021/07

 Times Cited Count:6 Percentile:85.19(Nuclear Science & Technology)

Journal Articles

Comparison of experimental and simulation results on catalytic HI decomposition in a silica-based ceramic membrane reactor

Myagmarjav, O.; Tanaka, Nobuyuki; Nomura, Mikihiro*; Kubo, Shinji

International Journal of Hydrogen Energy, 44(59), p.30832 - 30839, 2019/11

 Times Cited Count:10 Percentile:39.33(Chemistry, Physical)

Journal Articles

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

 Times Cited Count:16 Percentile:56.51(Chemistry, Physical)

Journal Articles

Module design of silica membrane reactor for hydrogen production via thermochemical IS process

Myagmarjav, O.; Tanaka, Nobuyuki; Nomura, Mikihiro*; Kubo, Shinji

International Journal of Hydrogen Energy, 44(21), p.10207 - 10217, 2019/04

 Times Cited Count:14 Percentile:51.64(Chemistry, Physical)

Journal Articles

Hydrogen production tests by hydrogen iodide decomposition membrane reactor equipped with silica-based ceramics membrane

Myagmarjav, O.; Tanaka, Nobuyuki; Nomura, Mikihiro*; Kubo, Shinji

International Journal of Hydrogen Energy, 42(49), p.29091 - 29100, 2017/12

 Times Cited Count:19 Percentile:53.37(Chemistry, Physical)

The catalytic decomposition of hydrogen iodide in a membrane reactor using silica membranes derived from hexyltrimethoxysilane (HTMOS) was investigated for the production of hydrogen in the thermochemical water splitting iodine-sulfur process. The silica membranes were prepared by counter-diffusion chemical vapor deposition using porous alumina support tubes in both the absence and presence of a $$gamma$$-alumina layer. The silica membranes formed on $$gamma$$-alumina-coated $$alpha$$-alumina tubes displayed a higher H$$_{2}$$ permeance than that formed directly on an $$alpha$$-alumina tube. A silica membrane based on a 1.5 $$mu$$m-thick $$gamma$$-alumina layer fabricated under deposition conditions of 450$$^{circ}$$C, 1200 s, and a N$$_{2}$$ carrier gas velocity of 0.044 m s$$^{-1}$$ exhibited a high H$$_{2}$$ permeance of 9.4 $$times$$ 10$$^{-7}$$ mol Pa$$^{-1}$$ m$$^{-2}$$ s$$^{-1}$$ while maintaining an H$$_{2}$$/N$$_{2}$$ selectivity of over 80.0. The performance of a membrane reactor based on an HTMOS-derived silica membrane was evaluated at 400$$^{circ}$$C by measuring the HI conversion and H$$_{2}$$ flow rates. The conversion was approximately 0.48 when the HI flow rate was 9.7 mL min$$^{-1}$$.

Journal Articles

Preparation of an H$$_{2}$$-permselective silica membrane for the separation of H$$_{2}$$ from the hydrogen iodide decomposition reaction in the iodine-sulfur process

Myagmarjav, O.; Ikeda, Ayumi*; Tanaka, Nobuyuki; Kubo, Shinji; Nomura, Mikihiro*

International Journal of Hydrogen Energy, 42(9), p.6012 - 6023, 2017/03

 Times Cited Count:19 Percentile:53.37(Chemistry, Physical)

Journal Articles

Elucidation of the morphology of the hydrocarbon multi-block copolymer electrolyte membranes for proton exchange fuel cells

Zhao, Y.; Yoshida, Miru*; Oshima, Tatsuya*; Koizumi, Satoshi*; Rikukawa, Masahiro*; Szekely, N.*; Radulescu, A.*; Richter, D.*

Polymer, 86, p.157 - 167, 2016/03

 Times Cited Count:13 Percentile:45.06(Polymer Science)

Journal Articles

Imidazolium-based anion exchange membranes for alkaline anion fuel cells; Elucidation of the morphology and the interplay between the morphology and properties

Zhao, Y.; Yoshimura, Kimio; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Koizumi, Satoshi*; Szekely, N.*; Radulescu, A.*; Richter, D.*; Maekawa, Yasunari

Soft Matter, 12(5), p.1567 - 1578, 2016/02

 Times Cited Count:25 Percentile:80.57(Chemistry, Physical)

Journal Articles

Poly(ether ether ketone) (PEEK)-based graft-type polymer electrolyte membranes having high crystallinity for high conducting and mechanical properties under various humidified conditions

Hamada, Takashi; Hasegawa, Shin; Fukasawa, Hideyuki*; Sawada, Shinichi; Koshikawa, Hiroshi; Miyashita, Atsumi; Maekawa, Yasunari

Journal of Materials Chemistry A, 3(42), p.20983 - 20991, 2015/11

 Times Cited Count:32 Percentile:71.23(Chemistry, Physical)

no abstracts in English

Journal Articles

Imidazolium cation based anion-conducting electrolyte membranes prepared by radiation induced grafting for direct hydrazine hydrate fuel cells

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Journal of the Electrochemical Society, 161(9), p.F889 - F893, 2014/06

 Times Cited Count:20 Percentile:62.35(Electrochemistry)

Graft-type anion-conducting electrolyte membranes (AEMs) with imidazolium cations on graft polymers were synthesized through radiation-induced graft polymerization of ${it N}$-vinylimidazole (NVIm) on poly(ethylene-co-tetrafluoroethylene) (ETFE) films, followed by ${it N}$-propylation and ion-exchange reactions. The ${it N}$-propylation proceeded quantitatively, whereas the ion-exchange reactions in 1 M KOH at 60$$^{circ}$$C were accompanied by partial $$beta$$-elimination of the imidazolium cations(AEM2), which exhibited an ion-exchange capacity (IEC) of 0.85 mmol g$$^{-1}$$ and ionic conductivity of 10 mS cm$$^{-1}$$. AEM2 showed alkaline stability at 60$$^{circ}$$C but it gradually degraded at 80$$^{circ}$$C for ca. 150 h. The copolymer-type AEM (AEM3) with an IEC of 1.20 mmol g$$^{-1}$$ was prepared through the copolymerization of NVIm with styrene on ETFE films, followed by the same ${it N}$-propylation and ion-exchange reactions. AEM3 was shown higher alkaline durability in 1 M KOH at 80$$^{circ}$$C. As a result, it exhibited higher conductivity ($$>$$10 mS cm$$^{-1}$$) for 250 h. Therefore, alkylimidazolium cations in copolymer grafts are a promising anion conducting group for alkaline-durable AEMs. A maximum power density of 75 mW cm$$^{-2}$$ is obtained for AEM3 in a direct hydrazine hydrate fuel cell.

Journal Articles

Effect of crosslinkers on the preparation and properties of ETFE-based radiation-grafted polymer electrolyte membranes

Chen, J.; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

Journal of Applied Polymer Science, 100(6), p.4565 - 4574, 2006/06

 Times Cited Count:44 Percentile:76.61(Polymer Science)

This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2-bis(p,p-vinylphenyl)ethane (BVPE) and triallyl cyanurate (TAC) crosslinked poly(ethylene-co-tetrafluoroethylene) (ETFE)-based radiation-grafted membranes, which were prepared by radiation grafting of p-methylstyrene (MeSt) onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity and thermal/chemical stability of the resulting polymer electrolyte membranes was investigated in detail. Introducing crosslink structure into the radiation-grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation-grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation-grafted membranes show significantly higher chemical stability characterized in the 3% H$$_{2}$$O$$_{2}$$ at 50$$^{circ}$$C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation-grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers.

Journal Articles

Feasibility study on the blanket tritium recovery system using the palladium membrane diffuser

Kawamura, Yoshinori; Enoeda, Mikio; Yamanishi, Toshihiko; Nishi, Masataka

Fusion Engineering and Design, 81(1-7), p.809 - 814, 2006/02

 Times Cited Count:14 Percentile:69.06(Nuclear Science & Technology)

Tritium bred in the solid breeder blanket of a fusion reactor is extracted by passing of a helium sweep gas. Tritium is separated from sweep gas at the blanket tritium recovery system. Palladium membrane diffuser is one of the applicable processes for the blanket tritium recovery system. It is usually applied for hydrogen purification system such as TEP in ITER. However, it has been reported that the rate controlling step changes at lower hydrogen pressure such as the blanket sweep gas condition, and discussion about application for the blanket sweep gas condition is not enough. Recently, conceptual design of the demonstration reactor, named "DEMO2001", has been proposed from JAERI. In this report, the application of the Pd diffuser for the blanket sweep gas condition is discussed based on the condition of DEMO 2001.

Journal Articles

Improvement of chemical stability of polymer electrolyte fuel cell membranes by grafting of new substituted styrene monomers into ETFE films

Chen, J.; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

Journal of Materials Science, 41(4), p.1289 - 1292, 2006/02

 Times Cited Count:22 Percentile:59.29(Materials Science, Multidisciplinary)

The MeSt/tBuSt/DVB-grafted polymer electrolyte membrane showed a high performance for the fuel cell applications. The tBuSt contributed the high chemical stability while the MeSt contributed the high conductivity to the resulted membrane. The DVB crosslinker in the membrane further improved the chemical stability. The new polymer electrolyte membrane with a degree of grafting of 36% showed proton conductivity as high as the Gore-Select membrane, and the durability time was about 3 times longer than that of the traditional styrene/DVB-grafted one. Therefore, the MeSt/tBuSt/DVB-grafted polymer electrolyte membrane was more possible to be used for the fuel cells.

Journal Articles

Preparation and characterization of chemically stable polymer electrolyte membranes by radiation-induced graft copolymerization of four monomers into ETFE films

Chen, J.; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

Journal of Membrane Science, 269(1-2), p.194 - 204, 2006/02

 Times Cited Count:139 Percentile:96.33(Engineering, Chemical)

To develop a highly chemically stable polymer electrolyte membrane for application in a direct methanol fuel cell (DMFC), four styrene derivative monomers, m,p-methylstyrene (MeSt), p-tert-butylstyrene (tBuSt), divinylbenzene (DVB) and bis(p,p-vinyl phenyl) ethane (BVPE) were graft copolymerized into poly(ethylene-co-tetrafluoroethylene) (ETFE) films followed by sulfonation and hydrolysis. The latter two monomers were used as crosslinkers. The graft copolymerization was carried out by the $$gamma$$-ray preirradiation method. The influence of the preirradiation dose and the grafting kinetics were investigated in detail. Sulfonation of the grafted ETFE films was performed in a chlorosulfonic acid solution, by which the sulfonation ratio reached about 90%. The newly obtained membrane possesses significantly higher chemical stability than the traditional styrene/DVB-grafted membrane and six times lower methanol permeability compared to the Nafion 112 membrane. Therefore, this study reveals the possibility of the developed inexpensive four monomers-grafted membranes, which could provide an attractive alternative as a substitute for the expensive Nafion membranes for DMFC applications.

Journal Articles

Proton conduction properties of crosslinked PTFE electrolyte membranes with different graft-chain structures

Sawada, Shinichi; Yamaki, Tetsuya; Asano, Masaharu; Terai, Takayuki*; Yoshida, Masaru

Transactions of the Materials Research Society of Japan, 30(4), p.943 - 946, 2005/12

We synthesized crosslinked-polytetrafluoroethylene (PTFE) electrolyte membranes by a radiation grafting technique under different conditions, and then investigated their proton conduction properties at controlled temperatures and relative humidities (R.H.) by an AC impedance method. The density and length of graft chains were controlled by varying the pre-irradiation dose and grafting time, respectively. When the pre-irradiation dose was fixed at 15 kGy to make the graft chains an uniform density, the elongation of the graft chain increased the ion exchange capacity (IEC), there by enhancing their proton conductivity. The membrane with an IEC of 2.8 meq/g possessed the maximum conductivity reaching 0.20 S/cm at 80 $$^{circ}$$C and R.H. 95%. At almost the same IEC, membranes with more and shorter graft chains showed higher conductivity than those with less and longer chains. This result was probably related to the different structures of hydrophilic domains as proton-conducting pathways.

Journal Articles

Preparation of an extractant-impregnated porous membrane for the high-speed separation of a metal ion

Asai, Shiho; Watanabe, Kazuo; Sugo, Takanobu*; Saito, Kyoichi*

Journal of Chromatography A, 1094(1-2), p.158 - 164, 2005/11

 Times Cited Count:23 Percentile:56.29(Biochemical Research Methods)

The analysis of radioactive species in radioactive wastes is essential to the safe and economical disposal of such wastes. Among radioactive species, alpha- and beta-emitting nuclides should be purified prior to various radiometric determinations. To overcome the disadvantages of the conventional separation techniques, we have proposed functional porous hollow-fiber membranes that achieve a high speed operation assisted by convective flow. Stable immobilization in aqueous media is ensured by the hydrophobic interaction between the hydrophobic moiety of the extractant and octadecyl part of octadecylamino group. In this study, HDEHP, which shows the selectivity for rare earth elements, such as yttrium, was immobilized onto the porous membrane. The amount of immobilized HDEHP increased with increasing molar conversion. This can be explained by the fact that an increase in the C$$_{18}$$NH group allows the polymer brush to extend itself due to electrostatic repulsion originating from the amino part of the C$$_{18}$$NH group.

Journal Articles

Component tests on research and development of HTTR hydrogen production systems

Ohashi, Hirofumi; Nishihara, Tetsuo; Takeda, Tetsuaki; Inagaki, Yoshiyuki

Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13) (CD-ROM), 8 Pages, 2005/05

A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) is being designed to be able to produce hydrogen using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world, hence an mock-up model test is planned to carry out prior to the demonstration test of the HTTR hydrogen production system. In parallel to the mock-up model test, the following tests as an essential problem, a corrosion test of a reforming tube, a permeation test of hydrogen isotopes through a heat exchanger tube, an integrity test of a high-temperature isolation valve, and a performance test of a hydrogen permselective membrane are carried out to obtain detailed data for a safety review and development of analytical codes. This paper describes the present status of the component tests on the R&D of the HTTR hydrogen production system.

Journal Articles

Preparation of proton exchange membranes based on crosslinked polytetrafluoroethylene for fuel cell applications

Yamaki, Tetsuya; Kobayashi, Kazuhiro; Asano, Masaharu; Kubota, Hitoshi*; Yoshida, Masaru

Polymer, 45(19), p.6569 - 6573, 2004/09

 Times Cited Count:56 Percentile:83.15(Polymer Science)

We prepared proton exchange membranes by the $$gamma$$-ray-induced post grafting of styrene into crosslinked polytetrafluoroethylene (PTFE) films and subsequent sulfonation. The degree of grafting was controlled in the range of 7-75% by the crosslinking density of the PTFE matrix as well as the grafting conditions. Under our preparation conditions, the films at the grafting yield of $$geq$$30% were found to produce ion exchange membranes with a homogeneous distribution of sulfonic acid groups. The resulting membranes showed a large ion exchange capacity up to 2.9 meq g$$^{-1}$$, which exceeded the performance of commercially-available perfluorosulfonic acid films such as Nafion; nevertheless, they appeared to be dimensionally stable in water. These should undoubtedly result from the use of the crosslinked PTFE films as graft substrates and make our ion exchange membranes promising for applications to polymer electrolyte fuel cells.

Journal Articles

Role of UV light illumination and DMF soaking in production of PET ion track membranes

Zhu, Z.; Maekawa, Yasunari; Koshikawa, Hiroshi; Suzuki, Yasuyuki; Yonezawa, Noriyuki*; Yoshida, Masaru

Nuclear Instruments and Methods in Physics Research B, 217(3), p.449 - 456, 2004/05

 Times Cited Count:20 Percentile:77.1(Instruments & Instrumentation)

The pretreatment effects using UV light illumination and DMF soaking on bulk and track etching rates of PET films were investigated. The wavelength of illuminated UV light plays an important role in sensitizing track etching. Illumination with the light at wavelengths longer than 320nm showed strong enhancement in the track etching rates without influence on the bulk etching rates, whereas light with the wavelengths lower than 320nm causes large enhancement in both track and bulk etching rates even in the interior of the material. The track etching rate is found to be not constant along ion tracks, which is attributed to the inhomogeneous distribution of reactive chemical species induced during post-UV light illumination. Furthermore, the DMF soaking of PET after UV light illumination can enhance the etching sensitivity of the track by more than 100 times. The phenomenon is attributed to the high diffusion of organic solution along tracks after UV light illumination.

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