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1.
Kojiro Nakai Yasunori Oumi Haruyuki Horie Tsuneji Sano Hideaki Yoshitake 《Microporous and mesoporous materials》2007,100(1-3):328-339
Bromination and subsequent ethylenediamine substitution of the CC double bond in mesoporous ethylenesilica were carried out to explore the characteristics of this periodic mesoporous organosilica. The structures of the products (BrPMO and EDA–BrPMO, respectively) were analysed by IR, Br K-edge EXAFS and NMR spectroscopies, as well as X-ray diffraction and nitrogen adsorption. We showed (1) that the formulae of the two products that formed were [CHBrSiO1.5]0.45[CHSiO1.5]0.55 and [NH2CH2CH2NHCHSiO1.5]0.05 [CHBrSiO1.5]0.40[CHSiO1.5]0.55, respectively, (2) that the addition of Br2 at room temperature occurred on the CC double bonds with disturbing the framework structure, (3) that IR absorption band of CC bonds that reacted with Br2 is significantly different from that of inactive CC bond, (4) that the length of the C–Br bond was considerably longer than in conventional alkyl bromides, and (5) that a large proportion of the ν(C–Br) band remained at the same position in the IR absorption spectrum after the ethylenediamine (EDA) substitution, while a new ν(C–Br) absorption also appeared. The mechanisms of these reactions are discussed at both the micro and mesoscopic levels.
Arsenate adsorption on EDA–BrPMO, in which the EDA is directly bound to the “surface” of the mesopores, was compared with adsorption on EDA–Pr–PMO, which was prepared by the direct synthesis of 3-chloropropyl-functionalized mesoporous ethanesilica followed by the substitution of Cl with EDA. The strength of the adsorption, as measured with the distribution coefficient, was greater for the former adsorbent than the latter. The origin of this difference was attributed to the distance between amino group and the surface. 相似文献
2.
Ayman M. Atta Hamad A. Al-Lohedan Abdelrahman O. Ezzat Zuheir A. Issa Ahmad B. Oumi 《Journal of Polymer Research》2016,23(4):69
In this work, we aimed to develop a feasible method for in situ preparation of a magnetite ionic polymer nanocomposite at room temperature. For this purpose, acrylonitrile (AN) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers were copolymerized and crosslinked using different monomer mol ratios in the presence of N,N-methylenebisacrylamide (MBA) as crosslinker to produce ionic crosslinked polymers P(AN-co-AMPS. The nitrile groups were converted to amine amidoxime by reacting with hydroxylamine to increase the adsorption characteristics of the ionic polymers. The produced polymers were swelled in iron cations produced from the reaction of ferric chloride and potassium iodide, followed by reaction with an ammonium hydroxide solution to produce magnetite nano-polymer composites. We performed FT-IR and XRD analysis to determine the chemical and crystalline structures, and assessed the morphologies and magnetite content using SEM, TEM and TGA analyses. We investigated the adsorption capacity and mechanism of the prepared magnetite nano-composites as adsorbents for methylene blue, Co2+ and Ni2+ cations from water. 相似文献
3.
Toru Ikegami Tomotake Morita Shunichi Nakayama Hideyuki Negishi Dai Kitamoto Keiji Sakaki Yasunori Oumi Tsuneji Sano Kenji Haraya Hiroshi Yanagishita 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(8):1172-1177
BACKGROUND: Pervaporation employing ethanol‐permselective silicalite membranes as an alternative to distillation is a promising approach for refining low‐concentration bioethanol solutions. However, to make the separation process practicable, it is extremely important to avoid the problems caused by the adsorption of succinate on the membrane during the separation process. In this work, the pervaporation of an ethanol fermentation broth without succinate was investigated, as well as the influence of several fermentation broth nutrient components. RESULTS: Candida krusei IA‐1 produces an extremely low level of succinate. The decrease in permeate ethanol concentration through a silicone rubber‐coated silicalite membrane during the separation of low‐succinate C. krusei IA‐1 fermentation broth was significantly improved when compared with that obtained using Saccharomyces cerevisiae broth. By treating the fermentation broth with activated carbon, bioethanol was concentrated as efficiently as with binary mixtures of ethanol/water. The total flux was improved upto 56% of that obtained from the separation of binary mixtures, compared with 43% before the addition of activated carbon. Nutrients such as peptone, yeast extract and corn steep liquor had a negative effect on pervaporation, but this response was distinct from that caused by succinate. CONCLUSION: For consistent separation of bioethanol from C. krusei IA‐1 fermentation broth by pervaporation, it is useful to treat the low nutrient broth with activated carbon. To further improve pervaporation performance, it will be necessary to suppress the accumulation of glycerol. Copyright © 2009 Society of Chemical Industry 相似文献
4.
JAPC (The Japan Atomic Power Company) is the only electric power company that operates different types of nuclear reactors in Japan; it operates two BWRs (boiling water reactors), one pressurised water reactor and one gas cooled reactor. JAPC has been conducting various activities aimed at reducing radiation dose received by workers for over 45 y. Recently, the collective dose resulting from periodic maintenance has increased at each plant because of the replacement of large equipment and the unexpected extension of the outage period. In particular, the collective dose at Tokai-2 is one of the highest among Japanese BWR plants((1)), owing to the replacement and strengthening of equipment to meet earthquake-proof requirements. In this study, the authors performed a multilateral analysis of unacceptably a large collective dose and devised a new ALARA programme that includes a 3D dose prediction map and the development of machines to assist workers. 相似文献
5.
Yasunori Oumi Hideo Yamano Momoji Kubo Rajappan Vetrivel Akira Miyamoto 《Catalysis Today》1995,23(4):417-423
The destruction processes of various zeolites, such as a silicalite with the ZSM-5 structure (SiO2-MFI), Cu-ZSM-5, and a silicalite with the faujasite structure (SiO2-FAU), with increasing temperature were investigated by using molecular dynamics and computer graphics methods. The mobility of atoms in SiO2-MFI was increased and the framework became unstable, as the temperature was increased. Finally the framework was destroyed to an amorphous phase. Increasing the Al content led to a decrease in the heat-resistance in Cu-ZSM-5. The change in the Si-O, Al-O, and Cu-Al distances as well as the change in the pairs of Si-O bonds are discussed to clarify the mechanism of Cu-ZSM-5 destruction. The destruction process of SiO2-FAU was also investigated in order to understand the effect of framework structure, and it was suggested that the presence of the 4-membered ring provides one of the reasons for the inferior heat-resistance of SiO2-FAU to that of SiO2-MFI. 相似文献
6.
H. Sasaki H. Jon M. Itakura T. Inoue T. Ikeda Y. Oumi T. Sano 《Journal of Porous Materials》2009,16(4):465-471
The hydrothermal conversion of FAU zeolite into aluminous MTN zeolite is described here. In the presence of both benzyltrimethylammonium
hydroxide (BTMAOH) and sodium chloride (NaCl) the highly crystalline and pure MTN zeolites with Si/Al ratios of 21-23 could
be obtained from the hydrothermal conversion of FAU zeolite. Based on powder XRD refinement and 13C CP/MAS NMR spectra, BTMA+ ions were not present in cages of the obtained zeolites, but TMA+ ions existed instead. It means that BTMAOH underwent degradation during the conversion. Moreover, the effects of Si/Al ratio
of starting FAU zeolite, synthesis parameters (BTMAOH/SiO2 and H2O/SiO2 ratios) and the addition of alkali metal chlorides on the hydrothermal conversion of FAU zeolite into MTN zeolite are discussed.
As compared to amorphous SiO2/γ-Al2O3, which produced impurity, the hydrothermal conversion of FAU zeolite showed a fast crystallization rate and a high selectivity
to MTN zeolite formation. These phenomena indicate that the assembly of locally ordered aluminosilicate species coming from
the decomposition or dissolution of FAU zeolite should be taking part in the conversion process. 相似文献
7.
Kosuke Yamaguchi Kei Inumaru Yasunori Oumi Tsuneji Sano Shoji Yamanaka 《Microporous and mesoporous materials》2009,117(1-2):350-355
Fundamental photocatalytic behaviors were investigated for mechanical mixtures of TiO2 crystalline particles (P25) and MFI type zeolite (silicalite) in the decomposition reaction of 2-propanol vapor in air for the first time. Mechanical mixing enables reliable comparisons to be made between photocatalysts because the contents of TiO2 and the adsorbent can be widely varied (51 times in this study) while keeping the particle size and crystallinity of TiO2 unchanged. That is, the use of mechanical mixture highlights the behavior of molecules adsorbed in the microporous crystals, keeping the TiO2 unchanged. In the case of the mixed photocatalysts, the initial 2-propanol concentration in the gas phase was significantly reduced because of adsorption into the zeolite. After photo-irradiation started, 2-propanol was decomposed to CO2 with no (or trace amount of) acetone detected in the gas phase. The analysis of final amount of CO2 formed by the decomposition demonstrated that just by the mechanical mixing of TiO2 and zeolite, the TiO2 photocatalyst decomposed completely the reactant and intermediate molecules strongly adsorbed into the zeolite. On the other hand, in reference experiments in which TiO2 and zeolite were not mixed and were separately placed in a photoreactor, the organic compounds strongly adsorbed in the zeolite could not be decomposed to CO2 by the photocatalyst. It is notable that the CO2 formation rates for the mixed photocatalysts were mostly constant for those comprising 40 wt% or larger amounts of zeolite, while being slower than for pure TiO2. The rate-determining step was discussed based on these data. The present study showed that the mixed photocatalyst could remove organic vapors by adsorption in the dark and decompose completely to CO2 at moderate reaction rates under photo-irradiation with minimized evolution of intermediate molecules into the gas phase. 相似文献
8.
Sadanobu?Sumiya Jun?Fujiwara Yasunori?Oumi Masahiro?Sadakane Tsuneji?SanoEmail author 《Journal of Porous Materials》2011,18(4):493-500
Incorporation of aluminum on the inner surfaces of mesopores was carried out under hydrothermal conditions for synthesizing
mesoporous silica using an anionic surfactant. The synthesis concept was based on ionic interactions between aluminum cations
and anionic surfactants, with the latter as templates. We easily obtained aluminum-containing microporous silica with supermicropores.
The results of pyridine adsorption and cumene cracking reactions strongly indicated that unlike the materials prepared by
the previously reported post synthesis and direct synthesis methods, the larger amount of aluminum incorporated into the materials
were effectively present on the inner surfaces of supermicropores. 相似文献
9.
Y. Oumi M. Yamadaya T. Kanougi M. Kubo A. Stirling R. Vetrivel E. Broclawik A. Miyamoto 《Catalysis Letters》1997,45(1-2):21-26
We report here the result of a computer- assisted study of metallosilicates by applying molecular dynamics (MD) and quantum
chemical (QC) methods. MD calculations are used to study the local relaxation in the T12 site of the ZSM-5 structure, when
Si is substituted by different metals such as Ti4+, Al3+, Ga3+, and Fe3+. QC calculations by density functional theory have been performed on the cluster models generated from the structure obtained
by MD calculations. The calculation indicates that the net charge on a MO4 (where M = Ti, Al, Ga, and Fe) group and the molecular electrostatic potential values are good parameters to assess the acidic
properties of metallosilicates, as shown by their correlations to the reported experimental acidity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Hitoshi Sasaki Yasunori Oumi Masahiro Sadakane Tsuneji Sano 《Journal of the European Ceramic Society》2010,30(6):1537-1541
Single phase Ca-α-SiAlON was synthesized for the first time by the carbothermal reduction-nitridation of a physical mixture of Y-type zeolite and CaO. Under well-optimized conditions, which included both a Si/Al ratio of 2.8 for the starting Y-type zeolite and a Ca/Al ratio of 0.63–0.75, highly crystalline, pure Ca-α-SiAlON was obtained. The formation of pure Ca-α-SiAlON was also confirmed by 27Al and 29Si MAS NMR measurements. 相似文献