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Surface-modified mesoporous silicas (MSs) were investigated for recyclable adsorption of an endocrine disrupter, bisphenol A (BPA). Surface-modified MSs were prepared by (i) post-synthesis surface modification of MSs using surface hydroxyl groups and organosilanes (m-MS) and by (ii) co-condensation of tetraethoxysilane and the corresponding organosilanes (d-MS). Infrared measurements indicated that organic groups mainly existed on the surface of m-MS, which resulted in a surface characterized by high hydrophobicity. Both organic groups and isolated hydroxyl groups existed on the surface of d-MS, resulting in both hydrophobicity and hydrophilicity on the surface. The amount of BPA adsorbed on surface-modified MSs per organic group was similar for m-MS and d-MS, however, the d-MS established equilibrium for BPA adsorption faster than m-MS, as measured by UV-vis spectra. A larger amount of BPA per surface area could be adsorbed on carbon materials than on the surface-modified MSs, however, the regeneration of carbon materials by washing could not be done easily. The surface-modified MSs retain adsorption capacity for BPA after several regeneration cycles, demonstrating that the surface-modified MSs are effective recyclable adsorbents of the endocrine disrupter, bisphenol A. 相似文献
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Aritomo Yamaguchi Norihito Hiyoshi Osamu Sato Mitsumasa Osada Masayuki Shirai 《Catalysis Letters》2008,122(1-2):188-195
Lignin gasification in supercritical water over charcoal supported ruthenium trivalent salts was studied using a batch reactor
at 673 K. Ruthenium (III) nitrosyl nitrate on charcoal (Ru(NO)(NO3)3/C) was more active than ruthenium (III) chloride on charcoal (RuCl3/C) for the gasification reaction. EXAFS analysis revealed that ruthenium metal particles were formed in both RuCl3/C and Ru(NO)(NO3)3/C catalysts during the lignin gasification and that the size of ruthenium metal in Ru(NO)(NO3)3/C was smaller than that in RuCl3/C. It was concluded that well-dispersed ruthenium metal particles were active for the lignin gasification in supercritical
water. 相似文献
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Aritomo Yamaguchi Takafumi Shido Yasuhiro Inada Toshihiro Kogure Kiyotaka Asakura Masaharu Nomura Yasuhiro Iwasawa 《Catalysis Letters》2000,68(3-4):139-145
The time-resolved reduction process of copper cations in/on ZSM-5 during temperature-programmed reduction (300–700 K) was studied by energy-dispersive X-ray absorption fine structure (DXAFS) as well as transmission electron microscopy (TEM). Two Cu-ZSM-5 samples with different Cu loadings were prepared by an ion-exchange method. The Cu K-edge DXAFS spectra for isolated Cu2+ species in the channels of ZSM-5 and CuO particles on the outer surfaces of ZSM-5 were recorded at an interval of 1 s during the reduction. The curve fitting analysis of the EXAFS data and the XANES analysis revealed that the isolated Cu2+ species in the channels were reduced stepwise. They were reduced to isolated Cu+ species at 400–450 K and the Cu+ species to Cu0 metallic clusters at 550–650 K. Small clusters like Cu4 were initially formed, followed by particle growth. A small part of them went out to the outer surfaces of ZSM-5 during the reduction. In contrast, CuO particles on the outer surfaces were reduced directly to Cu0 metallic particles around 450 K. 相似文献
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Shido Takafumi Yamaguchi Aritomo Inada Yasuhiro Asakura Kiyotaka Nomura Masaharu Iwasawa Yasuhiro 《Topics in Catalysis》2002,18(1-2):53-58
A time-resolved energy dispersive XAFS (DXAFS) technique is applied to elucidate the local structure of catalyst precursors and active species during the preparation of catalysts. The structure of ion-exchanged copper species in ZSM-5 zeolite during temperature-programmed reduction and the structure of molybdenum carbonyl species in NaY zeolite during temperature-programmed decarbonylation were investigated by the DXAFS technique. The way of the analysis of XAFS data during the dynamic processes is also discussed. The XANES spectra were analyzed to determine the ratio of different species involved in the system as a function of temperature as well as the curve-fitting analysis of the time-resolved EXAFS. The detailed analysis of the XANES and EXAFS shed light on the structural changes during the dynamic processes. In Cu-ZSM-5, a stepwise reduction process of Cu species and the subsequent growth of Cu particles during the reduction were elucidated. In Mo–NaY, the formation of Mo subcarbonyl monomer species as an intermediate of molybdenum oxycarbide dimer species was observed. This paper demonstrates that the DXAFS technique is useful to study the chemistry of catalyst preparation and can provide vital information that cannot be obtained by other techniques. 相似文献
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Aritomo Yamaguchi Norihito Hiyoshi Osamu Sato Masayuki Shirai 《Topics in Catalysis》2012,55(11-13):889-896
Charcoal supported metal salt catalysts showed activities for the lignin gasification at 673 K, especially the catalysts without chloride anion showed the complete gasification. The order of activity for the gasification among the metal species was following: ruthenium > rhodium > platinum > palladium ~ nickel. X-ray absorption fine structure analysis revealed that small metal particles were formed on the charcoal support after the gasification for the supported ruthenium, rhodium, and platinum salt catalysts without chloride anion; on the other hand, larger metal particles were formed in the presence of chloride anion. Lower activities and deactivation for supported metal salt catalysts having the chloride anion were caused by poisoning by chloride anions and the smaller number of metal sites. 相似文献
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Aritomo Yamaguchi Akane Suzuki Takafumi Shido Yasuhiro Inada Kiyotaka Asakura Masaharu Nomura Yasuhiro Iwasawa 《Catalysis Letters》2001,71(3-4):203-208
The temperature-programmed decarbonylation process of Mo(CO)6 in NaY zeolite was studied by means of a time-resolved energy-dispersive XAFS method. The XANES analysis demonstrated that the decarbonylation proceeded by two successive steps via a stable intermediate which existed between 440 and 490 K. The curve fitting analysis of the EXAFS data revealed that the intermediate was a molybdenum monomer subcarbonyl species Mo(CO)3(OL)3 coordinated by three CO ligands and three oxygen atoms of zeolite framework (OL). Molybdenum dimer subcarbonyl species were not observed. This study demonstrated that the DXAFS technique is a powerful method to study the dynamic behavior of the Mo carbonyl species during decarbonylation process. 相似文献
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Tsutomu Chida Kousuke Hiromori Naomi Shibasaki-Kitakawa Naoki Mimura Aritomo Yamaguchi Atsushi Takahashi 《Journal of the American Oil Chemists' Society》2020,97(12):1365-1370
Glycerol can be effectively converted to glyceric acid, a high value-added pharmaceutical raw material, through its partial oxidation over an Au/Al2O3 catalyst under strongly basic conditions. The factors important for the highly selective production of glyceric acid were investigated experimentally. It was clarified that NaOH was involved in the glycerol activation step to a glycerol alkoxide intermediate (2, 3-dihydroxypropoxide) in the liquid phase, then glyceric acid was formed by OOH species derived from O2 on an Au catalyst in the partial oxidation step. We have newly discovered the concerted effect of NaOH and O2 in different reaction steps. 相似文献
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Aritomo Yamaguchi Norihito Hiyoshi Osamu Sato Masayuki Shirai 《Topics in Catalysis》2010,53(7-10):487-491
High-temperature liquid water treatment of triol compounds [1,2,3-propanetriol (glycerol), 1,2,4-butanetriol (1,2,4-BTO), and 1,2,5-pentanetriol (1,2,5-PTO)] was carried out using a batch reactor. Intramolecular dehydration to hydroxyacetone from glycerol, 3-hydroxytetrahydrofuran from 1,2,4-BTO, and both tetrahydrofurfuryl alcohol and 3-hydroxytetrahydropyran from 1,2,5-PTO proceeded in water at 573 K. The dehydration rates were enhanced by the addition of high-pressure carbon dioxide. 相似文献
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