島津 省吾

Mesoporous molecular sieves are promising as adsorbents for purification of biological molecules, such as arm no acids, due to their tuneable mesopore sizes and high surface area. In this study, the adsorption of the basic amino acid, lysine, onto MCM-41, a siliceous mesoporous molecular sieve, has been investigated Under a range of solution conditions. It was found to adsorb according to a Langmuir-type isotherm with a maximum capacity at pH 6 of 0.21 mmol/g. The extent of adsorption depends strongly on the pH and ionic strength of the adsorbate solution, due to a combination of ion exchange and electrostatic interactions governing the adsorption process. (c) 2005 Elsevier B.V. All rights reserved.

Two series of zirconium beta-diketonates: tris(benzoylacetonato)zirconium (IV) perchlorate (3b) and tris(dibenzoylmethanato)zirconium (IV) perchlorate (3c) were synthesized. The complexes were synthesized by a reaction of zirconium tetrachloride with corresponding ligands in a 1:3 molar ratio, followed by a reaction with silver perchlorate. Characterization was by elemental analyses, UV-Vis, FTIR and H-1 NMR spectroscopies. The complexes were prospective to serve as Lewis acid catalysts for ring opening reactions of oxiranes with alcohols for synthesizing primary alkoxyalcohols. Previously reported tris(acetylacetonato)zirconium (IV) chloride (2a) was used as comparison. The effect of phenyl ring on ligand frame towards enhancement of Lewis acidity of zirconium is focused. Other factors, such as nucleophile strength of alcohols and alkyl substituent of oxiranes are also discussed. (c) 2005 Elsevier B.V. All rights reserved.

Alumina supported gold catalyst prepared by spray reaction method (spr) provides gold particles with about 20nm diameter. The gold particle size is larger than for conventional gold catalysts. However, the spr catalyst shows catalytic activity for NO-CO reaction. In the present paper, we discuss the local structures of spr-Au/Al2O3 catalyst by using Au L3-edge XANES spectra. In order to investigate the local structures of Au-sites, multiple scattering approach to XANES analysis was applied. Calculated Au L3-edge XANES spectrum for fcc-Au and Au 2O3 were in good agreement with the observed spectra. XANES spectra for spr-Au/Al2O3 were characterized by 4 types of Au sites (bulk, interface, surface and peripheral). In this case, almost all gold sites (&gt 90%) are bulk sites. Less than 10% of the gold particles are in interface sites. However, the experimental result for spr-Au/Al2O3 requires about 30% of gold oxide or hydroxide. Bulk of Al2O3 contains a certain number of gold nano-particles, which was incorporated in the Al2O3 support. In the interface area, gold oxide forms a few layers. This result was also supported by DV-Xα electronic structure calculations. © Physica Scripta 2005.

Mesoporous silica supported Nb catalyst (imp Nb/SBA-3) was prepared by impregnation of NbCl5 to the SBA-3 support. The mesoporous silicate-wall incorporated Nb catalyst (inc Nb-SBA-3) was synthesized by introducing NbCl5 into an SBA-3 precursor solution. Both catalysts were carburized by a temperature programmed reaction (TPR) method under CH 4/H2 gas stream. Nb K-edge in-situ XAFS analysis revealed that Nb2O5 was reduced to NbO2 in the first stage of TPR and converted into NbC in the second stage. The silica-wall incorporated Nb species were highly dispersed and hardly reduced nor fully carburized. The difference in the carburization process between imp Nb/SBA-3 and inc Nb-SBA-3 was clarified. © Physica Scripta 2005.

Silica supported molybdenum oxide catalysts were prepared from Mo dimer complex (Mo2(CH3CO2)4) by using photochemical anchoring (PCA) method. The local environments of Mo atoms on both attached and oxidized catalysts were investigated by Mo K-edge EXAFS, XANES, Raman spectroscopy and thermal gravimetric analysis. The bond distance between dimeric Mo atoms could be changed depending on the energy of UV irradiation. By using the lower irradiation energy (λ &gt 350 nm), the attached structure was close to the original Mo dimer complex. After oxidation of the catalyst, dimeric structure was formed with bridging oxygen and the Mo-(O)-Mo bond distance was 0.316 nm. On the other hand, in the case of higher irradiation energy (λ &gt 250 nm), the Raman spectrum of the attached catalyst had bands due to acetate ligands except a band at 405 cm-1 due to Mo-Mo skeleton bond. It means that Mo2(CH3CO2) 4 is decomposed by UV irradiation. The oxidized form of the higher energy irradiated catalyst showed monomer-pair structure. © Physica Scripta 2005.

2-Methoxy-1-propanol has been selectively synthesized using clay supported tris(2,4-pentanedionato)zirconium(IV), prepared by facile ion-exchange process. The tris(2,4-pentanedionato)zirconium(IV) cation was synthesized by refluxing zirconium chloride with acetylacetone in chloroform. The heterogenized complex showed an increase in conversion rate and selectivity compared to the homogeneous one. Selectivity of 58% towards primary methoxypropanol was achieved under mild reaction condition. The clays selected as supporting materials were synthetic taeniolite and natural bentonite. It was observed that natural bentonite showed similar activity to synthetic taeniolite as a catalyst support. (C) 2004 Elsevier B.V. All rights reserved.

Novel nano-structured clays were synthesized from cation exchange reaction by the intercalation of rhodium complexes with ligand spacers into clay. Expansion of interlayer space of the modified clays depends on the spacers. A unique conformation of pillar complexes was detected by cross polarization magic angle spinning (CP MAS) NMR.

Gold catalysts supported on titanium dioxide were prepared by the suspension spray reaction (SSP) method that was developed as a modification of the previous solution spray reaction (SPR) method. The effects of suspension spray reaction temperature on the surface structure and the characteristic properties were investigated by means of XRD, TEM, XPS and CO chemisorption measurements. The particle sizes of gold prepared at higher spray temperatures turned out to be smaller and the surface distribution of gold increased. These effects are interpreted in terms of the strong interaction between gold and TiO2 which prevents the coagulation and crystal growth of gold nanoparticles during the spray reaction. The deconvolution of XPS spectra for as-sprayed SSP-Au/TiO2 Suggests that An species existed in three different states: i.e. metallic gold (Au-0), non-metallic gold (Audelta+), and Au2O3 species. Further, the metallic Au-0 was exposed more. effectively over the surface of the catalysts prepared by higher temperature spraying. The amount of CO chemisorption over SSP-Au/TiO2 1073 prepared at 1073 K was about five times larger than that over SSP-Au/Ti02673; this difference is consistent with the above result for XPS. The catalytic activity for CO oxidation expressed by the initial rate and TOF increased with the spray reaction temperature. The high catalytic activity of SSP-Au/TiO2 1073 is attributed to the highly dispersed gold particles being modified by a strong interaction with TiO2 that induced a synergy effect in the catalysis. (C) 2003 Elsevier Science B.V. All rights reserved.

Mo catalysts anchored on MCM-41 and incorporated into SBA-3 framework were prepared. XRD and TEM analysis revealed that both catalysts maintained their mesoporous structure. However, Mo/MCM-41 catalyst prepared by conventional impregnation lost the ordered mesoporous structure. Structural differences were analyzed by in-situ XAFS measurement under propene photometathesis condition. Structure and the catalysis were also discussed based on the differences between irradiated and unirradiated structures.

SiO2-supported NbC catalysts were prepared by using temperature-programmed reactions (TPR). XAFS analysis confirmed that Nb2O5 was reduced to NbO2 in the first TPR stage and converted into NbC in the second TPR stage. Nb particles grew only in the second TPR stage. Formation of highly dispersed NbC particles on SiO2 surfaces was achieved.

Spray reaction (spr) method was applied to prepare Co/Al2O3 catalysts and Ni/Al2O3 catalysts and clarified synergetic effects between metal and mixed-oxide, and between metal oxide and mixed-oxide playing important roles for catalysis; NO-CO reaction on spr Co/Al2O3 and CO hydrogenation on spr Ni/Al2O3. The various applicability of the catalyst design by using spr was discussed.

Doped TiO2 photocatalysts were prepared by spray reaction method. The photocatalytic isomerization of cis-2-butene to 1-butene at 323 K has been employed to study a photocatalytic properties. The applicability of spray reaction method to the preparation of TiO2 and doped-TiO2 photocatalysts were proposed.

Fe³⁺, Al³⁺, Zr⁴⁺カチオンで交換したリチウムテニオライトが, アルコールの脱水反応において固体酸触媒として触媒活性があり, なかでもFe³⁺カチオンで交換したFe交換テニオライトが最も高活性であることを見いだした。この触媒活性が反応温度と前処理温度に依存することは層間隔の温度依存性から説明することができ, 反応は層間で進行していることが示唆された。いずれの固体酸触媒についても, アルコールの分子間脱水と分子内脱水に対する特異的な形状選択性は認められなかった。ホスト化合物をモンモリロナイト, リチウムヘクトライトとした場合には, アルコールの脱水活性は非常に低くなった。ホスト化合物の違いによる反応活性の相違は, ホスト化合物層間のFeの存在状態がテニオライトと異なること, 即ちFe交換テニオライト中のα-ゲーサイトが活性点であると考えることにより説明できた。ピリジン-TPD法から求められる酸量と触媒活性との間によい相関関係が認あられ, ピリジン-TPD法がカチオン交換した層状化合物の酸量の評価法として優れていることがわかった。

Fe³⁺, Al³⁺, Zr⁴⁺カチオンで交換したリチウムテニオライトが, アルコールの脱水反応において固体酸触媒として触媒活性があり, なかでもFe³⁺カチオンで交換したFe交換テニオライトが最も高活性であることを見いだした。この触媒活性が反応温度と前処理温度に依存することは層間隔の温度依存性から説明することができ, 反応は層間で進行していることが示唆された。いずれの固体酸触媒についても, アルコールの分子間脱水と分子内脱水に対する特異的な形状選択性は認められなかった。ホスト化合物をモンモリロナイト, リチウムヘクトライトとした場合には, アルコールの脱水活性は非常に低くなった。ホスト化合物の違いによる反応活性の相違は, ホスト化合物層間のFeの存在状態がテニオライトと異なること, 即ちFe交換テニオライト中のα-ゲーサイトが活性点であると考えることにより説明できた。ピリジン-TPD法から求められる酸量と触媒活性との間によい相関関係が認あられ, ピリジン-TPD法がカチオン交換した層状化合物の酸量の評価法として優れていることがわかった。

粘土層間担持パラジウム (II) 錯体を合成し, IR, XRD, XPSにより構造分析を行った。ホスト化合物としてリチウムヘクトライト (LHT) , ゲスト化合物として [Pd (NH₃) ₄] ²⁺と [Pd (PDT) ₃] ²⁺を用いた。 [PD (NH₃) ₄] ²⁺/LHT (PdAm/LHT) と [Pd (PDT) ₃] ²⁺/LHT (PdPDT/LHT) の底面間隔 (d₀₀₁) はそれぞれ1.30nmと2.21nmに変化した。これらの錯体担持ヘクトライトをDMSO溶媒に膨潤させると底面間隔はさらに拡大し, PdAm/LHTとPdPDT/LHTはそれぞれ, 1.45と2.94nmに拡大したが層構造を保持していた。これらの層間担持錯体を用いて種々の形状を持つアルキンの水素化反応を行った。層間担持触媒の活性は, その層間隔と基質の分子サイズに大きく依存した。小さい層間隔を持つPdAm/LHTでは, 分子サイズの大きいフェニル, t-ブチルアセチレンの水素化にほとんど活性を示さなかった。しかし, 大きい層間隔を持つPdPDT/LHTではフェニルアセチレンを容易に水素化したが, t-ブチルアセチレンに対しては低活性であった。さらに, これら層間担持触媒は, アルキンからアルケンへの高い部分水素化選択性を示した。

ビニルシランの励起状態の電子構造とプラズマ反応性の相関について検討した。MNDO分子軌道法による二中心結合エネルギーと局在化分子軌道エネルギーの計算結果から,最低励起状態では,オレフィン結合のπ部分が開裂し,第二励起状態では,Si-C結合が伸びて弱くなることが示唆された。特に三重項励起状態において,その傾向が強い。最低励起三重項状態への励起エネルギーは,他の励起状態よりかなり低く,ビニルシランの化学反応を誘起する励起エネルギーを低エネルギー側に絞れば,この励起状態を経由する反応がかなり選択的に起こることが予測される。高周波プラズマによるグロー放電分解の実験結果は,この計算による予測によく対応した。生成薄膜のXPSおよびIRスペクトルから,低パワーにおいてはオレフィン結合のπ部分の開裂により炭素骨格が形成され,パワーを上げていくとSi-C結合の切断が起こり,C/Si比を連続的に変化させてa-Sic膜を形成することができた。

Aminated lithium hectorites, HT-A1 (-OSiMe2CH2OCH2CH2NH2) and HT-A2 (-OCH2CH2NH2), were prepared by chemical modification of the OH group in lithium hectorite (LHT). Interlayer-supported PdIIcomplexes on LHT, Pd/HT-A1 and Pd/HT-A2 were synthesized by the reaction of [Pd(OAc)2]3with HT-Al and HT-A2, respectively. XRD studies showed that the basal spacings (d001) of LHT and Pd/HT-A1 swollen with solvents varied with the dipole moment of the solvent. Catalytic activities and selectivities of Pd/HT-A1 for the hydrogenation of mono-olefins and dienes were investigated in the liquid-solid heterogeneous system. The hydrogenation rate decreased in the order 1-pentene > 2-methyl-1-butene > cyclo-octene. The selectivity for partial hydrogenation depended on the type of diene: conjugated dienes > unconjugated dienes. The selectivity for the partial hydrogenation of isoprene by Pd/HT-A1 was independent of the solvent, while that of the homogeneous catalyst [Pd(OAc)2]3increased with increasing dipole moment of the solvent. © 1989.

Hectorite(LHT)-intercalated Pd[II] complex catalysts, [Pd(NH3)4]2+/LHT and [Pd(PDT)3]2+/LHT, were prepared and characterized by XRD and IR measurements. The basal spacings(d001) of [Pd(NH3)4]2+/LHT and [Pd(PDT)3]2+/LHT were 1.30 nm and 2.21 nm in air, respectively. When the intercalated catalysts were swelled with the DMSO solvent, d001 became 1.45 nm for [Pd(NH3)4]2+/LHT and 2.94 nm for [Pd(PDT)3]2+/LHT. These two types of the intercalated Pd[II] complex catalysts were used for hydrogenation of alkynes in DMSO to study the effect of the clearance spacings(= d001 - 0.96 (nm) for LHT) on their catalytic activities. © 1989.

Catalytic properties of metal cations on sulfonic resin have been studied in ester hydrolysis. The catalytic activities were related to the electronegativity of the metal cation, while the activation energies were close to that for H-form resin and not affected by the cation concentration, suggesting the variation of entropy factors in catalysis. © 1988 Akadémiai Kiadó.

In relation to photoconduction, the photo-oxidation of Te films was investigated as a function of photon irradiation energy by both photo-stimulated current and XPS measurements. Two modes of photo-oxidation were observed. These modes may be explained as follows. (1) The absorption edge of TeO2 is 4.1 eV and optical absorption increases rapidly at this energy. The photon energy absorbed is exhausted to oxidize the Te film. (2) The other mode is connected with the formation of ozone which occurs above 4.9 eV and rapid oxidation arises with activated oxygen. By XPS measurement, the UV photo-oxidation process was also investigated as a function of irradiation time. The oxygen of minus one valence was found to increase in the oxidation process by UV light, which may play an important role in the oxidation process. Moreover, photolysis is verified to be a cause of photoconduction on photo-oxidized Te film by investigating the UV illumination effect on the XPS spectrum. © 1988.