島津 省吾

An active Pd(II) catalyst supported on the Ni-Zn mixed basic salt (NiZn), which is classified by the anion-exchangeable layered hydroxy double salts, was synthesized by simple intercalation of the anionic Pd(II) hydroxyl complex. The divalent Pd species in the interlayer of NiZn maintained their original monomeric structure during the aerobic alcohol oxidation, due to the strong electrostatic interaction between the NiZn host and anionic Pd(II) species. This catalyst could be reused without any loss of the catalytic activity and selectivity in the aerobic alcohol oxidation.

The performance of catalysts from the platinum group and Cu-based catalysts were compared in the dimethyl ether (DME) steam reforming reaction. Without acidic oxides, Cu-based catalysts formed undesired CH4 via a direct decomposition of DME into methoxy (-OCH3) and methyl (-CH3) groups, followed by the hydrogenation of the methyl group to CH4. However, in the presence of acidic oxides such as Al2O3, practically no CH4 was produced. Therefore we speculate that the MeOH formed on the acidic sites moves onto Cu and is adsorbed as a methoxy group without the co-formation of a methyl group, preventing the formation of CH4 and leading to an even higher yield of H-2. Pt/Al2O3 and Ru/Al2O3 showed a relatively high DME conversion, although the undesired production of CH4 was quite high, irrespective of the presence of acidic sites. A high CH4 selectivity can be explained in terms of a high methanation activity. The catalyst formed from CuMn2O4 spinel oxide mixed with Al2O3 showed higher activity and greater durability than commercial CuZnAl catalysts mixed with Al2O3. By replacing Al2O3 with H-ZSM5, the CuMn2O4 spinel oxide showed a further increase in activity resulting in up to 100% conversion even under 300 degrees C. We attribute this very high activity at relatively low temperature to both the high DME hydration activity of H-ZSM5 and the high MeOH steam reforming activity of CuMn2O4 spinel oxide. (C) 2008 Published by Elsevier B.V.

Nb/Al2O3 and Nb/SiO2 as niobium carbide precursors were prepared from peroxoniobic acid (PNA). Alumina-supported niobium carbide and silica-supported niobium carbide were prepared by temperature programmed reaction (TPR) method under CH4-H-2 mixed gas passage. Both catalysts were characterized by X-ray absorption fine structure (XAFS) and Raman spectroscopy. Nb/Al2O3 was more efficiently carburized than Nb/SiO2. The carbon deposition onto NbC occurred after the carburization completion of the Nb species. (C) 2008 Elsevier B.V. All rights reserved.

Two series of palladium(II)-alkylamine (Pd(Me(2)NCn)(2)(OAc)(2), Me(2)NCn: N,N'-dimethylalkylamine, n = 4, 8, 12, and 16) and palladium(II) N,N'-dialkylamine (Pd(Cn(2)NH)(2)(OAc)(2), Cn(2)NH: N,N'-dialkylamine, n=4,8, and 12) were prepared. These homogeneous Pd complexes catalyzed the aerobic oxidation of wide range of alcohols into the corresponding aldehydes and ketones efficiently. For example, a benzylalcohol oxidation proceeded rapidly by means of Pd(Me(2)NCl2)(2)(OAc)(2) with an excellent turnover frequency of up to 96 h(-1). (C) 2007 Elsevier B.V. All rights reserved.

Lowering the carburization temperature of Ti-oxide into TiC down to 1173 K could be achieved by the addition of Co. Co-promoted TiC/Si-2 catalysts were prepared by the temperature programmed reaction (TPR) method. Co-Ti/SiO2 precursors were prepared by use of the successive impregnation method (sc) and the co-impregnation method (co). Samples were characterized by X-ray absorption fine structure (XAFS) measurements and X-ray diffraction (XRD) results. The carburization degree of TiC was affected by the method of Co addition. The carburization degree of sc Co-TiC/SiO2 was better than that of co Co-TiC/SiO2. The activity of thiophene hydrodesulfurization reaction at 693 K on sc Co-TiC/ SiO2 was higher than that on co Co-TiC/SiO2. The HDS activity was related to the carburization degree of TiC. (C) 2007 Elsevier B.V. All rights reserved.

粘土鉱物などのイオン交換性層状化合物の層空間に金属錯体を活性種として導入してナノ構造体触媒を合成し, 様々な分子認識触媒の開発を行った。膨潤性の層状化合物は, 金属錯体 (活性種) や反応場の修飾剤 (チューニングゲスト) を導入するホストとして好適な材料である。特にスメクタイト系粘土鉱物は, 膨潤性に優れ極性溶媒により大きく層間を広げることから, 巨大な金属錯体を中性あるいはイオンの状態で容易に層間に導入できる。さらに, 層間に導入したゲスト錯体の立体配座が制御可能であることを見いだし, ナノレベルでの層間反応場の構築を試みた。ここでは, 金属錯体と構造チューニングゲストとの組み合わせる方法と, 構造チューニング機能を備えたピラー錯体を用いる方法で合成したナノ構造体触媒について紹介する。

Fe-Nb/SiO2 catalyst was prepared from NbCl5 or peroxoniobic acid as Nb precursors. These precursor catalysts were nitrided by the TPR method under N-2-H-2 passage (without using NH3). Nb K-edge in-situ XAFS measurements were carried out during the nitriding process and revealed that the Nb species was more nitrided in the FeNb/SiO2 catalyst prepared from peroxoniobic acid than in that prepared from NbCl5 as Nb precursor.

An Mo/MCM-41 catalyst was prepared and used for study of propene and 1-butene photo-metathesis reactions. XAFS analysis revealed that hydrogen reduction leads to a decreased role for the Mo=O site. The Mo-O site plays an important role for the olefin photo-metathesis reaction on the H-2 reduced Mo/MCM-41. From EXAFS analysis, the active site of photo-metathesis reaction is the Mo=O part for oxidized Mo/MCM-41, whereas it is the Mo-O site for reduced Mo/MCM-41.

Photometathesis of C3H6 proceeded on the sprayed MoO3 catalyst under UV irradiation with wavelength <290 nm. The photoactivity on the spray catalyst was 20-fold higher than that on the commercial MoO3. The X-ray diffraction (XRD) results showed the anisotropic growth of the crystal in the spray catalyst. The edge-rich structure was formed in the bulk molybdenum oxide by spray reaction technique.

A palladium(II)-aminosilane complex supported on MCM-41 (Pd-AEAPSi/MCM (1)) was prepared by the complexation of palladium(II) acetate to 3-(2-aminoethyl)aminopropyl (AEAPSi) groups grafted on MCM-41. FT-IR and C-13 CP MAS NMR studies indicated that AEAPSi chelated to palladium(II) to form the Pd(II)-AEAPSi complex. Regioselective hydrogenation of dienes was carried out by the obtained 1 as a catalyst. Pd-AEAPSi/MCM exhibited remarkably high reaction rates for the dienes with a hydroxyl group such as geraniol and linalool, while for limonene without OH group the reaction rate, was notably low. The MCM-supported catalyst also showed noticeably high regioselectivity in the hydrogenation of dienes with OH group. These results indicate that the hydrophilic interaction between the MCM-41 surface and the substrates plays an important role in the rate-determining step. (C) 2002 Elsevier Science B.V. All rights reserved.

Clay-supported metal complexes were prepared by various methods such as cation exchange, chemically anchored ligand, and interlayer-polymerized ligand methods. Multiple modification of smectites with metal complexes and various organic guests(tuning guests)can be applied to the preparation of catalysts for the molecular recognition reactions such as shape selective, chemoselective, regioselective, and asymmetric hydrogenations. Especially, chiral Rh-phosphine complexes intercalated in taeniorite with structural tuning guests exhibited notably high activity and high selectivity in the asymmetric hydrogenation of acetophenone due to the larger open space in their interlayer structure.

Clay-supported metal complexes were prepared by various methods such as cation exchange, chemically anchored ligand, and interlayer-polymerized ligand methods. Multiple modification of smectites with metal complexes and various organic guests (tuning guests) can be applied to the preparation of catalysts for the molecular recognition reactions such as shape selective, chemoselective, regioselective, and asymmetric hydrogenations. Especially, chiral Rh-phosphine complexes intercalated in taeniorite with structural tuning guests exhibited notably high activity and high selectivity in the asymmetric hydrogenation of acetophenone due to the larger open space in their interlayer structure.

Nb2O5/SiO2was carburized by TPR process in a stream of 20% CH4/H2gas mixture to produce NbC/SiO2. The XAFS analysis confirmed that Nb2O5was reduced to NbO2at the first stage, and converted into NbC at the second stage. The growth of Nb particle was not observed in the former process, but in the latter process. Although the NbC particle size of 4wt% catalyst (3.15 nm) was larger than those for the conventional 2wt% catalyst (2.29 nm), the successive carburized catalyst (4wt%MC) had a similar size (2.51 nm) to the 2wt%. The design of highly dispersed NbC particle on SiO2surface was achieved by the MC method. The effect of carbon on the structure has also been investigated.

Molybdenum oxide catalysts prepared by the spray reaction method had anisotropy in their crystal structures. In the present paper, the surface structure and the photoactivity for propen metathesis of the spray catalyst compared with the commercial MoO3 were investigated. In the XPS, the main peak of the spray catalysts was similar to that of the commercial MoO3 with the other characteristic peaks of Mo 3d(3/2) and 3d(5/2). The activity of spray catalysts showed higher than that of the commercial MoO3, and increased with increasing the Tspr, suggesting the formation of the characteristic active species due to the preparation method, i.e. rapid heating and quenching steps, for the spray reaction method.

In order to clarify the unique catalysis of gold nanoparticles, supported gold catalysts, i.e., different Au/TiO2samples in the form of fine composite, prepared by spray reaction method (SPR) were investigated. The structure of spr-Au/TiO2catalysts was studied by SEM, TEM and XRD. The effects of preparation conditions for the spray reaction, such as the solution concentration and the calcination temperature, on the surface characteristics are discussed. The catalytic behavior of spr-Au/TiO2catalysts for CO oxidation was studied. The spr-Au/TiO2catalysts calcined at high temperature, i.e., spr0.1/1073 and spr0.2/1073, gave the relative high turnover frequency (TOF) irrespective of the limited active sites. The high catalytic activity of spr0.1/1073 and spr0.2/1073 was attributed to the extensive perimeter interface between Au and TiO2support particles, which enhanced a synergistic effect.

Ru/Al2O3 catalysts were prepared by a suspended spray reaction (SSP) method applying a high temperature at 1273 K. The particles of SSP-Ru/Al2O3 were spherical sub-micron composites. The ruthenium species were not sintered but highly dispersed with small crystallite size (&lt 2 nm) over Al2O3 that retained the original surface area.

Taking the advantage of excellent applicability for multi-component fine particles, new types of supported metal catalysts, Ru/Al2O3and Ru/TiO2were prepared by a spray reaction method. The structure and characteristics were studied by SEM, TEM, XRD and EXAFS. The high performance catalytic behaviors were clarified in the hydrogenation of CO2and the hydrocracking of ethane comparing with those by an impregnation and a hybrid method.

Ni/Al2O3 catalysts were prepared by the spray reaction method. The NiO particles supported on NiAl2O4 were stabilized against the aggregation and converted into smaller Ni particles by H-2 reduction. The Ni particles stabilized on NiAl2O4 marked anomalous high activity for CO hydrogenation, due to the stronger interaction between Ni and NiAl2O4.

Ru/TiO2 catalysts were prepared by spray reaction (SFR) and conventional impregnation (IMP) methods. The catalytic activities of SPR fine particles were much higher than those of LMP catalysts for CO2 hydrogenation. A high temperature reduction greatly promoted the activity of SPR catalyst. A model of surface structure was proposed which exhibits the enhancement of decoration and the formation of more boundaries over spr-Ru/TiO2. The high activity of SPR catalyst is attributed to the occurrence of new active sites at the metal-support perimeters and not any SMSI phenomenon. EXAFS reveals that the Ru atom was interacting with TiO2 by oxygen atom so strongly on the SPR catalysts that a part of the Ru atoms, located near the internal interface between Ru particles and TiO2 support, existed as Run+ (n<4) cations even if SPR catalyst was subjected to a high temperature reduction. These Run+ cations are responsible for the inhibition of SMSI formation over SPR catalysts. (C) 1999 Elsevier Science B.V. All rights reserved.

Rhodium complex with a chiral phosphine ligand was intercalated into sodium hectorite by cation exchange method. The intercalation compound was characterized by FT-IR, XRD and TEM measurements. The basal spacing of the compound was estimated to be 2.29 rim from XRD measurement. This novel heterogenized catalyst exhibited a characteristic chiral as well as size recognition of the substrates in the hydrogenation of itaconates. (C) 1999 Elsevier Science B.V. All rights reserved.

Three series of Ru/Al2O3 catalysts were prepared by spray reaction (SPR), impregnation (IMP), and these two methods combined. The characteristics of multi-component SPR particles, as CO2 hydrogenation catalysts, were elucidated. The catalytic activity (TOF) of SPR fine particles was higher by one order of magnitude than that of IMP catalyst without any promoters. This is attributed to the formation of more active species at the perimeters between Ru metal and Al2O3 over SPR particles than over IMP catalysts. The addition of alkaline salts promoted the catalytic activity of Ru/Al2O3, irrespective of preparation methods employed. The promotion of alkali metals to Ru/Al2O3 catalysts is probably due to a synergetic effects including the modification of local electron density on Ru metal by the electron donation of alkali metals, the neutralization of residual chlorine ions by the formation of alkaline chloride, and the removal of depositional inactive carbon by alkaline carbonate catalysis. (C) 1998 Elsevier Science B.V. All rights reserved.

The novel host-guest catalysts, in which a chiral rhodium complex was intercalated into structural tuning guests modified smectites, were synthesized, and drastic change in catalysis was observed depending on the orientation of guest molecules.

粘土鉱物やリン酸ジルコニウムなどのイオン交換性層状化合物の層空間を修飾しさらに金属錯体を活性種として導入して, 多様な分子認識触媒の開発を試みた。膨潤性層状化合物は, 金属錯体 (活性種) や反応場の修飾剤 (チューニングゲスト) を導入するホストとして好適な材料である。特にスメクタイト系粘土鉱物は, 膨潤性に優れ極性溶媒により大きく層間を広げることから, 巨大な金属錯体あるいはイオンを種々の方法により容易に層間に導入できる。ここでは, イオン交換法, あらかじめ層間に配位子を導入した層間化学固定化法, 層間重合法について説明し, 金属錯体を固定化した粘土鉱物の構造および分子認識性について述べる。さらに, これら層間固定化錯体を用いて, 分子サイズ選択性, 官能基選択性, 位置選択性, 不斉選択性などの分子認識触媒作用を調べた。特に, Rh-キラルホスフィン錯体を固定化した層間化合物は, 均一系錯体に見られない特有な基質の分子サイズおよび不斉の両選択性を合わせ持つ多重認識性を示した。

Hectorite(HT)-supported Rh complex catalysts were prepared by the intercalation of [Rh(P*-P*)(COD)]+(P*-P* = (S)-BINAP and (S)-(R)-BPPFA, COD = cyclooctadiene) into sodium hectorites (NaHT) in acetonitrile/H2O. The basal spacing of each modified clay was 2.94 nm (BINAP) and 2.72 nm (BPPFA), respectively. Asymmetric hydrogenation of α,β-unsaturated carboxylic acid esters containing ester groups of various chain lengths was studied on these modified hectorites. The dependence of selectivity on employed solvents and bulkiness of the ester groups suggested that the interaction between substrates and the active sites increased in the interlayer space, thus enhancing the asymmetric selectivity.

Fe<SUP>3+</SUP>, Al<SUP>3+</SUP>, Zr<SUP>4+</SUP>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Fe<SUP>3+</SUP>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。

合成粘土の層空間を修飾し金属錯体を活性種として導入して, 分子認識触媒機能を設計するための要素的方法の開発を行った我々の試みを中心にまとめた。膨潤性粘土の層状構造は金属錯体を導入して固定するのに好適な材料であり, 化学固定, イオン交換, 分子間力などによって活性種の層間への導入が可能である。さらに, 層間の反応場の修飾は"チューニングゲスト"の導入によっても可能であり, 層空間の幾何学的大きさ, 疎水/親水性や不斉反応場などの制御によって, 分子認識的触媒反応場が形成される。<br>ここでは層間の反応場を利用する分子認識の要素的機能を個別に検討した結果, 層間錯体による脂肪族アルキンや脂肪族アルデヒドの鎖長選択水素化, 共役ジエン類に対する高選択的水素化, 芳香族アルデヒドの異性体の選択的水素化を見い出したほか, 多重修飾層間によるゲラニオールの位置選択水素化, 環状カルボニルのシスートランス選択水素化などに成功した実例を示す。<br>また, われわれはホスト空間の修飾に際して, 触媒活性以外の機能を分担させる目的で導入するチューニングゲストの概念を確立して来たが, この第三のゲスト分子に不斉認識機能を分担させる方法を開拓し, さらに高度な分子認識である不斉認識反応場の開発を試みた。その結果, R-またはS-体のアルキルアンモニウムで不斉修飾した層間が, それぞれS-およびR-体のヘテロ対を形成する不斉認識を見い出した。さらに, 触媒配位子とチューニングゲストのキラリティーのヘテロな組合せ (R-S; S-R) が (-) ネオメントンの水素化により優れた不斉認識機能の発現を認めた。以上の結果から多重認識による高度分子認識触媒への道を提唱した。

Interlayer acid sites were prepared by cation exchange of lithium cations on synthetic taeniolite. Their acidic properties were characterized by means of TPD, FT-IR, NMR and XRD. Catalytic behabior was studied for the dehydration of alcohols and discussed in terms of characteristics of interlayer acid sites.

Intercalation of metal complexes into smectites is one of the useful methods for the preparation of supported metal complex catalysts. Smectites can intercalate metal complexes as well as various organic compounds simultaneously. Multiple modification of clays with these guest compounds (tuning guests) can be applied to the preparation of catalysts for molecular recognition reactions such as shape selective hydrogenation and asymmetric hydrogenation. <BR>In this article, clay-supported metal complexes were prepared by various methods such as cation exchange and ligand exchange methods. For the ligand exchange method, clays were modified with tuning guests including alkylammonium ions and alkylsilanes. These clay-supported catalysts were used for catalytic hydrogenations of alkenes, alkynes, aldehydes, and ketones and their shape selectivities were studied

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 (NH<SUB>3</SUB>) <SUB>4</SUB>] <SUP>2+</SUP>と [Pd (PDT) <SUB>3</SUB>] <SUP>2+</SUP>を用いた。 [PD (NH<SUB>3</SUB>) <SUB>4</SUB>] <SUP>2+</SUP>/LHT (PdAm/LHT) と [Pd (PDT) <SUB>3</SUB>] <SUP>2+</SUP>/LHT (PdPDT/LHT) の底面間隔 (d<SUB>001</SUB>) 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。

Spray reaction method was applied for the preparation of three types of fine particle catalyst. (1) Ni0/MxOy: by reduction of Ni-M-O binary metal oxides to develop super fine Ni0on metal oxide supports; (2) direct preparation of Pd0/ZrO2catalyst by spray reaction; (3) WC fine particles by carbidization of as-sprayed WO3beads. Catalytic properties were studied for the hydrogenation of CO2and cis-2-butene. © 1993, Elsevier Science & Technology.

Hectorite-supported Rh complex catalysts were prepared by the intercalation of RhCl(PPh3)3 into lithium and sodium hectorites in acetonitrile/H2O. The basal spacings of the clay-supported complexes range from 1.8 to 2.2 nm. Shape selective hydrogenation of various aldehydes were carried out by means of these catalysts.