島津 省吾

We successfully prepared Pd-containing perovskite strontium titanate (Pd-STO) by a relatively low-temperature hydrothermal method (i.e., 373 K) without posterior calcination. The particle size and porosity of the STO perovskite could be tuned by changing the molar ratio of H2O/NH3 (e.g., 5.0, 12.5 and 25.0) during the preparation of the amorphous titania sources. The mesoporous contained Pd-STO(12.5) showed superior catalytic performance compared to that of the other Pd-STO(x) (x = H2O/NH3) perovskites for alcohol oxidation with molecular oxygen. Both the refluxing of the non-polar solvents and addition of molecular sieves enhanced the reaction yield significantly. The Pd-incorporated perovskite (Pd-STO) showed better recyclability compared with that of the impregnated perovskite (imp-Pd/STO).

Supported NiO catalysts were prepared by different precursor, support and temperature of the calcination in air. XAFS measurements revealed that Ni-O-Si complex structure formed with NiO nanocluster on catalysts prepared by using [Ni(NH3)6]2+ and SiO2 as a precursor and support, respectively. Coexistence of Ni-O-Si complex structure with NiO nanocluster resulted in the higher activity for 1-phenylethanol oxidation compared to NiO nanocluster only, which indicated that Ni-O-Si complex structure had the promoting effect for this reaction.

A novel preparation method for bimetallic nickel-indium alloy catalysts supported on amorphous alumina (Ni-In(x)/AA x = Ni/In molar ratio) catalysts has been developed and evaluated for the highly selective hydrogenation of biomass-derived furfural. Ni-In(x)/AA catalysts were obtained via the hydrothermal treatment of Raney® nickel supported on aluminium hydroxide (R-Ni/AlOH) and an InCl2·H2O solution in an ethanol/H2O mixture at 423 K for 2 h, followed by reduction with H2 at 573–873 K for 1.5 h. The formation of Ni-In alloy phases such as Ni3In2, Ni3In, Ni2In, and NiIn in Ni-In(2.0)/AA was clearly observed after reduction with H2 at 873 K for 1.5 h. Ni-In(2.0)/AA contained a Ni2In alloy as the major phase, which exhibited the best catalytic performance for the selective hydrogenation of furfural into furfuryl alcohol and was stable for at least five consecutive reaction runs.

A Ni-Y2O3 catalyst containing ruthenium (Ru/Ni-Y2O3) was synthesized and applied to the hydrogenolysis of tetrahydrofurfuryl alcohol (THFA) to produce 1,5-pentanediol (1,5-PeD), which showed superior catalytic performance over that of the Ni-Y2O3 catalyst itself. The optimized ruthenium-containing catalyst, which was prepared by impregnation of 1.0 wt% ruthenium in Ni-Y2O3, showed high catalytic activity for producing 1,5-PeD, giving an 86.5% yield at 93.4% conversion of THFA under 2.0 MPa of H2 at 423K after 40 h. The formation of Ru-Ni0-Y2O3 boundaries was proposed to accelerate the C-O bond scission of the tetrahydrofuran ring to give 1,5-PeD.

Catalytically active and stable catalysts are highly desirable for the acceptorless dehydrogenation (AD) of alcohols. Herein, we developed Cu-Fe catalysts prepared from Cu-Fe layered double hydroxide (LDH) precursors. These Cu-Fe catalysts exhibited outstanding activity and selectivity for the AD of various alcohols under oxidant- and base-free conditions and can be steadily reused for up to 5 consecutive runs with no loss of activity.

Ni-Fe alloy catalysts prepared by a simple hydrothermal method and subsequent H-2 treatment exhibited the greatest activity and selectivity for the hydrogenation of biomass-derived furfural to furfuryl alcohol among the examined second metals, such as Al, Ga, In, Co, and Ti. This work reveals that the alloying of Ni and Fe is a key factor in achieving highly selective hydrogenation of the C=O moiety in unsaturated carbonyl substrates. We found that decreasing the temperature of H-2 treatment (i.e. decreasing the crystallite size), e.g. Ni-Fe(2)HT-573 K (TOF = 952 h(-1)), increased the activity compared to that over Ni-Fe(2)HT-673 (TOF = 375 h(-1)) for furfural hydrogenation. This result suggests that a low-coordinated Ni-Fe alloy was imperative for the catalytic cycle. Moreover, the effect of the metal/support interface was critical; despite the high catalytic performance of Ni-Fe/TiO2, Ni-Fe/Al2O3, and Ni-Fe/CeO2, Ni-Fe supported on SiO2, taeniolite, and hydrotalcite catalysts were ineffective. Vibrational studies using FT-IR measurement confirmed that furfural was physically adsorbed on the surface of the Ni-Fe alloy catalyst via an. eta(1)(O) configuration. The synthetic scope of the Ni-Fe catalytic system was very broad; various types of unsaturated carbonyls, such as unsaturated aromatics, unconjugated aliphatics, and a large substituent, were selectively converted into the corresponding unsaturated alcohols.

The addition of Y2O3 into Ni formed a composite catalyst that selectively produced 1,5-pentanediol rather than 1,2-pentanediol in the hydrogenolysis of furfuryl alcohol at 2.0 MPa H-2 and 423 K. Clearly, 1,5-pentanediol was produced over the Ni-0-Y2O3 boundary. This report highlights the properties of Ni-Y2O3, catalytic performance, and reaction route in the synthesis of 1,5-pentanediol from furfuryl alcohol.

Ni-M (M = Y or La)-catalyzed hydrogenolysis of furfural (FFR) to produce 1,5-pentanediol (1,5-PeD) has been developed through the formation of tetrahydrofurfuryl alcohol (THFA) as an intermediate product. Ni(0)-Y2O3 or Ni(0)-La(OH)(3) composite catalysts executed cleavage of the C-O bond of THFA, giving 1,5-PeD with remarkably high selectivity. Consecutive reactions including hydrogenation of the C=O and C=C bonds and subsequent hydrogenolysis of the C-O bond were performed.

Highly catalytic performance of La2O3 in transfer hydrogenation reactions was achieved following pretreatment involving a sequence of heat treatments under different atmospheric gases. Furfural (FFR) was converted to furfuryl alcohol (FFA) in a very selective manner (98% conversion, with 96% selectivity) using La2O3 that had been calcined under air at 923K and treated under H2 at 673 K. Strongly basic sites and weakly acidic sites were generated after heat pretreatment.

Efficient Ni-Fe alloy catalysts prepared by environmentally friendly method exhibited high selectivity in the hydrogenation of furfural (FFald) to give 95% yield of furfuryl alcohol (FFalc) under 1 MPa of H-2 at 423K using Ni-Fe(2-1) hydrogen treated at 673K catalyst (denoted as Ni-Fe(2-1) HT-673) within 3 h. No significant loss of catalytic activity after 4 running cycles showed a high stability of the catalysts on furfural hydrogenation.

SBA-15 supported Mo oxide catalysts (Mo/SBA) were prepared and the local structures of the Mo species were investigated by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) measurements. The local structure of Mo on Mo/SBA was able to be controlled from T-d monomer to O-h oligomer by increasing the Mo loading. The selectivity of propane photo-oxidation reaction was dependent on the local structure of Mo species. (C) 2015 Elsevier B.V. All rights reserved.

NiO nanocluster catalysts were prepared on a SiO2 support. Ni K-edge XAFS analysis revealed that the combined structure of NiO and Ni-silicate formed by using [Ni(NH3)(6)](2+) as a precursor, whereas pure NiO formed by using Ni-acetylacetonate or Ni-nitrate as a precursor. The obtained NiO nanocluster on Ni-silicate showed the catalytic activity for the oxidative coupling of thiophenol under air atmosphere. The combined structure of NiO and Ni-silicate showed the higher activity than pure NiO nanocluster did.

Mesoporous silica SBA-15 supported NbC catalysts were prepared under reduced pressure of CH4-H-2 gas in a closed circulating system. Nb K- nd L-3-edges XAFS measurements revealed that small NbC cluster formed on SBA-15 support and gradual carburization process by lengthening the carburization temperature-maintaining period. Carburization degree of Nb species was clearly explained by using threshold energy shift of Nb L-3-edge XANES profile.

[Rh(OH)(6)](3-) intercalated Ni-Zn mixed basic salt (Rh/NiZn) acts as an efficient catalyst for the hydrophenylation of internal alkynes with arylboronic acids under mild conditions. The turnover number per Rh site approached 740 in the reaction between 4-octyne and phenylboronic acid. The catalytic monomeric Rh.III) complex is stabilised within the NiZn interlayers, attributable to a strong electrostatic interaction, promoting its re-use.

Efficient hydrogenation of levulinic acid (LA) into gamma-valerolactone (GVL) in water using highly dispersed Ni-Sn(x)/AlOH (x = Ni/Sn ratio) was studied. Increasing the Sn amount in the Ni-Sn alloy up to 2.14 mmol g(-1) enhanced the yield of GVL, which slightly decreased when the Sn content was nearly 4 mmol g(-1) (feeding Ni/Sn = 1.0). A stoichiometric amount of GVL (>99%) was achieved by using Ni-Sn(x)/AlOH (x = 3.0 and 1.4) at 393 K for 120 min in H2O. H-2-treated Ni-Sn(1.4)/AlOH consisting of Ni3Sn2 alloy species showed high selectivity towards GVL (>99% yield). The Ni-Sn(1.4)/AlOH catalyst was reusable for at least six consecutive runs without any significant loss of activity and selectivity.

A highly active and selective hydrogenation of biomass-derived furfural into furfuryl alcohol was achieved using supported single phase Ni3Sn2alloy catalysts. Various supports such as active carbon (AC), γ-Al2O3, Al(OH)3, ZnO, TiO2, ZrO2, MgO, Li-TN, and SiO2have been employed in order to understand the role of the support on the formation of Ni3Sn2aUoy phase and its catalytic performance. Supported Ni3Sn2 alloy catalysts were synthesised via a simple hydrothermal treatment of the mixture of aqueous solution of nickel chloride hexahydrate and ethanol solution of tin(II) chloride dihydrate in presence of ethylene glycol at 423 K for 24 h followed by H2 treatment at 673 K for 1.5 h, then characterised by using ICP-AES, XRD, H2-and N2-adsorption. XRD profiles of samples showed that the Ni3Sn2 alloy phases are readily formed during hydrothermal processes and become clearly observed at 26 = 43-44o after H2 treatment. The presence of Ni3Sn2aUoy species that dispersed on the supports is believed to play a key role in highly active and selective hydrogenation of biomass-derived furfural towards furfuryl alcohol. Ni3Sn2on TiO2and ZnO supports exhibited much lower reaction temperature to achieved &gt 99% yield of furfuryl alcohol product compared with other supports. The effects of loading amount of Ni-Sn, reaction conditions (temperature and time profile) on the activity and selectivity towards the desired product are systematically discussed.

The interlayer spacing of layered Ni-Zn mixed basic salts (NiZn) can be precisely controlled by the intercalation of various long alkyl chain carboxylate anions into the NiZn interlayer. The butyrate-exchanged NiZn (C3H7COO-/NiZn) catalyst effectively promotes the epoxidation of various cyclic enones with aqueous hydrogen peroxide in remarkably high yields. The C3H7COO-/NiZn-catalysed epoxidation of 2-cyclohexen-1-one with an equimolar amount of H2O2 proceeds in a highly efficient manner, with 97% efficiency of H2O2 utilization. This C3H7COO-/NiZn catalyst can be reused without any loss of its catalytic activity and selectivity.

A novel method was applied for the preparation of highly dispersed nickel-tin (Ni-Sn) alloy catalyst supported on aluminium hydroxide using a simple method at a relatively low temperature. The addition of Sn (1.04mmol) on the Raney nickel supported on aluminium hydroxide (R-Ni/AlOH) to form Ni-Sn(3.0)/AlOH (3.0 is Ni/Sn ratio) alloy catalyst remarkably enhanced the selectivity towards hydrogenation of C=O rather than C=C in furfural giving high yield of furfuryl alcohol almost exclusively. The Ni-Sn(3.0)/AlOH (3.0 is Ni/Sn ratio) alloy was also found to be reusable without any significant loss of selectivity for at least six consecutive runs. (C) 2015 The Authors. Published by Elsevier B.V.

Intercalation of an in situ prepared [Rh(OH)(6)](3) complex into an anion exchangeable NiZn layered hydroxy double salt (Rh/NiZn) was demonstrated. The resulting Rh/NiZn effectively catalyzed the 1,4-addition of diverse enones and phenylboronic acids to their corresponding beta-substituted carbonyl compounds. In the case of 2-cyclohexen-1-one and phenylboronic acid, a turnover frequency (TOF) of 920 h1 based on Rh was achieved. The [Rh(OH)(6)](3) complex maintained its original monomeric trivalent state within the NiZn interlayer following catalysis, attributable to a strong electrostatic interaction between the NiZn host and anionic Rh(III) complex.

FeOx-pillared clays (FeOx-pillared bentonite, FeOx-pillared hectorite and FeOx-pillared taeniolite) were synthesized by the intercalation of FeCl3 into clay interlayers and calcination. The synthesized catalysts were exploited for conversion of epoxides furnishing acetonides in good to quantitative yields with short time under mild conditions. The catalysts could be recovered and reused up to five times without appreciable loss of activity. (C) 2014 Elsevier B.V. All rights reserved.

X-ray absorption fine structure (XAFS) and high angle annular dark field scanning transmission electron microscopy (HAADF STEM) were both applied to a characterization of the size regulated Ni nanocluster catalyst on alumina. XAFS analysis showed that NiAl2O4 was not formed in our colloid derived catalyst. The wide variety of coordination number (CN) for Ni-Ni indicated the achievement of the size regulated Ni nanocluster catalyst preparation. HAADF STEM analysis showed narrow size distribution of Ni nanocluster catalyst even after H-2 reduction at 673 K. Distorted particles were observed and the ratio of distorted particles increased with decrease in the cluster size. Water gas shift reaction was carried out to investigate the catalysis. Volcano-shaped size dependence was observed for the activity of supported Ni nanocluster catalyst. (C) 2014 Elsevier B.V. All rights reserved.

A very simple synthetic procedure was developed for the preparation of Ni-Sn alloy catalysts that were uti-lised for chemoselective hydrogenation of furfural, producing furfuryl alcohol almost exclusively. The mix-ture of nickel nanoparticles supported on aluminum hydroxide (R-Ni/AlOH) and a solution containing tin was treated under hydrothermal condition, producing the as prepared nickel-tin alloy supported on alumi-num hydroxide (Ni-Sn/AlOH). H2 treatment at range of temperature of 673-873 K for 1.5 h to the as pre-pared Ni-Sn/AlOH produced nanoporous Ni-Sn alloy catalysts. XRD patterns and SEM images revealed that the formation of Ni-Sn alloy of Ni3Sn and Ni3Sn2 phases and the transformation of crystalline gibbsite and bayerite into amorphous alumina were clearly observed after H2 treatment at 873 K. The formation of the Ni-Sn alloy may have played a key role in the enhancement of the chemoselectivity. © 2014 BCREC UNDIP.

Mo oxide species were prepared on oxide supports and applied for selective photo-oxidation of propane. Mo oxide on mesoporous alumina had a monomeric structure whereas that on mesoporous silica had an oligomeric structure. The main product of the propane photo-oxidation reaction was acetone and propene on Mo oxide monomer unit and on oligomer unit, respectively.

層状構造を持つ無機イオン交換体を触媒担体として用いることで，活性種を層間へ均一に導入することができる<sup>1)</sup>。この方法を用いてわれわれが合成した様々な「層間触媒」は “Intercalation Catalysts” として国際的にも認識されるようになった<sup>2)</sup>。これらの無機化合物の結晶構造や化学的性質を効果的に利用することで，(1)触媒活性種の均一分散と触媒活性の向上，(2)反応空間制御と分子認識性の発現，(3)活性種の立体構造制御と分子認識性の向上，(4)触媒反応補助機能，(5)活性種の安定化などの特長を見いだしてきた。本論文では，われわれが合成して調べた触媒挙動の具体例を取り上げて，層間触媒の特徴を説明する。<br>

Alkaline earth metal titanates ATiO(3) (A: Mg, Ca, Sr, Ba) were prepared from two types of layered potassium titanates [K2Ti2O5 and K0.6Ti1.85O4 (hereafter, Lss)] by using alkaline earth metal molten salts [ACl(2) + A(NO3)(2) (1:1)]. For A = Ca a single phase of perovskite-type compound was prepared at 600 degrees C by using both starting compounds and the reaction temperature was lower than in 400 degrees C that of the solid state reaction with TiO2 (anatase) and CaCO3. A single phase of perovskite-type SrTiO3 was obtained at 600 and 700 degrees C for K2Ti2O5 and Lss, respectively and these temperatures were much lower than that (1200 degrees C) of the solid state reaction with TiO2 (anatase) and SrCO3. In the case of perovskite-type BaTiO3 a single phase of perovskite-type compound was prepared at 700 degrees C by using both starting compounds and also this temperature was much lower than that (above 1300 degrees C) of the solid state reaction with TiO2 (anatase) and BaCO3. Although neither K2Ti2O5 nor Lss could produce a single phase of ilmenite-type MgTiO3, it was prepared by the solid state reaction with TiO2 (anatase) and magnesium basic carbonate at 900 degrees C. A single phase of ilmenite-type CdTiO3 was prepared from K2Ti2O5 by using cadmium molten salts [CdCl2 + Cd(NO3)(2) (1:1)] at 500 degrees C. By taking account of the fact that ilmenite-type CdTiO3 transforms to perovskite-type structure, this preparative method using layered potassium titanates with molten salts preferred to crystallize perovskite-type titanates at lower temperature rather than ilmenite-type ones. (C)2013 The Ceramic Society of Japan. All rights reserved.

Inexpensive Raney Ni-clay composite (R-Ni/clay) catalysts exhibited excellent activity and reusability in the total hydrogenation of biomass-derived furfural into tetrahydrofurfuryl alcohol under mild conditions. For the Raney Ni-bentonite (R-Ni/BNT) catalysts, the complete reaction was achieved at 393 K, 180 min giving almost 99% yield of tetrahydrofurfuryl alcohol. The R-Ni/BNT catalyst was found to be reusable without any significant loss of activity and selectivity for at least six consecutive runs.

Effective production of hexitols (sorbitol and mannitol) was achieved from sugars by means of nickel nano-particles supported on aluminium hydroxide (NiNPs/AlOH) catalyst. NiNPs/AlOH catalyst was prepared by a simple and benign environmentally procedure using less amount of sodium hydroxide. ICP-AES and XRD analyses confirmed that the NiNPs/AlOH catalysts comprised a large amount of remained aluminium hy-droxide (i.e. bayerite and gibbsite). The presence of aluminium hydroxide caused a high dispersion Ni metal species. The average Ni crystallite sizes that derived from the Scherrer's equation for former R-Ni and NiNPs/AlOH were 8.6 nm and 4.1 nm, respectively. The catalyst exhibited high activity and selectivity both hydrogenolysis of disaccharides (sucrose and cellobiose) and monosaccharides (glucose, fructose, and xylose) at 403 K for 24 h. The NiNPs/AlOH catalyst was found to be reusable for at least five consecutive runs without any significant loss of activity and selectivity. © 2013 BCREC UNDIP.

A series of Pd-incorporated titanate catalysts (Pd/KSTO) were synthesized by the intercalation of Pd(NO3)(2) into layered potassium titanate (KTO), which proceeded via a cation-exchange reaction in molten salts. Perovskite phases of Pd/KSTO for catalysis were synthesized at 600 degrees C and above, whereas a lepidocrocite-type layered titanate structure, similar to that of the parent KTO, was retained when a lower temperature of 400 degrees C was used during synthesis. In both cases, the Pd species exists as divalent Pd. The synthesized Pd/KSTO catalysts were then applied to the liquid-phase oxidation of alcohols using molecular oxygen without any additives. The perovskite-type Pd/KSTO catalyst displayed superior activity when compared to that of the lepidocrocite-type, yielding a high turnover number of 800 in the aerobic oxidation of 1-phenylethanol with no loss of catalytic activity after three runs in catalyst recycling experiments.

Three types of Co-porphyrin complexes differing in their porphyrin-ring substituents and nonionic or cationic structure were intercalated into lithium taeniolite (LiTN) using a simple cation exchange method. All the intercalated catalysts displayed expanded clearance spaces (in the range of 0.30-0.51 nm) compared with that of the parent LiTN (0.24 nm). The catalysts were applied for the oxidative cleavage of isoeugenol to vanillin with molecular oxygen as the sole oxidant, and the reaction proceeded effectively under mild reaction conditions. The highest vanillin selectivity of 72% was obtained with CoTPyP/TN, which had the widest clearance space among the three Co-porphyrin catalysts. These intercalated catalysts showed high stability during oxidation, enabling their recycling for at least three runs. (c) 2012 Elsevier B.V. All rights reserved.

A novel method was applied for the preparation of Ni-Sn alloy catalysts that were utilized for chemoselective hydrogenation of unsaturated carbonyl compounds, producing unsaturated alcohols almost exclusively. The formation of the Ni-Sn alloy may have played a key role in the enhancement of the chemoselectivity.

The aerobic oxidation of alpha-hydroxy ketones into alpha-diketones catalyzed by CaO is compared with the same reaction catalyzed by other metal oxides. The catalytic activities of the various metal oxides were proportional to their surface basicities. The direct conversion of alpha-hydroxy ketones into quinoxalines via CaO-catalyzed aerobic oxidation followed by in situ reaction with 1,2-diaminoaromatics is also achieved. Various types of quinoxalines were synthesized in the presence of the CaO catalyst and molecular oxygen. It was also found that the CaO catalyst was reusable without any loss of its catalytic activity.

The structure of allophane heat-treated at 623, 773, and 973 K was characterized by Al-27 cross-polarization magic-angle-spinning (CP-MAS) and Al-27 multiple-quantum magic-angle-spinning (MQMAS) NMR. From these spectra, the structural change of allophane was observed over 623 K, i.e., the formation of five-coordinated Al from the original six-coordinated Al in allophane was confirmed after heat treatment. We concluded that Al atoms in the five-coordinated species have been formed by the OH elimination from six-coordinated Al in allophane. In addition, aluminosilicate layer deformation also took place to form silica and alumina thin layers separately. The results of P-31 MAS NMR studies indicate the Lewis acid sites rather than Bronsted acid sites increased with a rise in the treatment temperature.

Currently, environmental pollution and a diminishing supply of fossil resources are the key issues that have led to the search for alternative carbon resources. Fossil fuels still dominate energy consumption, with a market share of 87%. Renewable energy continues to increase, but today it accounts for only 2% of the global energy consumption. It has been proposed that commodity chemicals derived from fossil resources will inevitably be available from renewable resources such as plant-derived lignocellulose and other related compounds. These commodity chemicals will eventually be obtained from lignocellulosic materials, which are the main component of biomass, using biorefinery techniques. The global storage of biomass corresponds to 60% of the global primary energy supply per year. Various chemical transformation processes, such as gasification and hydrolysis in different media, are introduced in the present review.

A series of tris(β-diketonato)zirconium(IV) complexes was immobilized into a synthetic clay structure of Taeniolite by an ion-exchange method to generate organic/inorganic hybrid compounds. The hybrid compound served as a good catalyst for ring-opening reactions of methyl, ethyl, and dimethyl oxiranes with various alcohols to generate primary alkoxy alcohols in appreciable selectivity. This method describes a technique to immobilize cationic zirconium complexes without losing selectivity. © 2012 Published by LPPM ITB.

Clay-intercalated Sn catalysts were prepared by a conventional cation-exchange method and used for the Baeyer-Villiger oxidation of various ketones with hydrogen peroxide as an oxidant. The intercalation of monomeric Sn species into the clay interlayer was monitored by solid-state Li-7 MAS NMR. Solid-state Sn-119 MAS NMR and Sn K-edge XAFS analysis revealed that an isolated Sn species, such as [Sn-IV(OH)(x)(H2O)(5-x)]((4-x)+) (x = 0 3), was formed in the clay interlayers. Our clay-intercalated Sn catalysts showed extremely high performance in Bayer-Villiger oxidation and were also reusable without any significant loss of activity or selectivity.

Inexpensive Ni-Sn-based alloy catalysts, both bulk and supported, exhibited high selectivity in the hydrogenation of a wide range of unsaturated carbonyl compounds and produced unsaturated alcohols almost exclusively. For the bulk Ni-Sn alloy catalysts, a relatively high reaction temperature of 453 K was required to achieve an efficient hydrogenation of C=O rather than C=C. The catalyst that consisted of the Ni-Sn alloy dispersed on TiO2 allowed a remarkable reduction of the reaction temperature to 383 K. Both the Ni3Sn2 and Ni3Sn alloy phases were found to be responsible for the enhancement of the chemoselectivity. The Ni-Sn alloy catalysts were reusable without any significant loss of selectivity.

The structure of imogolite treated at 623, 773, and 973 K was characterized by Al-27 MAS and Al-27 multiple-quantum magic-angle-spinning (MQMAS) NMR. For comparison, Al-27 NMR spectra of imogolites, allophanes, and kaolinite heated at 623, 773, and 973 K were acquired to investigate the structural change of these clay minerals. From these spectra, the structural change of imogolite has been observed at 623 K as well as in the case of allophane, while that of kaolinite has been demonstrated at a higher temperature of 773 K. The formation of five-coordinated Al from the original six-coordinated Al in imogolite after heat-treatment was confirmed as well as in the case of kaolinite and allophane. Furthermore it is found that the peaks for five- and four-coordinated Al of imogolite shifted to lower field and that their quadrupolar products (P-Q) increased with treated temperature. It can be concluded that the five- and four-coordinated Al species are generated from the decomposition of six-coordinated Al. The chemical shifts of all peaks above 623 K indicate the increase of the structural strain in the heat-treated imogolite and the formation of amorphous phases by the decomposition of the original tubular structure.

Typical biomass in Japan (bamboo, Japanese cedar and rice straw) were decomposed by using sulfonated allophane catalyst and hemicellulose in bamboo was preferentially decomposed to xylose. The maximum xylose yield was 40.9% (on the base of hemicellulose) in the reaction at 150 degrees C for 4.0 h. Mannose and xylose were mainly produced from Japanese cedar and arabinose was mainly produced from rice straw. (C) 2010 Elsevier B. V. All rights reserved.

Silica-supported Pd nanoparticles (Pd/SiO2) with dimethyl sulfoxide (DMSO) show excellent catalytic activity and selectivity for the semihydrogenation of alkynes. Small amounts of DMSO drastically suppress the overhydrogenation and isomerization of alkenes. This catalyst system is also applicable to both internal and terminal alkynes. Furthermore, the Pd/SiO2 catalyst was separable from the reaction mixture after the hydrogenation and reusable without loss of its high catalytic activity or selectivity.

An anionic D-valine-Pd(II) complex intercalated into an anion exchangeable Ni-Zn mixed basic salt (NiZn), which is classified as a layered hydroxy double salt, was synthesised in situ via a simple anion exchange procedure. A Bronsted basic PO(4)(3-) anion was also intercalated into the NiZn interlayer along with the anionic D-valine-Pd(II) complex. The Bronsted basic clay-Pd(II) nanocomposite catalysed the aerobic oxidation of a wide variety of alcohols to the corresponding aldehydes and ketones. In the aerobic oxidation of 1-phenylethanol, for example, a turnover number (TON) of 2000 based on Pd was achieved. During the aerobic alcohol oxidation, the D-valine-Pd(II) complex in the NiZn interlayer maintained its original monomeric Pd(II) structure due to the strong electrostatic interaction between the NiZn host and the anionic Pd(II) complex. This catalyst could be reused without loss of either catalytic activity or selectivity for the aerobic oxidation of alcohols.

Fine control of the formation of Pd-0 nanoparticles with diameters between 1 and 1.5 nm on hydroxyapatite (HAP) was achieved by adjusting the temperature at which the Pd-II species on the HAP surface (Pd(II)HAP) was reduced in the presence of 1 atm of molecular hydrogen. The HAP-supported Pd-0 nanoparticles (Pd(0)HAP) having an average diameter of 1.5 nm exhibited significantly high catalytic activity for the regioselective hydrogenation of quinolines to the corresponding 1,2,3,4-tetrahydroquinolines under mild reaction conditions. Moreover, the Pd(0)HAP catalyst was reusable without appreciable loss of its high catalytic activity or selectivity.

The interlayer space of layered Ni-Zn mixed basic salt (NiZn) can be controlled precisely by the intercalation of various carboxylate anions with long alkyl chains via simple anion exchange. Expansion of interlayer space in the anion-exchanged NiZn depends on the alkyl chain lengths of pillar molecules. The butyrate anion-exchanged NiZn (C3H7COO-/NiZn) catalyst promoted effectively various base-catalyzed Knoevenagel reactions in water with remarkably high yield. This C3H7COO-/NiZn catalyst was reusable without any loss of catalytic activity or selectivity.

Complete hydrodechlorination of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) and its derivatives 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (DDE) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD) was achieved using a hydroxyapatite-supported Pd nanoparticle catalyst (Pd(0)HAP) in the presence of molecular hydrogen under mild reaction conditions. The catalytic activity of Pd(0)HAP was significantly higher than those of previously reported Pd catalysts.

Bamboo biomass was hydrolyzed by using sulfonated allophane catalyst and hemicellulose in bamboo was preferentially decomposed to xylose and xylo-oligosaccharides in the range from 130 to 160 degrees C.

Supported NbN catalysts were prepared under a N(2)-H(2) gas stream by the addition of Fe species to Nb/SiO(2). The nitriding process was monitored by in situ XAFS measurements. Fe K-edge XAFS and Nb K-edge in situ XAFS measurements revealed that Fe species in close proximity to niobium oxide can effectively induce nitridation of the niobium oxide with the nitriding rate being dependent upon the dispersion of Fe species. It was concluded that the dispersed Fe species close to niobium effectively assisted the nitridation of niobium oxide into NbN. The nitriding degree can be expressed by the coordination number of Nb-N.

CuMn-spinel oxide (CuMn(S)) and non-spinel CuMn (CuMn(NS)) oxide have been obtained by calcining the same precursor at 900 degrees C and 300 degrees C, respectively. CuMn(S) was composed of Cu(1.5)Mn(1.5)O(4) spinel and Mn(3)O(4), while CuMn(NS) consisted of CuO and Mn(3)O(4). XRD, EXAFS, and TEM measurements of the samples reduced in hydrogen revealed that both CuMn(S) and CuMn(NS) were reduced to Cu metal dispersed on MnO and that the particle size of Cu metal from the CuMn(S) was smaller than that from CuMn(NS). In methanol steam reforming, the spinel derived catalyst showed higher activity than the non-spinel due to the higher dispersion of the Cu metal. (c) 2009 Elsevier B.V. All rights reserved.

SiO2-Supported Fe-NbN catalysts were prepared by temperature programmed reaction (TPR) method from Fe-Nb/SiO2 oxide precursor under a N-2-H-2 gas stream. As raising the intermediate temperature-maintaining (ITM) step temperature during the TPR, Fe species in the Fe-Nb/SiO2 catalyst was reduced to zero-valent, confirmed by Fe K-edge XAFS analysis. Although the Fe-Fe coordination number increased by elevating ITM temperature, the size of Fe cluster was still small. The Nb-N coordination number became larger, as higher the ITM temperature. The reduced Fe species effectively assisted the nitridation process of Nb.