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Direct esterification of succinic acid with phenol in the presence of zeolite catalysts was explored. H+-zeolite β (SiO2/Al2O3 = 150) has emerged as the most effective solid acid catalyst, affording 96% yield of diphenyl succinate. The catalyst could be recycled upon 5 consecutive runs without appreciable decreases in activity. Additionally, the catalyst was successfully applied to the esterification of several dicarboxylic acids with phenol producing good and moderate yields of the desired products. The proposed method not only offers essential features of the heterogeneous systems but also brings simplicity in operation, makes it more economical and environmentally-friendly.

Formic acid can be used as a hydrogen source for the hydrogenations of various aromatic carbonyl and nitrile compounds into their corresponding alcohols and amines using reusable heterogeneous Pd/carbon and Pd/Al2O3 catalysts, respectively, under additive-free and mild reaction conditions.

Transformation of C5 furaldehydes to the corresponding C6 furaldehydes over a heterogeneous catalyst is a versatile but demanding reaction process. This report describes our discovery that Amberlyst-15, a conventional sulfuric functionalized resin, affords a 43.1% yield for 5-hydroxymethyl-2-furaldehyde (HMF) production with 57.5% selectivity via direct hydroxymethylation of 2-furaldehyde (furfural) with an aqueous formaldehyde reagent. This report is the first to describe an important achievement on the heterogeneous acid catalyst-assisted HMF production from furfural via direct hydroxymethylation in a batch reactor system. The Amberlyst-15 was also reusable and applicable for C5 furaldehyde upgrading of various types: furfuryl alcohol, furfurylamine, and furoic acid toward the corresponding C6 furaldehydes. Results show that a liquid flow system becomes an advanced tool for the continuous production of upgrading furaldehydes through a fixed Amberlyst-15 catalyst bed. Accordingly, the sulfuric functionalized resin-catalyzed direct hydroxymethylation of furaldehydes with aqueous formaldehyde in both batch and flow reactor systems is worthwhile and opens up new avenues for biomass transformations in particles, an important area of inedible biomass utilization.

The effects of SiO2 amount on the base catalysis of highly active finely crystallized Mg–Al type layered double hydroxides prepared by the co-precipitation method with coexistence of SiO2 spheres, denoted as SiO2@LDHs, were investigated. With the Si/(Mg + Al) atomic ratios of 0–0.50, the highest activity for the Knoevenagel condensation was observed in the case of Si/(Mg + Al) = 0.17, as the reaction rate of 171.1 mmol g(cat)−1 h−1. The base activity increased concomitantly with decreasing LDH crystallite size up to Si/(Mg + Al) atomic ratio of 0.17. However, above the Si/(Mg + Al) atomic ratio of 0.17, the reaction rate and TOFbase were decreased although the total base amount was increased. Results of TEM-EDS and 29Si CP-MAS NMR suggest that the co-existing SiO2 causes advantages for dispersion and reduction of the LDH crystallite to improve the base catalysis of SiO2@Mg–Al LDH, whereas the excess SiO2 species unfortunately poisons the highly active sites on the finely crystallized LDH crystals above a Si/(Mg + Al) atomic ratio of 0.17. According to these results, we inferred that the amount of spherical SiO2 seeds in the co-precipitation method is an important factor to increase the base catalysis of SiO2@LDHs; i.e. the control of Si/(Mg + Al) atomic ratio is necessary to avoid the poisoning of highly active base sites on the LDH crystal.

Au nanoparticles supported on alumina (Au/Al2O3) with average particle size of 3.9 ± 0.7 nm and surface plasmon band centerned at 516.5 nm were prepared by deposition–precipitation method, and their photocatalytic activities for the reduction of nitrobenzene using either formic acid in acetonitrile (method A) or KOH in 2-propanol (method B) were investigated. Even at room temperature, the Au/Al2O3 was found to be highly active and selective for conversion of nitrobenzene to aniline when used with formic acid in acetonitrile or to azobenzene when performed with KOH in 2-propanol under irradiation with green light-emitting diode (517 nm).

Transformations of furaldehydes to the corresponding furfuryl alcohols via hydrogenation with sodium hypophosphite (NaH2PO2) as a hydrogen donor agent were performed over Pd/Al2O3 catalyst under ambient condition in THF/water solvent. Furfuryl alcohol (FOL), 5-methylfurfuryl alcohol (5-MFOL) and 2,5-bis(hydroxymethyl)furan (BHMF), were produced with 68%, 45% and 63% yield, respectively, from 2-furaldehyde (furfural), 5-methylfulaldehyde (5-MF) and 5-hydroxymethyl-2-furaldehyde (HMF) at room temperature (25 °C). The Pd/Al2O3 catalyst was reusable for all reaction without significant decrease in activity. These results indicated that the NaH2PO2 would be a cheap and an easy-handling hydrogen donor for catalytic hydrogenation reactions under mild conditions.

A hydrotalcite-supported palladium chloride (PdCl2/HT) catalyst has been developed for the Suzuki–Miyaura coupling (SMC) reaction. As-prepared PdCl2/HT effectively catalyzed the SMC reaction of bromobenzene under air to afford >99 % biphenyl yields and the catalyst could be reused without any significant loss in catalytic activity. The moderate activity (69 % biphenyl yields) of the PdCl2/HT catalyst for chlorobenzene was improved, resulting in biphenyl yields of up to 96 % using a surfactant as an additive. Among various surfactants employed, Triton X-100 (TX-100) enhanced the catalytic performances of PdCl2/HT the most. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) of bare and surfactant-treated PdCl2/HT catalysts depicted the ligation of the Pd species by TX-100 influenced the electronic structure of the Pd species, leading to efficient catalysis.

Fine-crystallized layered double hydroxides are prepared via the co-precipitation method with the coexistence of SiO2 spheres (SiO2@LDH), and their base catalysis and structural properties are investigated. The as-prepared SiO2@LDHs exhibit higher base catalysis for the Knoevenagel condensation than conventional LDHs prepared via the co-precipitation method in the absence of SiO2 spheres. Such an increase in the activity for base catalysis is also observed in various types of SiO2@LDHs with different metal compositions (M2+: Mg2+ or Ni2+, M3+: Al3+ or Ga3+, and M2+/M3+: 1 or 3). X-ray diffraction (XRD) measurement suggests that the addition of SiO2 induces decreases in the LDH crystallite size. The results of transmission electron microscopy – energy dispersive X-ray spectroscopy (TEM-EDS) and 29Si cross polarization magic angle spinning nuclear magnetic resonance (29Si CP-MAS NMR) on SiO2@Mg–Al LDH suggest that the crystals of Mg–Al LDH are immobilized on the SiO2 surface through Si–O–Al and Si–O–Mg covalent bonds. According to these results, we conclude that the co-precipitation method in the presence of colloidal spherical SiO2 seeds, particularly possessing a 40 nm diameter, result in highly-dispersed points of LDH crystal growth on the SiO2 surface, which lead to the generation of fine-crystallized highly active LDH nanocrystals.

Achievements in advanced materials science have required close cooperation with innovations in nanotechnology. First, in this Minireview, two impressive examples of close relationships between materials science and nanotechnology are introduced by using the histories on the Lycuurgus Cup and H2 storage/release phenomena in Pd crystals. In the main sections, the recent advanced approaches and the impressive scope of size- and shape-controlled precious monometallic nanoparticle catalysts and the recent advances in organic-stabilizer-mediated specific catalysis are introduced. Heterogeneous catalysis is susceptible to nanoscale surface functionality and morphology, therefore, significant research has been directed towards controlled nanostructured catalysis associated with new nanotechnology for synthesis and analysis techniques. These discussions are with a view for future innovations in catalysis combined with nanotechnology.

Pyrolysis bio-oil is a promising source of liquid fuels, but requires upgrading to remove excess oxygen and produce a satisfactory fuel oil. Nickel phosphide has been shown to be an active composition for hydrodeoxygenation (HDO) of bio-oil model compounds. In this study, nickel phosphide catalysts were used for direct upgrading of an actual pyrolysis bio-oil derived from cedar chips. The activity of Ni2P deposited on an amorphous SiO2 support for HDO was first verified using the model compound, 2-methyltetrahydrofuran (2-MTHF), at the temperature of the pyrolysis oil treatment of 350 °C. The Ni2P/SiO2 catalyst showed high activity for 2-MTHF hydrodeoxygenation under atmospheric pressure hydrogen with low cracking activity. Fast pyrolysis and catalytic upgrading were conducted sequentially using a laboratory-scale, two-stage system consisting of a fluidized bed pyrolyzer and a fluidized bed catalytic reactor both operating at 0.1 MPa, with a hydrogen partial pressure of 0.06 MPa. It was found that the Ni2P/SiO2 catalyst was moderately effective in upgrading the biomass pyrolysis vapors and producing a refined bio-oil with decreased oxygen content. The moderate deoxygenation of the bio-oil was confirmed by elemental analysis and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Gas chromatography–mass spectrometry (GC–MS) analysis showed that the treated bio-oil mainly consisted of phenolic compounds, and the MS spectra before and after upgrading suggested that reactions including hydrodeoxygenation, hydrogenation, decarbonylation, and hydrolysis occurred during the upgrading. Furthermore, Ni2P supported on ZSM-5 zeolite eliminated oxygen in the bio-oil with smaller reduction in the oil yield than Ni2P supported on SiO2. The deoxygenation activity of the nickel phosphide catalysts was higher than that of conventional catalysts such as Ni/SiO2, Pd/C and an FCC-catalyst.

Selective intramolecular aldol condensation of 2,5-hexanedione (HD), which is producible from 5-hydroxymethyl-2-furaldehyde (HMF) via hydrogenolysis and successive hydrolysis, towards 3-methyl-2-cyclopentenone (MCP) is examined with various solid acid catalysts. It is found out that the simple aluminum oxides such as γ-Al2O3 and AlOOH gave an attractive performance for the MCP generation from HD with high selectivity (>71%). After the hydrothermal treatment for 6 h on γ-Al2O3 to modify its acidity, it is found that as-prepared γ-Al2O3/AlOOH nanocomposite exhibits the yield of 77.2% with the highest selectivity of 85.9% for MCP.

The effects of SiO

Solid base catalysts were studied for the first time to synthesize N-hydroxysuccinimide (NHS) through the reaction of succinic acid with hydroxylammonium chloride. The highest yield of 42% (±3%) with 65% (±4%) selectivity toward NHS production was achieved by using Amberlyst A21, which is a weak base anion-exchange resin. The present catalyst could be recycled during five runs without significant decreases in activity. Also, efficacy for the Amberlyst A21 mediated reaction was also explored with other dicarboxylic acids such as phthalic acid, glutaric acid, and maleic acid.

Poly(N-vinyl-2-pyrrolidone)-capped ruthenium-supported hydroxyapatite (Ru-PVP/HAP) shows significant activity for the synthesis of furfurylamine (FAM) via the reductive amination of furfural. As-prepared 5 wt% Ru-PVP/HAP affords 50 % yield of FAM in 25 % NH3 aqueous solution under pressurized H2 gas (2.5 atm), and the highest yield approaches 60 % at 4.0 H2 atm. Comparison between the activities over four Ru-supported HAP catalysts prepared with different methods and the results of X-ray absorption spectroscopy suggested that the metallic Ru cluster is the active center for the reductive amination of furfural. Transmission electron microscope and inductively-coupled plasma analysis indicated that the as-prepared 5 wt% Ru-PVP/HAP catalyst possessed 4.0 wt% PVP-capped Ru clusters with average diameter of 1.7 ± 0.3 nm on HAP support. It was also demonstrated that the reductive amination approach with Ru-PVP/HAP catalyst, NH3 aq. and pressurized H2 gas has capability for transformation of aromatic aldehydes to the corresponding aromatic amines. According to these results, it is concluded that Ru(0) cluster supported on HAP will represent a suitable catalyst for widely-usable reductive amination to convert an aldehyde functionality towards an amine.

Herein, we discuss a convenient surfactant-mediated hydrothermal approach to control supported copper oxide species in a highly reproducible way and investigate their effect on the catalytic upgrading of glucose to lactic acid. Careful characterization using XRD, Raman spectroscopy, and temperature programmed reduction (TPR) studies revealed paramelaconite (Cu4O3) loaded on MgO as the catalytically active species. It was also found that the cuprite (Cu2O) phase can be prepared in the presence of N,N-dimethyldodecylamine N-oxide (DDAO) while the tenorite (CuO) phase was obtained in the absence of surfactant. The use of cetyltrimethylammonium bromide (CTAB) selectively gave the Cu4O3 phase as the supported species. The above-mentioned systematic approach demonstrates that substantial improvement in the catalytic activity (or other properties) can be achieved by careful selection of the synthetic conditions for generation of desired Cu species through a simple and inexpensive preparation route.

Bimetallic CoPd nanoparticles (NPs) on boehmite (AlOOH) were synthesized under hydrothermal conditions using three different capping agents for the facile utilization of formic acid (FA) as a hydrogen source. The CoPd NPs capped with N,N-dimethyldodecylamine N-oxide (DDAO) supported on AlOOH (CoPd-DDAO/AlOOH) exhibited superior catalysis and recyclability in the hydrogenation of maleic anhydride (MAn) in water without metal leaching. The formation of monodispersed CoPd-DDAO NPs on AlOOH that contained both cobalt oxides and CoPd alloy in each NP was indicated by TEM with energy-dispersive spectroscopy, XRD, and X-ray absorption spectroscopy (XAS) studies. X-ray photoelectron spectroscopy and XAS supported the partial electron transfer phenomenon in CoPd-DDAO NPs. The as-prepared CoPd-DDAO/AlOOH catalyst showed activity for the utilization of FA formed in situ from biomass for the hydrogenation of MAn. It suggested that the DDAO capping agent contributed strongly to the favorable electronic/geometric changes in CoPd alloy for the facile utilization of FA.

Three kinds of oligo-ladder polyphenylsilsesquioxanes were synthesized by two unique methods through the aqueous–organic boundary reaction via octahedrally-coordinated pyridine–silicon adduct PhSiCl3(Py)2, which is formed from trichlorophenylsilane (TCP) monomer and pyridine in n-propyl acetate. When two equivalent pyridines to TCP were used, SQ polymer-1 was formed as a viscous solid, which was recrystallized in n-hexane to obtain SQ polymer-2B. When an excess pyridine was used (pyridine/Si = 10), SQ polymer-2A was directly obtained as a white solid. MALDI–TOF/TOF–MS, FT-IR and 29SiNMR clearly shows that the “Ladder” structure of SQ polymers is dominant in both methods. It was shown that in this one-pot synthesis, SQ polymer structure was controlled by pyridine amount. Furthermore, MO simulation of pyridine adduct formation (PhSiCl3(Py)2) supports the hydrolysis pathway for synthesis as well as the “Ladder” structure formation. Finally, it was also suggested that the hydrolysis reaction occurred in a stepwise manner.

Selective oxidation of 1,6-hexanediol into 6-hydroxycaproic acid was achieved over hydrotalcite-supported Au-Pd bimetallic nanoparticles as heterogeneous catalyst using aqueous H2 O2 . N,N-dimethyldodecylamine N-oxide (DDAO) was used as an efficient capping agent. Spectroscopic analyses by UV/Vis, TEM, XPS, and X-ray absorption spectroscopy suggested that interactions between gold and palladium atoms are responsible for the high activity of the reusable Au40 Pd60 -DDAO/HT catalyst.

Formic acid (FA) can be synthesized from monosaccharides such as glucose, galactose, xylose, arabinose and lyxose by using both calcined Mg-Al hydrotalcite as a solid catalyst and aqueous H2O2 as an oxidant in ethanol solvent at 343 K for 5 h. For the glucose oxidation, the FA yield and H2O2 utilization efficiency reach 78% and 100%, respectively. The used hydrotalcite catalyst can be easily separated from the reaction mixture and is reusable at least twice.

a b s t r a c t Design of a suitable catalyst for the conversion of inedible-biomass, a renewable resource, into highvalue chemicals is an immense and important area of research in an era of energy crisis. This paper demonstrates batch conversion of sugars into lactic acid (LA) and formic acid (FA) employing a supported copper catalyst. A magnesia-supported copper catalyst was synthesized by a hydrothermal methodology using CTAB as the capping agent (denoted as CuCTAB/MgO). We found that the CuCTAB/MgO not only dramatically boosted the yields of LA and FA from sugars but also decreased the energy demand of the process by decreasing the reaction temperature from 523 K to 393 K. The high yields of LA (70%) in the presence of NaOH and of FA (65%) in the presence of H2O2 were achieved from glucose at 393 K in water using a CuCTAB/MgO catalyst, which could be recycled without any significant loss of activity. The copper catalyst was also found to exhibit excellent activity for the transformation of other sugars. The catalyst was characterized using PXRD, H2-TPR, N2 adsorption–desorption, and other analytical techniques to investigate the active Cu species and propose a plausible mechanistic pathway to LA.

Hydrotalcite-supported gold nanoparticles show good activity as a heterogeneous catalyst for the oxidation of monosaccharides (xylose, ribose, galactose and mannose) and disaccharides (lactose and cellobiose) into the corresponding sugar acids under external base-free conditions in water solvent using atmospheric pressure of molecular oxygen. The produced sugar acids were thoroughly identified by 1H-, 13C-, and HMQC-NMR and ESI-FT-ICR MS spectroscopic techniques.

The aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) was investigated over hydrotalcite (HT)-supported various catalysts composed of PVP-capped Au, Pd, or Pt....

Furfural was effectively synthesized from xylose in a one-pot manner by the combined use of Ni2+-modified γ-Al2O3 (Al2O3–Ni-Al layered double hydroxide (LDH)) and a sulfonated resin (Amberlyst-15) ...

Hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) was examined by PdxAuy/C catalysts prepared with various Pd/Au molar ratio (x/y) in the presence of hydrochloric acid (HCl) under an atmospheric hydrogen pressure. Bimetallic PdxAuy/C catalysts had a significant activity for a selective hydrogenation of HMF toward DMF comparing to monometallic Pd/C and Au/C catalysts. To clarify the novelty of PdxAuy/C catalysts, characterizations by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectra (XAFS), a transmission electron microscopy (TEM) and other analytical techniques were studied. XPS and X-ray absorption near-edge structure (XANES) analyses indicated that there was the charge transfer phenomenon from Pd to Au atoms in PdxAuy/C. Existence of PdAu alloy structures in PdxAuy/C was expected by XRD, TEM and extended X-ray absorption fine structure (EXAFS) analyses. Accordingly, we concluded that PdAu alloys supported carbon exhibited a good catalytic performance for a selective hydrogenation of HMF to DMF using an atmospheric hydrogen pressure.

The effect of stabilizing polymers such as starch, PVP, and PVA on catalysis of hydrotalcite-supported platinum nanoparticles (Pt–polymer/HT) for the base-free aerobic oxidation of 1,2-propanediol (PG) in aqueous solution using molecular oxygen under atmospheric pressure at room temperature (RT), electronic state, and hydrophilicity was investigated. The particle size of supported Pt naoparticles (NPs) was controlled to be the same (ca. 2.2 nm) by changing polymer amount during the preparation of Pt NPs. The Pt–starch/HT exhibited the higher activity than the Pt–PVP/HT and Pt–PVA/HT for oxidation of the primary hydroxyl group of PG toward lactic acid (LA). Pt 4f XPS and Pt L3-edge XANES analyses suggested that Pt atoms in Pt NPs stabilized by starch and PVA were more negative than that stabilized by PVP. Furthermore, the measurement of water contact angle suggested that Pt–starch/HT and Pt–PVA/HT had less hydrophilic nature than that of Pt–PVP/HT. These results indicate that the polymer plays an important...

One-pot synthesis of (2-furanylmethylene)malononitrile, a Knoevenagel product of furfural with malononitrile, from xylose efficiently proceeded by combined use of acid Amberlyst-15 and acid-base Cr/hydrotalcites in 44% yield. Structural characterization was carried out using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and nitrogen adsorption measurements. The Lewis acidic properties of the highly active Cr/HT were investigated using the Meerwein–Ponndorf–Verley (MPV) reaction. It was confirmed that the prepared Cr/HT possessed the Lewis acid Cr2O3 on the HT surface. Thus, combined use of the dispersed Lewis acid Cr2O3 and the Bronsted base HT facilitated the isomerization step of aldose into ketose and strongly promoted activity for the synthesis of furfural derivatives from aldoses through isomerization, dehydration and Knoevenagel condensation reactions in a one-pot manner.

The design of a highly active and stable heterogeneous palladium catalyst is gaining a lot of attention because of its increasing importance in the organic syntheses of commodity chemicals. Herein, we report the tailored synthesis of palladium species grafted on a highly stable amino functionalized organozinc coordination polymer (denoted as Pd/AZC) and its extraordinary catalytic performances in the Suzuki–Miyaura coupling (SMC) reaction. It achieved the highest turnover number of 2 106 720 (>99% yield) in air among the most reported palladium catalysts for the SMC reaction of bromobenzene. The as-prepared Pd/AZC composite is also successfully applied for the catalysis of Mizoroki–Heck coupling, hydrogenation of nitro, and –CC– functional groups. Since the developed AZC support has thermal stability at least up to 573 K, it possesses high potential for grafting various metal species as catalytically active centers for a wide range of metal-catalyzed reactions.

A new approach is developed for hydrogenolytic ring opening of biobased 5-hydroxymethylfurfural (HMF), dehydration product of hexoses, towards 1,6-hexanediol (HDO) under atmospheric pressure. The highest yield of HDO, 43%, is achieved over reusable Pd/zirconium phosphate (ZrP) catalyst at 413 K in the presence of formic acid as hydrogen source. In comparison with various Brønsted and/or Lewis acidic supports, the specific Brønsted acidity on ZrP support effectively accelerated the cleavage of C-O bond in a furan ring.

In this research, zirconium compounds were prepared as water-tolerant solid base catalysts by a simple method. Their catalytic activities were investigated in the aqueous glucose–fructose isomerization reaction. The zirconium carbonate (ZrC) catalyst could work in wide range of reaction temperature (80–140 °C) and the maximum glucose conversion reached 45 % at 120 °C with 76 % selectivity to fructose. The ZrC catalyst was found to retain its activity without significant decrease in the fructose yield after being used for five times. In the one-pot transformation of glucose to levulinic acid (LA), the ZrC could afford 17 % yield of LA after 12 h reaction in water–toluene biphasic solvents in combination with a solid acid catalyst, Amberlyst-15. The proposed reaction system in water–toluene biphasic solvents occurred faster and gave higher LA yield than that in pure water solvent.

As-prepared platinum/gold alloy nanoparticles-supported hydrotalcites (PtxAuy–starch/HTs) by using a soluble starch as a green reducing and a stabilizing agent are found to be truly effective heterogeneous catalysts for the selective aerobic oxidation of glycerol (GLY) and 1,2-propanediol (PG) in base-free aqueous solution using molecular oxygen in atmospheric pressure at room temperature. The PtxAuy–starch/HTs exhibited higher selectivities for oxidation of the primary hydroxyl group in GLY and PG toward glyceric acid (GA) and lactic acid (LA), respectively, with molecular oxygen in aqueous solution than those reactions over monometallic Pt–starch/HT or Au–starch/HT. Pt60Au40–starch/HT was found to be the most active catalyst for selective aerobic oxidation of polyols. It showed 73% GLY conversion with 57% GA yield and 63% PG conversion with 47% LA yield and retained high selectivity in recycling experiments. XRD patterns of the PtxAuy–starch NPs indicated the d-spacing of Pt atoms was changed by alloyin...

The golden wonder: Various α-amino acids such as glucosaminic acid, galactosaminic acid, or N-acetyl-glucosaminic acid can be obtained from the corresponding glucosamine derivatives (amino sugars). This is achieved through an aqueous oxidation that catalyzed by Au nanoparticles dispersed on basic support under mild reaction conditions in water.

Green oxidation of 2-furaldehyde (furfural) and its homologues were investigated using solid acid catalyst and hydrogen peroxide (H 2 O 2 ) in aqueous media to form succinic acid (SA), a key chemical that affords wide applications in macromolecular, pharmaceutical and agrochemical industries. Amberlyst-15, a strongly acidic ion-exchange resin, functioned as an efficient solid acid catalyst for a highly selective SA production in the furfural oxidation reaction. The synthesized SA was simply isolated in high purity (supported by NMR spectral data). Furthermore, the utilization of Amberlyst-15 with H 2 O 2 was also useful in oxidizing carbonyl derivatives of furan (furfural, 5-hydroxymethyl-2-furaldehyde, furoic acid) to a one carbon less linear di-carboxylic acid such as SA and 2-oxoglutaric acid (OGA) under moderate conditions. This catalytic oxidation process with an acid catalyst and H 2 O 2 promises to be a viable route for SA syntheses since they have the advantages of easy handling and simple purification decreasing the cost for the production, as compared to the current state of art.

The PVP-protected bimetallic gold/palladium nanoclusters (Au_xPd_y-PVP NCs) were prepared onto the solid base hydrotalcite (HT) with various Au:Pd (x:y) molar ratios. Transmission electron microscopy showed narrow particle size distributions of Au_xPd_y-PVP NCs with a mean diameter in the range of 2.6-3.0 nm regardless of Pd contents. Aerobic oxidations of 1-phenylethanol over the Au_xPd_y-PVP/HT catalysts exhibited that their catalytic activities were significantly affected by the Pd contents. Correlations between charge transfer between Au and Pd and catalytic activity of the Au_xPd_y-PVP/HT catalyst were investigated with X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), Michaelis-Menten kinetic studies for alcohol oxidation, and other analytical techniques. The peaks of Au 4f in the XPS spectra were shifted to lower energy side with increase of Pd content, indicating the electron transfer from Pd to Au atoms according to Pauling's electronegativity protocol. The electron densities in Au 5d orbital in the Au_xPd_y-PVP/HT catalysts estimated by the Au L_3-XANES spectra correlated well with their catalytic activities. Moreover, the kinetic studies also proposed that the electron rich Au 5d states, resulted from the intermetallic electron transfer from Pd atoms, strongly contributed to the rate-determination step in the alcohol oxidation. It was concluded that the electronic negativity in the Au 5d states controlled by the Pd contents accelerated the rate-determination step in alcohol oxidation through highly active radical-like intermediates.

Hydrotalcite-supported platinum nanoparticles (Pt NPs/HT) prepared by the immobilization method with soluble starch as a reducing and a stabilizing agent were applied as catalysts for the selective oxidation of glycerol using atmospheric molecular oxygen as an oxidant in water. The Pt NPs/HT catalyst achieved a high selectivity (68%) toward glyceric acid (GA) in base-free aqueous solution. The catalyst was removed from the solution by simple filtration after the reaction and could be reused up to three times with a high selectivity (71% in third recycled).

Achievements in advanced materials science have required close cooperation with innovations in nanotechnology. First, in this Minireview, two impressive examples of close relationships between materials science and nanotechnology are introduced by using the histories on the Lycuurgus Cup and H2 storage/release phenomena in Pd crystals. In the main sections, the recent advanced approaches and the impressive scope of size- and shape-controlled precious monometallic nanoparticle catalysts and the recent advances in organic-stabilizer-mediated specific catalysis are introduced. Heterogeneous catalysis is susceptible to nanoscale surface functionality and morphology, therefore, significant research has been directed towards controlled nanostructured catalysis associated with new nanotechnology for synthesis and analysis techniques. These discussions are with a view for future innovations in catalysis combined with nanotechnology.

This manuscript reviews recent literatures on synthesis of furfurals (5-hydroxymethylfurfural, furfural, 5-methyl-2-furaldehyde) from various sugars (glucose, fructose, d-galactose, d-arabinose, xylose, l-rhamnose, lactose, cellobiose, sucrose) and furfural conversions into other carbonyl compounds (2,5-diformylfuran, 2,5-furandicarboxylic acid, levulinic acid, succinic acid) using catalytic methodology. Our recent achievements on one-pot synthesis of furfurals using solid acid and base catalysts and selective oxidations of furfurals using heterogeneous catalysts are also included.

Acidolysis polymerization has been used to prepare phenol-derived polymers such as liquid crystalline (LC) polymers, and is catalyzed by mildly-alkaline salts. The catalytic effects of hydrotalcites (HTs), which are natural alkalescent minerals with controllable basicity, are investigated on the acidolysis copolymerization of coumarates such as p-coumaric acid and caffeic acid. As a result, the LC copolymer prepared in the presence of HT with a Mg/Al ratio of 3 shows higher molecular weight values than copolymers prepared in the presence of any other alkalescent salts. On the other hand, the copolymers prepared in the presence of HTs show a clear LC state where the polymer chains are oriented on the surface of the glass fibers. The resin, which is oriented by glass fiber fillers aligning along its longitudinal axis and is annealed at 300 °C for 20 min, shows a softening temperature of 305 °C while keeping a high mechanical strength of 85 MPa and a high mechanical modulus over 1 GPa.

a b s t r a c t Mg-Al hydrotalcites (HTs) prepared with a co-precipitation method in the different conditions were examined for the selective synthesis of carbonates via transesterification of glycols including glycerol, propylene glycol and ethylene glycol. The prepared HT aged for 18 h exhibited a significant catalytic activity over the reaction. XRD and nitrogen adsorption measurements indicate the formation of the hydromagnesite (HM) possessing a high surface area after aging, however, the HM itself is inactive for the reaction. Additionally, progress of the reaction suggests the HT involving HM (HT-HM) shows a gradual increase of glycerol carbonate yield following large uptake of glycerol. The catalyst exhibited a significant catalytic activity in the reaction under the low concentration of glycerol. Therefore, we concluded that the HT-HM acts as a highly active solid base catalyst for the selective synthesis of carbonates via transes- terification since the coexistent HM increased the catalytic activity by increasing both surface area and adsorption sites for substrate during the reaction.

To compare the catalytic performances against daily start-up and shut-down (DSS) operations between co-precipitated (CP) and impregnated (IMP) Cu-Al-O_x catalysts for the water gas shift (WGS) reaction, in-situ X-ray adsorption fine structure (XAFS) measurements, temperature-programmed reduction (TPR) profiles, X-ray diffraction (XRD) patterns and high resolution transition electron microscopy with an energy dispersive X-ray spectroscopy (TEM-EDS) analysis were performed. In-situ XAFS studies clearly indicated that the Cu species were frequently oxidized and reduced during DSS operations with steam treatment (DSS-like operation). Basedon in-situ XAFS and H_2-TPR profiles, the highly active and stable CP-catalyst possessed more susceptible Cu particles to oxidation/reduction (described as redoxable below) than IMP-catalyst even after the DSS-like operations. Interestingly, the XRD and TEM-EDS analysis observed the small Cu particles which were covered with a card-house structure of the in-situ formed boehmite in the case of the CP-catalyst after the DSS-like operations. According to these results, we concluded that the superior durability of CP-catalyst against frequent redox changes was attributed to the nanoscale coordination with the in-situ formed boehmite structure which preserves the small-redoxable Cu particles.

Levulinic acid was obtained from fructose over solid acid catalysts under mild reaction conditions in water. The reaction was carried out at different temperatures and amounts of catalysts to find the best reaction conditions. Among tested heterogeneous catalysts, Amberlyst-15 gave the highest LA yield (52%) with the lowest HMF yield (below 3%) under optimum conditions. Levulinic acid was isolated from the mixture after reaction by rotary vacuum evaporator with 47% isolated yield. The recycling experiments showed that Amberlyst-15 exhibited good activity even after 5 runs, though the LA yield gradually decreased from 52 to 30%.

One-pot synthesis of furans from various saccharides such as arabinose, rhamnose, and lactose were performed over solid acid and base catalysts. The combination of Amberlyst-15 and hydrotalcite cat...

Charge transfer in heteromeric structures such as gold–silver core–shell (Au@Ag) nanoparticles (NPs) and gold–silver–gold double-shell (Au@Ag@Au) NPs was demonstrated using X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) techniques. XANES analyses confirmed that the d-orbital hole density of the Au atoms increases in the following order: Au foil ≅ Au NPs < Au@Ag NPs < Au@Ag@Au NPs. In conjunction with observed positive and negative shifts in the Au 4f and Ag 3d binding energies in XPS spectra of Au@Ag and Au@Ag@Au NPs, we conclude that d electrons are transferred from Au to Ag in the heteromeric NPs due to the charge compensation mechanism. By taking advantage of the charge transfer phenomenon, one can modify the electronic structure of heteromeric NPs with enhanced chemical stability and optical/electronic properties.

2,5-Diformylfuran (DFF) was selectively synthesized from 5-hydroxymethylfurfural using a hydrotalcite-supported ruthenium catalyst (Ru/HT) by oxidation with molecular oxygen under mild reaction conditions. A combination of hydrotalcite, Amberlyst-15, and Ru/HT catalysts successfully afforded direct synthesis of DFF from hexoses such as fructose and glucose via isomerization, dehydration, and successive selective oxidation in one pot. Stepwise addition of catalyst improved DFF yield up to 49% from fructose and 25% from glucose, respectively.