山田 泰弘

The aim of this work is to develop an effective catalyst for the conversion of butanediols, which is derivable from biomass, to valuable chemicals such as unsaturated alcohols. The dehydration of 1,4-, 1,3-, and 2,3-butanediol to form unsaturated alcohols such as 3-buten-1-ol, 2-buten-1-ol, and 3-buten-2-ol was studied in a vapor-phase flow reactor over sixteen rare earth zirconate catalysts at 325 °C. Rare earth zirconates with high crystallinity and high specific surface area were prepared in a hydrothermal treatment of co-precipitated hydroxide. Zirconates with heavy rare earth metals, especially Y2Zr2O7 with an oxygen-defected fluorite structure, showed high catalytic performance of selective dehydration of 1,4-butanediol to 3-buten-1-ol and also of 1,3-butanediol to form 3-buten-2-ol and 2-buten-1-ol, while the zirconate catalysts were less active in the dehydration of 2,3-butanediol. The calcination of Y2Zr2O7 significantly affected the catalytic activity of the dehydration of 1,4-butanediol: a calcination temperature of Y2Zr2O7 at 900 °C or higher was efficient for selective formation of unsaturated alcohols. Y2Zr2O7 with high crystallinity exhibits the highest productivity of 3-buten-1-ol from 1,4-butanediol at 325 °C.

Oxygen-containing carbon materials such as graphene oxide have been studied intensively for a decade because of the high oxygen content, which is beneficial to disperse carbon materials in solutions and to support either metals or metal oxides on carbon materials. However, various oxygen-containing functional groups exist on carbon materials and controlling the structures is almost impossible. In this work, phloroglucinol (PG), which has a symmetrical structure with three hydroxyl groups relative to six aromatic carbon atoms, was found to be the best precursor among PG, cyanuric acid, trimesic acid, and melamine because of the high yield (63 wt%) at 573 K even in an open system which is essential for mass production. The materials synthesized from PG also showed the high dispersibility and/or solubility in solvents (N-methyl-2-pyrrolidone andN,N-dimethylformamide) and the low temperature to form carbon materials (573 K), which can be explained from (002) and (10) in X-ray diffraction pattern. X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, carbon-13 nuclear magnetic resonance with the aid of calculation of both spectra and carbonization mechanisms revealed that the high solubility of carbonized PG originates from the presence of ether and cyclic ether, which were formed from dehydration of hydroxy groups, and also some remained hydroxyl groups in carbonized PG. Oxygen-containing groups in carbonized PG were effective as an antioxidant. In addition, the coating of carbonized PG on silica nanoparticles imparted conductivity and lubricity to silica nanoparticles. Graphic abstract

Determination of the number of bromo groups and brominated positions of edges on carbon materials is essential for selective functionalization because the brominated positions influence their electronic structures. However, the determination is challenging because the analysis of introduced bromo groups on carbon materials is conventionally limited to quantitative analysis by X-ray photoelectron spectroscopy. In this work, infrared spectra (IR) of brominated aromatic compounds were analyzed experimentally and theoretically using reference aromatic compounds to verify that the calculated peak positions can be used to estimate the experimental peak positions of brominated aromatic compounds. IR spectra of brominated graphene nanoribbons (GNRs) with zigzag, armchair, and other edges were simulated as one of the carbon materials with clear edge structures. Their characteristic peak positions and tendencies of shifts were explained from the point of view of Mulliken charge, C-H and C=C length, and orbital hybridization. As the number of Br on GNRs increased, the peak positions basically shifted further, indicating that the density of Br and introduced positions of Br can be estimated from IR spectra. The detailed assignments obtained in this work will lead to selective functionalization of carbon materials.

炭素材料には多種類の欠陥（活性点）が存在し，欠陥の種類や割合により炭素材料の性質は大きく異なる．しかし，炭素材料の構造制御は難易度が高く，構造解析や性能向上も容易ではない．そこで，種々の実測による分析に計算を組み合わせた我々の構造解析に関する取り組みを紹介する．

© 2019 Elsevier B.V. Global supply of 1,3-butadiene (abbreviated as BD) is faced with a problem such as variation in chemical feedstock in recent years. Many research efforts have been made to produce BD from some renewable resources to replace petroleum. Biomass-derived C4 alcohols such as 2,3-, 1,3-, and 1,4-butanediol (BDO) can be regarded as alternative resources to manufacture BD. Direct dehydration of BDOs into BD as well as two-step dehydration through the corresponding unsaturated alcohols such as 3-buten-2-ol, 2-buten-1-ol, and 3-buten-1-ol has been proposed as an alternative BD production process. 2,3-BDO and 1,4-BDO can be directly dehydrated to produce BD over Sc2O3 and Yb2O3, respectively, whereas stepwise dehydration is necessary for other BDOs. In the two-step dehydration, efficient production of unsaturated alcohols from BDOs is a key technology to form BD with high selectivity. CeO2 with a cubic fluorite phase is extremely effective for the conversion of 1,3-BDO to form 3-buten-2-ol and 2-buten-1-ol, while heavy rare earth oxides are effective for the dehydration of 1,4-BDO to produce 3-buten-1-ol. We reviewed the BD production from C4 alcohols through not only direct dehydration but also stepwise dehydration in addition to the BD production through dehydrogenation of butenes which could be produced from 1- and 2-butanol.

Vapor-phase hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) was investigated over Al2O3-supported bimetallic Cu-Co catalysts with different Cu/Co weight ratios under ambient H-2 pressure. The bimetallic Cu-Co/Al2O3 catalyst with a Cu/Co weight ratio of 8/12 exhibits an excellent catalytic activity and stability: it showed a high GVL productivity of 5.46 kg kg(cat.)(-1) h(-1) with a GVL selectivity higher than 99% at 250 degrees C for 24 h. In the characterization of the catalysts, powder X-ray diffraction suggests that bimetallic Cu-Co particles on the Cu-Co/Al2O3 catalysts are composed of an alloy.

© 2018 Vapor-phase aldol condensation of butanal to form 2-ethyl-2-hexenal was carried out over several oxide catalysts such as SiO2-Al2O3, Al2O3, ZrO2, and SiO2. Catalysts with moderate and strong acid sites such as Al2O3 and SiO2-Al2O3 were active for the reaction in the initial period, whereas they deactivated rapidly. In contrast, SiO2 with weak acidity showed a low but a stable catalytic activity for the formation of 2-ethyl-2-hexenal. Thermogravimetric analyses of the samples used after the reactions indicate that SiO2 has the smallest amount of carbonaceous species that contributed to its stable activity among the tested catalysts. SiO2 catalysts with different pore sizes and specific surface areas were examined: SiO2 with a mean pore diameter of 10 nm and a surface area of 295 m2 g−1 showed the best catalytic performance and gave a 2-ethyl-2-hexenal selectivity of 90% at a conversion of 48% at 240 °C. In the catalytic test using deuterated SiO2, which was prepared by contacting SiO2 with deuterated water before the reaction, it was confirmed by a mass spectrometer that the deuterium atom of SiOD was transferred to a 2-ethyl-2-hexenal molecule during the reaction. It is indicated that silanol groups on the SiO2 surface played a role as an active site.

© 2018 Elsevier Ltd Isotropic pitch-based carbon fiber has been utilized for various applications such as thermal insulation materials for high-temperature furnace and additives for slide member, but the structure of the carbon fiber is still under debate. This is because the precursor pitch contains various aromatic compounds in addition to the complicated oxidation and carbonization reaction during production process of carbon fiber. In this work, oxidation processes of model compounds of pitch such as pyrene (sp2C–H with zigzag-like edges), triphenylene (sp2C–H with armchair edges), fluorene (pentagon with sp3CH2), and 9-methylanthracene (hexagon with sp3CH3) were analyzed using mass spectrometry, elemental analysis, infrared (IR), Raman, and X-ray photoelectron spectroscopy (XPS) in addition to calculation such as molecular dynamic simulation with a reactive force field (ReaxFF) and simulation of IR, Raman, and XPS spectra (Gaussian09). Combination of calculations and experiments revealed that oxidation proceeded in the order of zigzag-like edges > sp3CH3 > sp2CH2 > armchair edges, and the quinone formed by oxidation worked as a precursor for a crosslinking reaction. It is expected that the results of this work, which revealed the origin of the crosslinking, could lead to improve properties as well as to estimate the detailed structures of isotropic pitch-based carbon fiber.

© 2019 Elsevier B.V. Vapor-phase catalytic dehydration of butanediols (BDOs) such as 1,3-, 1,4-, and 2,3-butanediol was investigated over yttria-stabilized tetragonal zirconia (YSZ) catalysts as well as monoclinic zirconia (MZ). BDOs were converted to unsaturated alcohols with some by-products over YSZ and MZ. YSZ is superior to MZ for these reactions in a view point of selective formation of unsaturated alcohols. Calcination temperature of YSZ significantly affected the products selectivity as well as the conversion of BDOs: high selectivity to unsaturated alcohols was obtained over the YSZ calcined at high temperatures over 800 °C. In the conversion of 1,4-butanediol at 325 °C, the highest 3-buten-1-ol selectivity of 75.3% was obtained over the YSZ calcined at 1050 °C, whereas 2,3-butanediol was less reactive than the other BDOs. In the dehydration of 1,3-butanediol at 325 °C, in particular, it was found that a YSZ catalyst with a Y2O3 content of 3.2 wt.% exhibited an excellent stable catalytic activity: the highest selectivity to unsaturated alcohols such as 2-buten-1-ol and 3-buten-2-ol over 98% was obtained at a conversion of 66%. Structures of active sites for the dehydration of 1,3-butanediol were discussed using a crystal model of tetragonal ZrO2 and a probable model structure of active site was proposed. The well-crystalized YSZ inevitably has oxygen defect sites on the most stable surface of tetragonal ZrO2 (101). The defect site, which exposes three cations such as Zr4+ and Y3+, is surrounded by six O2− anions. The selective dehydration of 1,3-butanediol to produce 3-buten-2-ol over the YSZ could be explained by tridentate interactions followed by sequential dehydration: the position-2 hydrogen is firstly abstracted by a basic O2− anion and then the position-1 hydroxyl group is subsequently or simultaneously abstracted by an acidic Y3+ cation. Another OH group at position 3 plays an important role of anchoring 1,3-butanediol to the catalyst surface. Thus, the selective dehydration of 1,3-butanediol could proceed via the speculative base-acid-concerted mechanism.

© 2019 Elsevier B.V. Vapor-phase isomerization of 3-pentenal to 2-pentenal was performed over various oxide catalysts. An amorphous SiO2 catalyst with a weak acidity and medium mesopore size showed a conversion over 82% with 2-pentenal selectivity higher than 95% at 250 °C. Several characterizations, such as thermogravimetric analysis, diffuse reflectance infrared Fourier-transform, temperature-programmed desorption of adsorbed NH3, and isotope experiment using deuterated SiO2, were performed to investigate the active sites on SiO2. A SiO2 with a specific pore size showed a stable catalytic activity after a rapid decrease at the initial stage of the reaction. The isomerization of 3-pentenal to 2-pentenal was found to be an equilibrium reaction: the pressure equilibrium constant was estimated to be ca. 5 at 250 °C. The weak acidic silanol groups on SiO2 were proved to be the active sites for the isomerization of 3-pentenal to 2-pentenal. A possible reaction mechanism was proposed: hydrogen of the silanol groups on SiO2 was coordinated to 2-pentenal with a form of six-membered ring, which can explain the primary product of cis isomer.

Vapor-phase dehydrogenation of 1-decanol to form decanal was performed over various supported Cu catalysts such as Cu/SiO2, Cu/ZnO, and Cu/Al2O3. Among the catalysts tested in this work, Cu/SiO2 showed a high and stable catalytic activity for the conversion of 1-decanol to form decanal, and 77.4% conversion of 1-decanol with 98.4% selectivity to decanal was achieved over Cu/SiO2 catalyst in NZ flow at 275 degrees C. The physical properties of SiO2 support affected the catalytic activity, and the SiO2 with a surface area of 451 m(2) g(-1) and an averaged pore size of 6 nm was preferable for the formation of decanal. The catalytic reaction was regulated by equilibrium: the pressure equilibrium constant, K-p, was estimated to be 0.30 atm at 275 degrees C. The deactivation of the catalyst was observed in N-2 flow at 325 degrees C, while it was not observed in H-2. The activity of the deactivated catalyst was completely recovered in N-2 at 275 degrees C after calcination in air at 400 degrees C followed by H-2 reduction. Based on the DRIFT and TG analyses, hydrocarbon species were accumulated on the catalyst surface in the initial period of the reaction. In addition, it was found that the dehydrogenation of the hydrocarbon species accumulated on the catalyst mainly caused the catalytic deactivation.

© 2019 Elsevier B.V. Vapor-phase dehydration of 1,3-butanediol was performed over Yb2O3-ZrO2 catalysts in an ambient nitrogen atmosphere. Catalysts were prepared by a hydrothermal (HT) method as well as a coprecipitation method. The Yb2O3-ZrO2 sample prepared by HT was confirmed to be crystallites of oxygen-defected type cubic Yb2Zr2O7, while the as-prepared coprecipitation sample was amorphous. The HT samples had high specific surface areas as ca. 40 m2 g−1 even after calcined at temperatures higher than 800 °C, whereas the coprecipitation samples without HT was readily sintered at the high temperatures. The best catalytic performance was obtained over HT Yb2O3-ZrO2 catalyst calcined at 900 °C: the total selectivity to unsaturated alcohols was higher than 95% at a 1,3-butanediol conversion of 82% at 325 °C. The structure of active sites and the reaction mechanism of the dehydration of 1,3-butanediol were discussed. We proposed that an oxygen defect site on the stable (111) face of cubic Yb2Zr2O7 would provide an active site, and that Zr4+, Yb3+, and O2- exposed on the defect could coordinate with a 1,3-butanediol molecule to form a tridentate coordination structure, which possibly initiate the dehydration to produce unsaturated alcohols through a base-acid concerted mechanism.

Graphene nanoribbons (GNRs) have recently emerged as alternative 2D semiconductors owing to their fascinating electronic properties that include tunable band gaps and high charge-carrier mobilities. Identifying the atomic-scale edge structures of GNRs through structural investigations is very important to fully understand the electronic properties of these materials. Herein, we report an atomic-scale analysis of GNRs using simulated X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Tetracene with zigzag edges and chrysene with armchair edges were selected as initial model structures, and their XPS and Raman spectra were analyzed. Structurally expanded nanoribbons based on tetracene and chrysene, in which zigzag and armchair edges were combined in various ratios, were then simulated. The edge structures of chain-shaped nanoribbons composed only of either zigzag edges or armchair edges were distinguishable by XPS and Raman spectroscopy, depending on the edge type. It was also possible to distinguish planar nanoribbons consisting of both zigzag and armchair edges with zigzag/armchair ratios of 4:1 or 1:4, indicating that it is possible to analyze normally synthesized GNRs because their zigzag to armchair edge ratios are usually greater than 4 or less than 0.25. Our study on the precise identification of GNR edge structures by XPS and Raman spectroscopy provides the groundwork for the analysis of GNRs.

Carbon materials such as graphene and graphene nanoribbon with zigzag and armchair edges have attracted much attention because of various applications such as electronics, batteries, adsorbents, and catalyst supports. Preparation of carbon materials with different edge structures at a large scale is essential for the future of carbon materials, but it is generally difficult and expensive because of the necessity of organic synthesis on metal substrates. This work demonstrated a simple preparation method of carbon materials with zigzag and armchair edges with/without nonmetallic silica supports from aromatic compounds such as tetracene with zigzag edges and chrysene with armchair edges and also determined the edge structures in detail by three types of analyses such as (1) reactive molecular dynamic simulation with a reactive force field, (2) Raman and infrared (IR) spectra combined with calculation of spectra, and (3) reactivity analyzed by oxidative gasification using thermogravimetric analysis. Two different types of carbon materials with characteristic Raman and IR spectra could be prepared. These carbon materials with different edge structures also clearly showed different tendency in oxidative gasification. This work did not only show the simple preparation method of carbon materials with different edge structures, but also contributes to the development of detailed analyses for carbon materials.

© 2018 American Chemical Society. CO2 removal and sensing, especially by amine groups, are necessary to prevent global warming. However, understanding the dynamic mechanism of CO2 capture on nitrogen sites remains challenging. We fabricated a nitrogen-doped polymer and compared the mechanism of CO2 adsorption with that of a similar polymer without nitrogen atoms by evaluating the CO2 adsorption at 243, 273, and 303 K; electrical resistance changes due to CO2 adsorption at 297 K; and molecular dynamics simulations. The CO2 adsorption of the nitrogen-doped polymer was significantly improved owing to the negative partial charges on nitrogen sites. In addition, the electrical response of the nitrogen-doped polymer to CO2 showed adequate reversibility. These results originated from the stronger adsorption of CO2 on nitrogen sites than on ring and vinyl sites. Our findings contribute to the understanding of CO2-nitrogen attraction and will be beneficial for the development of efficient CO2 capture and sensing.

Edge structures of carbon materials such as zigzag and armchair edges are known to affect their chemical and electronic properties. Although infrared spectroscopy (IR) has been known to be capable of identifying such edge structures, quantitative analysis using IR spectra has been conducted using only out-of-plane sp(2)C-H bending vibration, and the estimation of the percentage of edges is still challenging. In this work, a novel two-dimensional method to quantify edge structures of carbon materials with and without pentagons was developed by analyzing both out-of-plane sp(2)C-H bending and in-plane sp(2)C-H stretching vibration. Calibration factors of sp(2)C-H on each type of edge were obtained from experimental and simulated IR spectra of various reference compounds. Using the calibration factors, the edge structures of carbonized aromatic compounds with zigzag edges such as tetracene, armchair edges such as chrysene, and zigzag-like edges such as coronene were estimated quantitatively. From tetracene carbonized at 893 K, chrysene carbonized at 933 K, and coronene carbonized at 873 K, carbon materials with 20% of zigzag edges, 38% of armchair edges, and 67% of others edges were prepared, respectively. This method can be utilized as a quantitative analysis to determine edge structures of various carbon materials prepared below 933 K at the lowest.

Cu-Ni/SiO2 catalyst was developed by impregnation assisted with citric acid for the vapor-phase hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL). The prepared catalysts were characterized by using X-ray powder diffraction (XRD), transmission electron microscope (TEM), temperature-programed reduction, thermogravimetry analysis, and X-ray fluorescence analysis. The XRD analysis and the TEM observation of the catalyst samples indicate that the usage of citric acid in the preparation process of impregnation improved the dispersion of Cu and Ni metal on SiO2. A Cu-Ni/SiO2 catalyst with Cu loading of 4 wt.% and Ni of 16 wt.% showed the best performance in the hydrogenation of LA to GVL under ambient H-2 pressure at a high weight hourly space velocity (WHSV) of 13.2 h(-1) and 250 degrees C: the conversion was 98.2% and the GVL selectivity was 97.6%. The catalyst prepared by citric acid-assisted impregnation showed the resistance to catalyst deactivation.

Vapor-phase dehydration of 1,4-butanediol and 3-buten-1-ol to produce 1,3-butadiene was investigated over rare earth oxides such as Lu2O3, Yb2O3, Tm2O3, Er2O3, and Sc1.0Yb1.0O3. In the dehydration of 3-buten-1-ol, heavy rare earth oxides such as Lu2O3, Yb2O3, and Er2O3 showed high catalytic performance for the selective formation of 1,3-butadiene with producing small amount of propylene whereas acidic catalysts such as alumina decomposed 3-buten-1-ol into propylene. In particular, over Yb2O3 calcined at 800 degrees C, 3-buten-1-ol was converted with a yield of 1,3-butadiene higher than 95% at 340 degrees C. In the dehydration of 1,4-butanediol, furthermore, we developed an efficient catalytic system: 1,3-butadiene was produced via an intermediate, 3-buten-1-ol, over Yb2O3 with an excellent yield of 96% at 360 degrees C and a high contact time of 2.26 h. Yb2O3 successfully inhibited the major side reaction such as decomposition of 3-buten-1-ol to propylene and provided the selective production of 1,3-butadiene from 1,4-butanediol.

Vapor phase dehydration of 5-amino-1-pentanol to produce piperidine was investigated over various oxide catalysts such as ZrO2, TiO2, Al2O3 and SiO2. Among the tested catalysts, SiO2 selectively produced piperidine at 300 degrees C. A high 5-amino-1-pentanol conversion of 99.9% with a piperidine selectivity of 94.8% was achieved over weak acidic SiO2. In an experiment using isotope such as deuterated water, surface hydroxy groups of SiO2 are concluded to be the active centers.

Edges of carbon materials have been known to work as active sites for various applications such as catalysts, adsorbent, and electrodes, but selecting precursors for carbon materials with controlled edges in the absence of metallic substrate is challenging. This work developed a method to select the superior precursors instantaneously using molecular dynamic simulation. This simulation predicted that hydrogen in precursors gasified and the hydrogen attacked the active sites in precursors upon carbonization, causing the decrement of active sites. Thus, it is essential to reduce the concentration of hydrogen in precursors and it is also necessary to introduce reactive functional groups near the active site to protect the active sites. We indeed synthesized the selected precursors such as diethynyl anthracene, diethynyl chrysene, divinyl naphthyridine, and divinyl phenanthroline and proved that edges in those precursors were maintained even after carbonization at 773 K using diffuse reflectance infrared Fourier transform and X-ray photoelectron spectroscopy with the aid of spectra simulated by density functional theory calculation. Especially, ca. 100% of edge structures of zigzag edges and armchair edges in diethynyl anthracene and diethynyl chrysene was maintained even after carbonization at 773 K. (C) 2017 Elsevier Ltd. All rights reserved.

© 2017 Elsevier B.V. Vapor-phase catalytic dehydration of 1,5-pentanediol (1,5-PDO) was investigated over monoclinic ZrO2 catalysts modified with basic oxides. An unsaturated alcohol, 4-penten-1-ol (4P1OL), was produced together with the formation of tetrahydropyran, δ-valerolactone, 1,4-pentadiene, pentanal, 1-pentanol, and 5-hydroxypentanal, etc. Among the modified ZrO2 catalysts, only ZrO2 modified with MgO enhanced the selectivity to 4P1OL efficiently. The most active modified catalyst was found to have 20 mol% MgO and a calcination at 800 °C (MgO/ZrO2), and the selectivity of 4P1OL exceeded 83% at 400 °C. A pulse adsorption measurement of several chemicals clarified adsorptive interaction between a reactant and a catalyst at 220 °C: the interaction between 1,5-PDO and MgO/ZrO2 was stronger than the other adsorbates and catalysts. Another strong adsorptive interaction between 1,4-butanediol and CaO/ZrO2, which was effective in the dehydration of 1,4-butanediol to produce 3-buten-1-ol, was also observed.

Vapor-phase hydrogenation of levulinic acid (LA) and methyl levulinate (ML) to gamma-valerolactone (GVL) was performed over non-noble metal-based catalysts such as Cu/Al2O3, Ni/SiO2 and Co/SiO2. The catalytic activity and stability of the Cu-, Ni- and Co-based catalysts for the formation of GVL from ML and LA were investigated and compared at a low contact time of 0.3 h. In the hydrogenation of ML to GVL, the order of the catalytic activity for the conversion of ML was Cu/Al2O3 > Co/SiO2 > Ni/SiO2. Cu/Al2O3 was the most selective for the formation of GVL, whereas it was unstable in contrast to the other catalysts. In the hydrogenation of LA to GVL, the order of the catalytic activity for the conversion of LA was Ni/SiO2 > Cu/Al2O3 > Co/SiO2, which is the same as the order of the catalyst stability, while Cu/Al2O3 was the most selective for the formation of GVL from LA. The reactions were also performed in N-2 atmosphere in order to study the reaction pathways. Methyl 4-hydroxypentanoate was supposed to be the intermediate in the hydrogenation of ML to GVL, whereas the reaction pathways in the hydrogenation of LA to GVL were dependent on the catalyst species. Based on the TG analysis of the used catalysts, it was found that LA led to more severe catalyst deactivation than ML did. (C) 2017 Elsevier B.V. All rights reserved.

Vapor-phase hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) was performed over SiO2-supported Cu-Ni bimetallic catalysts with different Cu/Ni weight ratios under ambient H-2 pressure. Characterization of the catalysts was carried out using powder X-ray diffraction, temperature-programmed reduction and thermogravimetric analysis. In contrast to the monometallic catalysts i.e. Ni/SiO2 and Cu/SiO2, the Cu-Ni/SiO2 bimetallic catalyst with a Cu/Ni weight ratio of 6/14 exhibits an excellent catalytic activity, and gave a GVL yield higher than 99% with a productivity of 1.64 kg(GvL) kg(cat.)(-1)h(-1) at 250 degrees C and at a high WHSV of 1.65 h(-1) for 50 h.

Hydrogenation of gamma-valerolactone to 1,4-pentanediol was performed over both precious and base metal catalysts in a continuous flow reactor under H-2 pressure. Cu/ZnO catalyst showed the highest catalytic performance for the formation of 1,4-pentanediol from gamma-valerolactone. Low reaction temperatures such as 140 degrees C were preferable for achieving 1,4-pentanediol, and high temperatures led to the further conversion of 1,4-pentanediol to 2-methyltetrahydrofuran and 1-pentanol. High H-2 pressures and moderate H-2 flow rates such as 90 cm(3) min(-1) were effective for the formation of 1,4-pentanediol. Calcination temperature of Cu/ZnO significantly affected its catalytic activity. A Cu/ZnO catalyst with a Cu metal loading of 40 wt.% gave the gamma-valerolactone conversion of 82.3% with the 1,4-pentanediol selectivity of 99.2% at 140 degrees C under 1.5 MPa of H-2 pressure, while no decrease in the catalytic activity was observed for 10 h.

Despite recent advances in the carbonization of organic crystalline solids like metal-organic frameworks or supramolecular frameworks, it has been challenging to convert crystalline organic solids into ordered carbonaceous frameworks. Herein, we report a route to attaining such ordered frameworks via the carbonization of an organic crystal of a Ni-containing cyclic porphyrin dimer (Ni-2-CPDPy). This dimer comprises two Ni-porphyrins linked by two butadiyne (diacetylene) moieties through phenyl groups. The Ni-2-CPDPy crystal is thermally converted into a crystalline covalent-organic framework at 581 K and is further converted into ordered carbonaceous frameworks equipped with electrical conductivity by subsequent carbonization at 873-1073 K. In addition, the porphyrin's Ni-N-4 unit is also well retained and embedded in the final framework. The resulting ordered carbonaceous frameworks exhibit an intermediate structure, between organic-based frameworks and carbon materials, with advantageous electrocatalysis. This principle enables the chemical molecular-level structural design of three-dimensional carbonaceous frameworks.

Vapor-phase dehydration of C4 unsaturated alcohols such as 3-buten-l-ol, 2-buten-1-ol and 3-buten-2-ol were performed to produce 1,3-butadiene over various solid catalysts including ordinary solid acid catalysts such as Al2O3, SiO2-Al2O3, and TiO2 and basic rare earth metal oxides such as Yb2O3 and CeO2. In the reaction of 3-buten-1-ol, 1,3-butadiene could not be selectively produced because the acid catalysts decomposed 3-buten-1-ol into propylene. In contrast to the acid catalysts, CeO2 inhibited the decomposition of 3-buten-1-ol and showed a relatively high performance for the formation of 1,3-butadiene. In the dehydration of 2-buten-1-ol and 3-buten-2-ol, however, acid catalysts were effective for the formation of 1,3-butadiene. Among the tested catalysts, commercial SiO2-Al2O3 showed a relatively high catalytic performance, although it deactivated rapidly. We prepared a series of SiO2/Al2O3 catalysts by depositing SiO2 species onto Al2O3 support, and the SiO2/Al2O3 with a SiO2 content of 10 wt.% showed more stable catalytic activity than the commercial SiO2-Al2O3. Furthermore, modification of SiO2/Al2O3 with Ag at a loading of 3-5 wt.% was found to be efficient for inhibiting the coke formation and improving the catalytic stability of SiO2/Al2O3 in the dehydration of both 2-buten-1-ol and 3-buten-2-ol under hydrogen flow conditions. (C) 2016 Elsevier B.V. All rights reserved.

© 2016 Elsevier B.V. Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) to produce 3-buten-2-ol (3B2OL) was investigated over several monoclinic ZrO2 (m-ZrO2) catalysts modified with alkaline earth metal oxides (MOs), such as SrO, BaO, and MgO, to compare with the previously reported CaO/m-ZrO2. It was found that these modifiers enhanced the 3B2OL formation to the same level as CaO did by loading an appropriate MO content. Among all the tested catalysts, the BaO/m-ZrO2 calcined at 800 °C with a low BaO content (molar ratio of BaO/ZrO2 = 0.0452) shows the highest 2,3-BDO conversion (72.4%) and 3B2OL selectivity (74.4%) in the initial stage of 5 h at 350 °C. In order to characterize those catalysts, their catalytic activities, crystal structures, and basic properties were studied in detail. In X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) experiment, it was elucidated that highly dispersed M-O-Zr (M = Ca, Sr, and Ba) hetero-linkages were formed on the surface by loading these MOs onto m-ZrO2 with an appropriate content and then calcining at 800 °C. It can be concluded that the M-O-Zr hetero-linkages generate the proper base-acid balance for the efficient formation of 3B2OL from 2,3-BDO.

Carbon nanomaterials assembled into micrometer-scale configurations are highly useful because of their unique molecular transport and adsorption properties, improved operability, and versatility in industrial/research applications. Here we propose a facile approach to assemble carbon nanotubes (CNTs) into monodisperse microparticles through rapid condensation and accumulation of CNTs in aqueous droplets in a non-equilibrium state. The droplets were generated by means of a microfluidic process or membrane emulsification, using a water-soluble polar organic solvent as the continuous phase. Because water molecules in the droplets were rapidly dissolved into the continuous phase, the CNTs were dramatically condensed and stable microparticles were finally formed. We prepared microparticles using both multi-walled and single-walled CNTs, and the size was controllable in the range of 10-40 mm simply by changing the initial CNT concentration. Interestingly, the morphologies of the particles were not spherical in many cases, and they were controllable by changing the type of the organic solvent and/or using additives in the dispersed phase. Physicochemical characterization suggested good compatibility of the CNT microparticles when used as supports for catalysts, adsorbents, and electrodes.

© 2017 Elsevier B.V. Vapor-phase catalytic dehydration of 1,4-butanediol (1,4-BDO) was investigated over modified ZrO2catalysts. In the dehydration of 1,4-BDO over monoclinic ZrO2(m-ZrO2), an unsaturated alcohol, 3-buten-1-ol (3B1OL), was produced together with tetrahydrofuranand γ-butyrolactone. Among alkaline earth metal oxide modifiers, CaO with an appropriate content significantly enhanced the 3B1OL selectivity of m-ZrO2. The modification of CaO was more efficient over m-ZrO2than tetragonal ZrO2. CO2-TPD measurements reveal that CaO supported on m-ZrO2calcined at 800 °C or higher generated new basic sites, which are attributed from Ca-O-Zr hetero-linkages, for the effective formation of 3B1OL from 1,4-BDO. In order to create more Ca-O-Zr hetero-linkages on the m-ZrO2surface efficiently, additional ZrO2was loaded on m-ZrO2together with CaO via a co-impregnation method. At an appropriate weight ratio of CaO/ZrO2 = 7/2 loaded on m-ZrO2, both the 1,4-BDO conversion and the 3B1OL selectivity were enhanced greatly. Especially, the 3B1OL selectivity exceeded 90% at 350 °C.

© 2017 Elsevier B.V. Vapor-phase intramolecular aldol condensation of 2,5-hexanedione to produce 3-methylcyclopent-2-enone was performed over several ZrO2-supported alkali and alkali earth metal oxides. Among the tested catalysts, ZrO2-supported Li2O showed a stable catalytic activity. A high 2,5-hexanedione conversion of 99% with a 3-methylcyclopent-2-enone selectivity of 96% was achieved over a 20 mol% Li2O-loaded ZrO2catalyst at 250 °C.

© The Royal Society of Chemistry 2017. Production of fuels and chemicals from renewable biomass resources is an attractive way to alleviate the shortage of fossil fuels and reduce CO2 emission. Glycerol is an important biomass derivative currently produced as a by-product in the manufacture of biodiesel in a huge amount close to 10 wt% of the overall biodiesel production. The application of glycerol as a renewable raw material has attracted much attention in the last decade, and some catalytic technologies for the conversion of glycerol into useful chemicals such as methanol, epichlorohydrin, and 1,2-propanediol have been established. Acrylic acid is an important bulk chemical widely used in the manufacture of polymeric products and is currently produced in the petrochemical industry via two-step gas-phase oxidation of propylene. The depletion of fossil resources motivates developments in the production of acrylic acid from renewable raw materials. Glycerol has potential for use as a raw material for the production of acrylic acid, and the variety of glycerol derivatives provides opportunities for producing acrylic acid from glycerol through different ways. In this review, possible routes and the corresponding catalytic technologies for the conversion of glycerol to acrylic acid are primarily summarized, and the advantages as well as the challenges in each route are discussed.

© 2017 Elsevier B.V. Vapor-phase catalytic production of 2,3-butanediol from acetoin and diacetyl was investigated over the supported metal catalysts such as Ni, Co, Cu, and Ag. A yield of 2,3-butanediol higher than 90% can be obtained from both acetoin and diacetyl over Ni/SiO2 catalyst in an H2 flow at 150 °C. Since the hydrogenation is an exothermic reaction, a low temperature is favorable to gain a full production of 2,3-butanediol. It was found that the equilibrium among 2,3-butanediol, acetoin, and diacetyl could be achieved at a contact time of the reactants with catalyst longer than 1.67 h. The pressure equilibrium constants in the hydrogenation were calculated by the outlet gas composition.

Nitrogen-doped carbon materials such as graphene and activated carbon have been studied as solid base catalysts. However, active sites of carbon catalysts have long been ambiguous because of the presence of various functional groups. This work clarified the dependence of positions of nitrogen atoms in aromatic hydrocarbons on catalytic activities of well-known Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate to produce ethyl cyanocinnamate (ECC) as one of the examples for catalytic reactions. Catalytic activities of 30 kinds of aromatic hydrocarbons composed of one, two, and three aromatic rings with zero, one, two, and three nitrogen atoms were compared. Phenazine with zigzag edges and pyridinium ion with quaternary nitrogen showed low catalytic activities. On the other hand, 1,10-phenanthroline with armchair edges showed a high ECC selectivity of 99.3% and a high ECC yield of 59.0%. Among various aromatic hydrocarbons carbonized on silica, 1,10-phenanthroline carbonized at 923 K exhibited the highest ECC selectivity of 89.5% and the highest ECC yield of 10.2% because of the highest percentage of 1,10-phenanthroline-like N after carbonization. We believe that this work can serve as a perfect example to examine the performance of carbon catalysts at a molecular level in the future. (C) 2016 Elsevier Ltd. All rights reserved.

Selective doping of nitrogen into carbon materials in the absence of catalysts is a key for various applications of carbon materials. It is well known that most nitrogen-containing raw materials generate unnecessary functional groups during carbonization. Many researchers have noticed the significance of the selective nitrogen doping, whereas only a few works have reported the selective doping. In addition, those few works used catalysts to synthesize nitrogen-doped carbon materials, but the presence of catalysts limits the applications of nitrogen-doped carbon materials. This study found an unusual aromatic compound, imidazo[1,2-a]pyridine (IP), which maintained 88 % of the functional groups of as-received IP even after carbonization at 673 K in the absence of catalysts, and the functional groups were further maintained up to 773 K. The percentage of remaining functional groups was revealed using our state-of-the-art techniques of simulated X-ray photoelectron spectroscopy and Raman spectroscopy combined with transition state calculation using density functional theory. The low carbonization temperature as well as selective doping of nitrogen was achieved because of the low activation energy of dehydrogenation reaction among IP molecules compared to the high activation energy of radical formation for scission of C-N bonding.

© 2016 Elsevier B.V. Vapor-phase dehydration of several 1,2-alkanediols, such as 1,2-ethanediol, 1,2-propanediol, 1,2-butanediol and 1,2-pentanediol, to produce corresponding aldehydes was investigated over silica-supported WO3 catalyst, which was prepared by impregnation method and then calcined at 320 °C. Higher than 90% yield of aldehydes could be achieved over WO3/SiO2 catalyst at 250 °C with a feed of 20% aqueous 1,2-alkanediol solution. Both Brønsted and Lewis acid sites exist on WO3/SiO2 catalyst, while Brønsted acid sites are proposed to be the active species for the formation of aldehyde. High concentrations of H2O were effective for inhibiting the intermolecular reaction and improving the selectivity to aldehydes. The dehydration of different 1,2-alkanediols was compared under different reaction conditions. The reactivity of 1,2-ethanediol was low and the product distribution was several comparing with those of the other 1,2-alkanediols. Cyclic acetal, which was generated by the cyclodehydration of the produced aldehyde with another 1,2-alkanediol, was a main by-product, and the formation of acetal was affected by both the temperature and the carbon-chain length of the 1,2-alkanediols.

© 2016 Elsevier B.V. Vapor-phase lactonization of levulinic acid to produce angelica lactones, which include α-, β- and γ-form isomers, was performed in fixed-bed down-flow glass reactors over various oxide catalysts. SiO2 and SiO2-Al2O3 showed relatively high catalytic activity. The lactonization of levulinic acid to angelica lactones was found to be an endothermic equilibrium reaction, and the pressure equilibrium constant was calculated to be 0.2 atm at 275 °C. High temperatures and reduced pressures were effective for shifting the equilibrium from levulinic acid to angelica lactones, while the suitable reaction temperature was estimated to be 275 °C because temperatures higher than 275 °C decreased the selectivity to angelica lactones. The highest angelica lactones yield of 87.5% was achieved at a levulinic acid conversion of 95.3% over SiO2 under reduced pressure conditions of ca. 5 kPa at 275 °C. IR, NH3-TPD and TG analyses were performed for characterizing the catalysts used after the reactions together with a silylated SiO2 prepared for studying the active species on SiO2. The silanol groups of SiO2 with weak acidity were proposed to be the active species.

© 2016 Elsevier B.V. Applications of renewable biomass provide facile routes to alleviate the shortage of fossil fuels as well as to reduce the emission of CO2. Glycerol, which is currently produced as a waste in the biodiesel production, is one of the most attractive biomass resources. In the past decade, the conversion of glycerol into useful chemicals has attracted much attention, and glycerol is mainly converted by steam reforming, hydrogenolysis, oxidation, dehydration, esterification, carboxylation, acetalization, and chlorination. In this review, we focused on the catalytic hydrogenolysis of glycerol into C3 chemicals, which contain many industrially important products such as 1,2-propanediol, 1,3-propanediol, allyl alcohol, 1-propanol and propylene. In the hydrogenolysis of glycerol into propanediols, advantages and disadvantages of liquid- and vapor-phase reactions are compared. In addition, recent studies on catalysts, reaction conditions, and proposed pathways are primarily summarized and discussed. Furthermore, new research trends are introduced in connection with the hydrogenolysis of glycerol into allyl alcohol, propanols and propylene.

© 2016 Elsevier B.V. All rights reserved. Vapor-phase self-aldol condensation of butanal was performed over various solid catalysts. Among the tested catalysts, SiO2-Al2O3, Nb2O5 and TiO2 showed relatively high catalytic activity for the formation of aldol condensation product, 2-ethyl-2-hexenal, whereas all the catalysts deactivated rapidly. In order to stabilize the catalytic activity, metal-modified catalysts were investigated in hydrogen flow, and it was found that Ag-modified TiO2 showed the best catalytic performance. Characterizations such as XRD, TPD, TPR, TG-DTA, and DRIFT were performed for investigating the effect of the additive Ag and analyzing the coke component. The loaded Ag metal inhibited the formation of carbon accumulated on catalyst surface, and H2 carrier gas was indispensable in the inhibition. Ag would work as a remover of the products on the catalyst surface together with H2 to prevent dehydrogenation followed by coke formation. Self-aldol condensation of butanal was stabilized over Ag-modified TiO2 at Ag2O loadings higher than 3 wt.% at 220 °C in H2 flow. TiO2 with Ag2O of 5 wt.% showed the best catalytic performance and gave a 72.2% selectivity to 2-ethyl-2-hexenal at 72.1% conversion in H2 flow at 220 °C.

X-ray photoelectron spectroscopy (XPS) is among the most powerful techniques to analyze defective structures of carbon materials such as grapheme and activated carbon. However, reported assignments of defects, especially sp(3)C and sp(2)C, are questionable. Most reports assign sp(3)C peaks to be higher than sp(2)C peaks, whereas a few reports assign sp(3)C peaks to be lower than sp(2)C peaks. Our group previously reported that calculated binding energies of sp(3)C were basically lower than those of sp(2)C. This work clarified that one of the reasons for the prevailing ambiguous assignments of sp(3)C peaks is charging effects of diamond.

© 2016 Elsevier B.V. Vapor-phase catalytic dehydration of 5-amino-1-pentanol was investigated over various oxide catalysts including rare earth oxides (REOs). Over ordinary acidic oxides such as Al2O3, SiO2, SiO2-Al2O3, TiO2, and ZrO2, a cyclic amine such as piperidine was mainly produced at temperatures of 300 °C and higher. In contrast, basic REOs with a cubic bixbyite structure showed the catalytic activity in the conversion of 5-amino-1-pentanol to produce 4-penten-1-amine at 425 °C. In REO catalysts, Tm2O3, Yb2O3, and Lu2O3 showed the high conversion of 5-amino-1-pentanol and the high selectivity to 4-penten-1-amine. Especially, Yb2O3 calcined at 800 °C showed a high formation rate of 4-penten-1-amine with the selectivity of ca. 90% at 425 °C. In comparing the reactivity of several amino alcohols to form the corresponding unsaturated amines, Yb2O3 effectively catalyzed the dehydration of 6-amino-1-hexanol into 5-hexen-1-amine, whereas 3-amino-1-propanol and 4-amino-1-butanol were not effectively dehydrated due to the decomposition of the reactant.

© 2016 The Royal Society of Chemistry. A vapor-phase dehydration of acetaldoxime to acetonitrile was investigated over various solid catalysts. Among the tested catalysts, ZrO2, Al2O3 and SiO2 showed high catalytic activity for the formation of acetonitrile from acetaldoxime, while the correlation between catalytic activity and the acid property of the catalysts was not observed. Weak acidic sites such as silanols sufficiently work as catalytic sites for the dehydration, which does not require strong acids such as zeolites. Several SiO2 catalysts with different physical properties were tested, and the SiO2 with the smallest pore size and the highest specific surface area showed the highest catalytic activity for the formation of acetonitrile. Because the dehydration of acetaldoxime to acetonitrile is exothermic, a large amount of reaction heat was generated during the reaction, and the reaction temperature was found to be significantly affected by the feed rate of the reactant andthe absence of the external heat, and the acetonitrile yield higher than 90% could be achieved in such a green operation under the environment-friendly adiabatic conditions ce of the external heat, and the acetonitrile yield higher than 90% could be achieved in such a green operation under the environment-friendly adiabatic conditions.

© 2016 The Chemical Society of Japan. Global supply of 1,3-butadiene (abbreviated as BD) is faced with problems such as unstable price of petrochemicals and variation of chemical feedstock in recent years. Many research works have been conducted to produce BD from some renewable resources instead of petroleum. Among them, biomass-derived C4 alcohols such as 1,3-butanediol (1,3-BDO), 2,3-butanediol (2,3-BDO), and 1,4-butanediol (1,4-BDO) have been considered as alternative resources to produce BD. Direct dehydration of butanediols (BDOs) into BD, however, needs high reaction temperatures while the dehydration into their corresponding unsaturated alcohols (UOLs) such as 3-buten-2-ol (3B2OL), 2-buten-1-ol (2B1OL), and 3-buten-1-ol (3B1OL) proceeds at rather low temperatures over specific catalysts. The latter step of BDO dehydration, dehydration of UOLs to BD, is readily catalyzed by solid acids even at lower temperatures than those at which BDOs are dehydrated completely. Thus, efficient formation of UOLs from BDOs would be a key process to produce BD with high selectivity. We summarize the BD production from C4 alcohols as well as the dehydration of BDOs to UOLs, in addition to the BD production via ethanol dimerization.

C1s X-ray photoelectron spectroscopy (XPS) spectra of graphene with two to eight pentagons and fullerene pentagons were simulated using density functional theory calculation. Peak shifts and full width at half maximum (FWHM) of calculated C1s spectra were compared with those of actual C1s spectra. Introduction of up to four isolated pentagons had no influence on shifts of the calculated peak maxima of graphene (284.0 eV), whereas the introduction of six or more pentagons shifted the calculated peak maximum toward low binding energies because the number of connected pentagons increased. The presence of pentagons also influenced FWHMs. Introduction of six pentagons increased the calculated FWHMs from 1.25 to 1.45 eV, whereas introduction of eight or more pentagons decreased the FWHMs. The FWHM reached at 1.15 eV by introducing twelve pentagons (fullerene). These calculated shifts and FWHMs were close to the actual shifts of graphite (284.0 eV) and fullerene (282.9 eV) and FWHMs of graphite (1.25 eV) and fullerene (1.15 eV). Based on the calculated and the actual results, we proposed peak shifts and FWHMs of graphene with the different number of pentagons, which can be utilized for analyzing actual XPS spectra. Proposed FWHMs can be adjusted by measuring actual FWHMs using each device.

© 2015 Elsevier B.V.All rights reserved. Vapor-phase cyclodehydration of diethylene glycol (DEG) into 1,4-dioxane (DOX) were performed over several solid acid catalysts, such as Al2O3, SiO2-Al2O3, Beta and MFI zeolites. All the catalytic activity gradually decreased with time on stream, especially Beta and MFI zeolites with strong acidic property. The catalysts were modified with silver metal for stabilizing the catalytic activity: Al2O3 modified with 1 wt.% Ag2O showed the best catalytic performance. Characterizations such as XRD, TPD and FTIR were performed for analyzing the carbonaceous compound deposited on the catalysts after reaction and investigating the effect of the addition of Ag2O onto Al2O3. Polyethylene glycol was proposed as the carbonaceous compound by FTIR analysis. The modification of Ag was found to decrease the averaged acid strength of Al2O3, which is supposed to be effective for inhibiting carbon deposition and stabilizing the catalytic activity. It was also found that H2, as a carrier gas, was indispensable for stabilizing the conversion of DEG into DOX. Silver metal would work as a remover of the product on the catalyst surface together with H2 to prevent carbon deposition. Over Al2O3 modified with 1 wt.% Ag2O, a stable DOX selectivity of 90% with a complete conversion was achieved at 250 °C and a contact time of 156.8 g h mol-1.

© 2015 Elsevier B.V. Vapor-phase catalytic conversion of glycerol into propylene was performed over Cu/Al2O3 and acid-loaded Cu/Al2O3 catalysts in an H2 flow at ambient pressure. Acidic substances such as WO3, MoO3, V2O5 and H3PO4 were loaded on a commercial Cu/Al2O3. The addition of WO3 was found to be effective for promoting the formation of 1-propanol and propylene from glycerol, and 9.3wt% WO3-loaded Cu/Al2O3 (WO3/Cu/Al2O3) catalyst showed the best catalytic performance. WO3/Cu/Al2O3 calcined at a low temperature of 320°C had the largest number of acid sites and gave a 1-proponol selectivity of 38.2% and a propylene selectivity of 47.4% in an H2 flow at 250°C. The catalytic reaction of glycerol was performed over double-bed catalysts, in which WO3/Cu/Al2O3 was charged in the upper bed and a commercial silica-alumina was charged in the lower bed, to promote the conversion of 1-propanol into propylene. A high propylene selectivity of 84.8% was obtained over the double-bed catalysts at 100% glycerol conversion. An efficient catalytic process for the production of propylene from glycerol was proposed.

The bromination reactivity of azulene, naphthalene, and graphene with pentagonal, hexagonal zigzag and armchair, and heptagonal edges was theoretically estimated by density functional theory calculation and experimentally clarified by analyzing bromination of azulene and naphthalene using gas chromatography-mass spectrometry and ultraviolet-visible spectroscopy. The experimental and theoretical bromination reactivity of azulene with one pentagon and one heptagon was higher than that of naphthalene with two hexagons because of electron-rich carbon atoms on the pentagon. On the other hand, the tendency of theoretical bromination reactivity of pentagonal, hexagonal, and heptagonal edges on graphene was totally opposite to that on azulene and naphthalene. The order of the bromination reactivity of graphene edges was hexagonal zigzag > pentagonal > heptagonal and hexagonal armchair edges. The highest reactivity of hexagonal zigzag edges can be explained by the largest amount of electrons of carbon atoms among all of edges of graphene.

© 2014 Elsevier B.V. All rights reserved. Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) was investigated over rare earth oxide catalysts and In2O3 at around 400 ° C. In the dehydration of 2,3-BDO over Sc2O3,1,3-butadiene was mainly produced together with butanone, 2-methyl-propanal, 2-methyl-propanol, 3-buten-2-ol, and butene isomers. Sc2O3 calcined at 800°C showed the highest 1,3-butadiene yield of 88.3% at 411 °C in H2 carrier gas flow. Since 3-buten-2-ol is produced selectively from 2,3-BDO over Sc2O3 at a low temperature of 325 °C, 3-buten-2-ol rather than butanone is a probable intermediate from 2,3-BDO to 1,3-butadiene. 3-Buten-2-ol is readily converted into 1,3-butadiene at temperatures lower than 411 °C over Sc2O3 and Al2O3. In addition, double-bed catalysts composed of an upper catalyst bed of Sc2O3 and a lower of Al2O3 successfully converted 2,3-BDO directly into 1,3-butadiene with a stable selectivity higher than 94% at 318°C and 100% conversion of 2,3-BDO.

X-ray photoelectron spectroscopy (XPS) has been frequently utilized to analyze the structures of carbon materials. However, few types of defects such as functional groups have been identified and reported, and some of these assignments are controversial. For example, the structures of oxygen-containing functional groups of carbon materials such as graphite oxide and graphene oxide are still under debate. Reported assignments for the C1s spectra of nitrogen-containing functional groups in carbon materials are few and there has been little discussion of such spectra. One effective method to clarify the structures of carbon materials in detail is simulation of XPS spectra using computational chemistry. This work explains the current problems for the XPS analysis of the C1s spectra of carbon materials and suggests the peak positions of various oxygen- and nitrogen-containing functional groups in addition to their full width at half maximum.

The vapor-phase dehydration of 1,2-propanediol (1,2-PDO) was performed over various supported acidic oxide catalysts. Silica-supported WO3 catalyst shows the highest catalytic activity for propanal formation than other supported catalysts. A high and stable propanal selectivity of 93.5% was attained in H-2 atmosphere over 18.2%WO3-loaded silica catalyst using 20 wt.% 1,2-PDO aqueous solution as the reactant. The conversion of 1,2-PDO and the selectivity to propanal over the silica-supported WO3 were significantly affected by the calcination temperature of the catalysts. Since the high calcination temperatures decrease both the number of acid sites and the surface area of the catalysts, they decrease both the conversion of 1,2-PDO and the selectivity to propanal. The appropriate calcination temperature for silica-supported WO3 catalysts is 320 degrees C. The conversion of 1,2-PDO and the selectivity to propanal were also affected by the reaction temperature, the concentration of 1,2-PDO and the amount of catalyst used. A high propanal selectivity of 89.1% with a complete 1,2-PDO conversion was obtained at 250 degrees C over 3 g of 18.2% WO3-loaded silica catalyst when pure 1,2-PDO was used as the reactant. (c) 2014 Elsevier B.V. All rights reserved.