Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

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.

DOI： 10.3390/catal10121392

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© 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.

DOI： 10.1016/j.mcat.2019.110399

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© 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.

DOI： 10.1016/j.apcata.2019.02.013

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Here we report a novel aspect of molecular chaperone prefoldin (PFD) as a biomaterial in the biocatalytic synthesis of gold nanoparticles (AuNPs) using glycerol dehydrogenase (GLD). We found that PFD could inhibit the aggregation of AuNPs during the biosynthesis, leading to the formation of AuNPs with controlled size distribution.

DOI： 10.1039/c8bm01026a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Bimodal porous alumina was prepared from the solution with aluminum chloride and 1,2-propylene oxide by adding propylene glycol oligomers (PPG). Because of hydrophobic nature of PPG, the addition of PPG induces phase separation during sol-gel reaction, and macroporous morphologies are formed by fixing transitional structure of phase separation. Since ethanol works as a co-solvent, the macropore size of the obtained gel can be increased by decreasing ethanol content. Change in the concentration of other constituents such as PPG has also an effect to control morphologies through changing the timing of phase separation and sol-gel transition. (C) 2017 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.17062

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Rare earth hydroxide nitrates are prepared from rare earth nitrates by hydrothermal treatment. Three crystal phases, M(OH) 3 (M1), M-2(OH)(5.14)(NO3)(0.86)center dot H2O (M2), and M4O(OH)(9)NO3 (M4) are identified. The crystal phase systematically changes from M1 to M4 through M2 with decreasing radius of rare earth cation. Morphology of nanocrystal depends on the crystal phase. M1 and M4 phases grow to be nanorod, and M2 to nanoplate. (C) 2017 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.17072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Catalytic activity of rare earth oxides (REOs) in the vapor-phase dehydration of 1,4-butanediol to produce 3-buten-1-ol varies with lattice parameters of REOs. In order to clarify the adsorption structure and the reaction mechanism, adsorption energy of 1,4-butanediol on bixbyite REO, such as SC2O3, Y2O3, Dy2O3, Ho2O3, and Er2O3, {222} surface was calculated with density functional theory (DFT), and paired interacting orbitals (PIO) calculation of the adsorption state between 1,4-butanediol and Er2O3 was executed. The DFT study elucidates that the catalytic activity is correlated with adsorption energy. The PIO study clarifies the interactions between the reactive atoms of 1,4-butanediol and Er2O3 surface: tridentate interactions between a position-2 hydrogen atom of diol and an oxygen anion on Er2O3 and between each OH group of diol and erbium cations on Er2O3, and an intramolecular repulsive interaction between the position-1 carbon atom and the oxygen atom of OH group are observed. These results suggest that the position-2 hydrogen atom is firstly abstracted by a basic oxygen anion and that the position-1 hydroxyl group is subsequently abstracted by an acidic erbium cation. Another OH group on position 4 plays an important role of anchoring the diol to the Er2O3 surface. Therefore, it is proved that the dehydration of 1,4-butanediol over REOs proceeds via acid-base concerted mechanism. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cattod.2013.08.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Vapor-phase catalytic dehydration of 1,2-propanediol was investigated over several solid acid catalysts, such as alumina, silica alumina, HY zeolite, and beta-zeolite. These acids catalyzed the dehydration of 1,2-propanediol to produce propanal (Figure 1), while zeolites were particularly deactivated because of deposition of carbonaceous species. An amorphous silica-alumina was modified with metals such as Ag and Cu to stabilize the catalytic activity under hydrogen flow conditions. Ag-modified silica alumina is a promising catalyst for the production of propanal from 1,2-propanediol.

DOI： 10.1246/cl.131106

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Dimerization of 1,3-butadiene was investigated in a closed batch system under high-pressure conditions. 4-Vinylcyclohexene was mainly produced without using any solvents or catalysts at temperatures of 150-215 degrees C. The conversion of 1,3-butadiene was significantly dependent on the temperature and pressure. 1,3-Butadiene was converted to 4-vinylcyclohexene at selectivity higher than 90 mol % with by-products of 1,5-cyclooctadiene and 1,2-divinylcyclobutane. Large charges of reactant are efficient in achieving high conversions of 1,3-butadiene. Use of solvents, which dilute the reactant and absorb the reaction heat, is not favorable in the present dimerization of 1,3-butadiene under pressured conditions.

DOI： 10.1246/bcsj.20120333

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Syntheses of unsaturated alcohols in the vapor-phase catalytic dehydration of alkanediols over rare earth oxides are reviewed. CeO2 effectively catalyzes the dehydration of 1,3-butanediol to produce 3-buten-2-ol and trans-2-buten-1-ol. Heavy rare earth oxides such as Er2O3, Yb2O3, and Lu2O3 selectively catalyze the dehydration of 1,4-butanediol to produce 3-buten-1-ol. In the dehydration of 1,5-pentanediol, Yb2O3, Lu 2O3, and Sc0.5Yb1.5O3 catalysts efficiently work to produce 4-penten-1-ol. The active and selective oxides are composed of large particles with well-crystallized fluorite or bixbyite structure. Small oxide particles with poor crystallinity decrease the selectivity to unsaturated alcohols because of their dehydrogenation ability. In the reactions of different alkanediols, the reactivity of alkanediol depends on the length between the OH groups as well as on the geometry of the catalyst surface, which is affected by the distance between rare earth cations. For example, over CeO2, the reactivity order of the alkanediols is 1,3-butanediol > 1,4-butanediol > 1,5-pentanediol > 1,6-hexanediol. Quantum calculations support a probable reaction mechanism: OH groups and the H of the position-2 methylene group of 1,3-butanediol are interacted with the surface Ce4+ to form a tridentate coordination, and the abstraction of the position-2 H by Ce4+ is the initial step of 1,3-butanediol dehydration in the formation of unsaturated alcohols. © 2013 American Chemical Society.

DOI： 10.1021/cs300781v

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Solvent-free Diels-Alder reactions were carried out by heating a mixture of a volatile diene, such as 1,3-butadiene, isoprene, or 2,3-dimethyl-1,3-butadiene, and a dienophile, such as methyl vinyl ketone, methyl acrylate, or maleic anhydride, in a closed batch reactor. High yields of Diels-Alder products were obtained without using solvents and catalysts within a short reaction time in most of the reactions. In particular, several reactions of dienophiles with 1,3-butadiene, which is known as a diene with low reactivity because of its gaseous form, also proceeded with high yields of Diels-Alder products in the closed batch reactor under conditions pressured by the reactant vapor. Solvent-free reactions provided high yields compared to reactions in solvent since the reaction heat directly resulted in increasing the reaction temperature and pressure. Energy in the exothermic reaction was used effectively in the closed batch system under solvent-free conditions.

DOI： 10.1246/bcsj.20120247

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vapor-phase dehydration of 1,4- and 1,5-alkanediols was investigated over three scandium ytterbium mixed oxides, Sc2-xYbxO3 (x = 0.5, 1.0, and 1.5), to produce the corresponding unsaturated alcohols. In the dehydration of 1,5-pentanediol, Sc0.5Yb1.5O3 was more active than simple rare earth oxides such as Sc2O3, Lu2O3, Yb2O3, and Tm2O3. The selectivity to 4-penten-1-ol surpassed 80 mol% over the Sc2-xYbxO3 catalysts. The highest formation rate of 4-penten-1-ol was obtained at x = 1.5 and affected by lattice parameter of cubic bixbyite Sc2-xYbxO3. In the dehydration of 1.4-butanediol. however, Tm2O3 was the most active among the catalysts. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.catcom.2012.07.018

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Silica-supported silver exhibited high catalytic activity in the dehydration of glycerol: glycerol was dehydrated into hydroxyacetone with the selectivity higher than 86% at 91% conversion over Ag/SiO2 in H-2 flow at 240 degrees C. Silver metal provides an active site and showed stable catalytic activity for the glycerol dehydration in H-2 atmosphere, while the dehydration activity decreased in N-2 atmosphere. The hydrogenation of hydroxyacetone into 1,2-propanediol and the decomposition to ethylene glycol did not proceed over silver.

DOI： 10.1246/cl.2012.965

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Er2O3 nanorods were successfully prepared with hydrothermal treatment without using organic additives such as surfactant, fatty acid, or alcohol. Er2O3 nanorods were obtained under high temperature and/or long reaction times. Er2O3 nanorods mainly exposed {440} and {400} facets on the surface. Er2O3 nanorods showed excellent catalytic activity compared to commercial Er2O3 nanoparticles in the dehydration of 1,4-butanediol to produce 3-buten-1-ol.

DOI： 10.1246/cl.2012.593

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Vapor-phase catalytic dehydration of 1,5-pentanediol was investigated over rare earth oxides (REOs) at 325-450 degrees C. The conversion of 1,5-pentanediol over REOs calcined at 700 and 800 degrees C was higher than that calcined at 500 degrees C. Sc2O3, Yb2O3, and Lu2O3 with cubic bixbyite structure showed the selectivity to 4-penten-1-ol with higher than 74 mol%, while REOs with hexagonal and monoclinic structures showed the selectivity with less than 50 mol%. Especially. Yb2O3 and Lu2O3 calcined at 1000 degrees C showed high formation rate of 4-penten-1-ol per specific surface area over 1 mmol h(-1) m(-2) at 400 degrees C. In the Yb2O3 catalyst calcined at 800 degrees C, the conversion of 1,5-pentanediol was increased up to 74.4 mol% with increasing contact time, together with stable selectivity to 4-penten-1-ol of 71.8 mol%. In comparing the reactivity of alkanediols to form the corresponding unsaturated alcohols over Yb2O3, we found the reactivity of alkanediols into the corresponding unsaturated alcohols was the following order: 1,4-butanediol >1,3-diols >> 1.5-pentanediol >> 1,6-hexanediol. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2012.01.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A series of rare earth oxides were investigated as catalysts in the ketonization of acetic acid. High selectivity to acetone over 99% was obtained by reacting acetic acid over rare earth oxides such as La2O3, CeO2, Pr6O11, and Nd2O3. Especially, Pr6O11 showed the highest yield of 80% at 350 degrees C among the 14 rare earth oxides. The bulk structure of CeO2 was stable during the ketonization, while the surface acetate species were observed over CeO2 after ketonization. In contrast, the other active rare earth oxides such as La2O3, Pr6O11, and Nd2O3 were mainly basic oxides due to the formation of bulk oxyacetate such as MO(AcO), where M is La, Pr, and Nd and AcO indicates CH3COO group, in the initial period of the reaction. In any case, the catalytic ketonization proceeds over the surface of the oxyacetates and CeO2. Catalytic cycle of the ketonization is composed of two steps: the decomposition of surface M2O(AcO)(4) to produce MO(AcO), acetone, and carbon dioxide and the regeneration of surface M2O(AcO)(4) by reacting MO(AcO) and acetic acid to produce water. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2011.06.011

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Event date： 2024.9

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Venue：愛媛大学城北キャンパス   Country：Japan  

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