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A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO2). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO2 for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H2: 1 MPa, CO2: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min. [ABSTRACT FROM AUTHOR]

A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO2). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO2 for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H2: 1 MPa, CO2: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min. [ABSTRACT FROM AUTHOR]

Pt-free cathode catalysts for polymer electrolyte membrane fuel cells have been prepared by multi-step pyrolysis of FePc and PhRs, in the best of which show extensively high initial cell performance and good durability compared to other present precious-metal-free cathode catalysts to date. [ABSTRACT FROM AUTHOR]

Pt-free cathode catalysts for polymer electrolyte membrane fuel cells have been prepared by multi-step pyrolysis of FePc and PhRs, in the best of which show extensively high initial cell performance and good durability compared to other present precious-metal-free cathode catalysts to date. [ABSTRACT FROM AUTHOR]

Abstract: Barium titanate (BaTiO3: BT) nanoparticles were synthesized by the hydrothermal method in the presence of dispersants using a continuous supercritical flow reaction system. The reactants of TiO2 sol/Ba(NO3)2 mixed solution and KOH solution were used as starting materials and that was heated quickly up to 400°C under the pressure of 30MPa for 8ms as reaction time. The dispersant solution such as polyacrylic acid (PAA) and polyoxyethylene(20) sorbitan monooleate (Tween 80) was injected in the cooling process after the reaction. The crystal phase of the obtained particles was identified as perovskite cubic BaTiO3 by X-ray diffractometry (XRD) and Raman spectroscopy. Raman spectra and thermogravimetric data revealed that PAA and Tween 80 fabricated hybrid BT nanoparicles. Primarily particle size of the BaTiO3 nanoparticle was determined by means of BET surface area, as small as less than 10nm irrespective of dispersants. In contrast, dispersed particle size in solution measured by dynamic light scattering (DLS) technique decreased from 282nm to less than 100nm depending on the dispersant. Aggregation of BaTiO3 nanoparticles might be depressed in the presence of dispersants, especially PAA is the most effective among the dispersants examined. [ABSTRACT FROM AUTHOR]

Abstract: Highly crystalline γ-alumina (γ-Al2O3) nanoparticle was synthesized hydrothermally in supercritical water by using a continuous flow reaction system from the starting reagent of Al(NO3)3·9H2O. The study was performed under supercritical conditions of water; temperature ranging from 400 to 500°C, pressures from 25 to 35MPa and the reaction time was as short as 63ms to 3s. Products were characterized by XRD pattern, BET surface areas, transmission electron microscopy (TEM), and dynamic light scattering (DLS). XRD results revealed that γ-Al2O3 particles were obtained at 410°C or higher through the dehydroxylation reaction in supercritical water, while γ-AlOOH phase was predominant at 400°C. Primary particle size of γ-Al2O3 was about 4nm and did not depend on the reaction temperature and time. Furthermore, DLS results revealed that the secondary particle size of γ-Al2O3 dispersed in water increased with increasing reaction temperature and time probably due to particle aggregation. It is noteworthy that secondary particle sizes of γ-Al2O3 dispersed in aqueous solution decreased as the Al(NO3)3·9H2O concentration was increased, since particle aggregation was depressed by high zeta potential with lowering the pH. [Copyright &y& Elsevier]

Abstract: Highly crystalline BaTiO3 nanoparticle was synthesized rapidly by hydrothermal reaction in supercritical water using a continuous flow reactor. The reactant solution of 0.05M TiO2 sol and 0.06M Ba(OH)2 was used as starting materials and that was heated quickly up to 400°C under the pressure of 30MPa with in as short as 2s to 7ms reaction time. The X-ray diffraction (XRD) results revealed that the crystal phases of the obtained particles were only BaTiO3, indicating that the hydrothermal reaction in supercritical water was successfully proceeded under present reaction conditions. Particle size of the BaTiO3 nanoparticle was determined by means of BET surface area, as small as less than10nm with reducing the reaction time from 2s to 7ms. Furthermore, high-resolution transmission electron microscopy (TEM) image of BaTiO3 nanoparticles showed highly crystalline nature of BaTiO3, even if the time for crystallization of BaTiO3 was extremely reduced. The formation of highly crystalline BaTiO3 nanoparticles by the short reaction period is thought to be strongly attributed to the properties of supercritical water. Especially, lower dielectric constant property of supercritical water expected to accelerate the hydrothermal reaction of BaTiO3, and allowed the synthesizing of BaTiO3 nanoparticles only in 7ms. [Copyright &y& Elsevier]

Abstract: Pyrolysis of a mixture of Fe phthalocyanine and phenolic resin (FePc/PhRs) was studied to clarify the details of the preparation protocol of nitrogen-doped carbon-based materials for cathode catalysts in polymer electrolyte membrane fuel cells. TEM images show that nanoshell carbon is formed by the pyrolysis of FePc/PhRs in the temperature range of 600–800°C. The optimum pyrolysis temperature for the FePc/PhRs mixture was 600°C, where moderate conductivity and high nitrogen content of the prepared carbon were both satisfied. This catalyst showed a promising fuel cell performance with 1.01V open-circuit voltage and 0.33Wcm−2 maximum output, at 0.2MPa absolute pressure and 80°C. A detailed study of the carbonization process suggests that the presence of Fe species during carbonization process contributes to higher nitrogen content and growth of nanoshell structure of the resulting carbon. [Copyright &y& Elsevier]

A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO(2)). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO(2) for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 degrees C in 10 MPa (H(2): 1 MPa, CO(2): 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min.