Publications by authors named "Muneyoshi Yamada"

In situ Co K-edge quick-EXAFS (QEXAFS) coupled with temperature-programmed oxidation as well as ex situ XAFS was applied to investigating the mechanism for enhancing the dispersion of Co(3)O(4) nanoparticles in a calcined Co/SiO(2) Fischer-Tropsch synthesis catalyst prepared by adding triethylene glycol (TEG) to a Co(NO(3))(2).6H(2)O impregnating solution. Ex situ Co K-edge XAFS indicated that, regardless of whether the catalysts were prepared with or without using TEG, the hexaaqua Co (II) complex was formed in impregnated samples which then underwent the dehydration process to some extent during the subsequent drying step at 393 K.

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Ni species on the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant were studied by Ni K-edge EXAFS and TEM measurement without contact of the catalysts with air. The Ni-Mo coordination shell related to the Ni-Mo-S phase was observed in the spent catalyst by quasi in situ Ni K-edge EXAFS measurement with a newly constructed high-pressure chamber. The coordination number of this shell was almost identical to that obtained by in situ Ni K-edge EXAFS measurement of the fresh catalyst sulfided at 1.

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To study the synergistic effect on the acidity and activity of Si-Al-Zr ternary oxide system, the mixture design of experiments was applied to prepare the ternary oxides by a sol-gel method, and rapid screening on dehydration of isopropanol and Friedel-Crafts reaction was conducted to determine the activities. These activities, amount of acid site determined by pyridine pulse, and specific surface area, were correlated with the oxide composition by means of support vector machine. Clear synergy among the Si-Al-Zr was observed on the acidic character and the surface area, whereas no synergy between Al-Zr was observed on the catalytic activities.

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To obtain direct evidence of the formation of the Ni-Mo-S phase on NiMo/Al(2)O(3) catalysts under high-pressure hydrodesulfurization conditions, a high-pressure EXAFS chamber has been constructed and used to investigate the coordination structure of Ni and Mo species on the catalysts sulfided at high pressure. The high-pressure chamber was designed to have a low dead volume and was equipped with polybenzimidazole X-ray windows. Ni K-edge k(3)chi(k) spectra with high signal-to-noise ratio were obtained using this high-pressure chamber for the NiMo/Al(2)O(3) catalyst sulfided at 613 K and 1.

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A high-throughput screening (HTS) reactor for high-pressure oxidative reforming of methane in a direct reaction route was developed. With a combination of catalyst preparation by a split-and-pool method and HTS, Ni-K/alpha-Al(2)O(3) catalyst was found to show high activity under 1 MPa at 650 degrees C with high selectivity even when O(2) conversion is less than 100%. The HTS reactor required a new simple syngas detector operable under high pressure because the number of parallel reactor is limited when equipped with the conventional detection system.

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The Rh/CeO2/M (M = SiO2, Al2O3, and ZrO2) type catalysts with various compositions have been prepared and investigated in the gasification of cellulose, a model compound of biomass, in a fluidized bed reactor at 500-700 degrees C. The conventional nickel and dolomite catalysts have also been investigated. Among the catalysts, Rh/CeO2/SiO2 with 35% CeO2 has been found to be the best catalyst with respect to the carbon conversion to gas and product distribution.

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