Papers by Author: Masaki Maeda

Abstract: Relationship of the adsorption behaviors of phosphorus with several natural materials and artificial HAS-clay with various chemical compositions was investigated. The amounts of phosphorus adsorbed by them were closely related with the contents of aluminum in the material. It was found that the higher the aluminum contents of material, larger the amount of phosphorus were adsorbed.

Abstract: Titanium dioxide photocatalyst films were prepared by dip-coating method using titanium dioxide sol solution in order to research the H₂O addition effect on the photocatalytic activities. The sol solution was prepared with titanium tetra-isopropoxide, urea and 2-methoxyethanol, then irradiated ultraviolet light and added distilled H₂O. The substrates for the dip-coating were fused silica plates and as-prepared films were dried at 100 °C then annealed at 650 °C. The films prepared by these methods showed visible light absorption in wavelengths longer than 380 nm and accelerated photodegradation of methylene blue by visible light irradiation. Furthermore, the photocatalytic activities of these films were depending on the H₂O additions to the sol solution.

Abstract: Phosphorus was one of the causative materials of eutrophication that was widely generated in the water system, for instance, the rivers, lakes, and marshes all over the world. The removal method using the phosphorus adsorption ability of volcanic ash fall deposits contained especially the amorphous alumino-silicate mineral was examined. To improve the practicality of durability and the adsorption ability of the volcanic ash fall deposits was heated within the range from 100 to 1100degrees. It was found that the phosphorus adsorption ability of the material was increased as the calcinating temperature was raised, and reached the maximum value at about 600degrees. The amount of adsorption of phosphorus had decreased rapidly when the material was heating to 600degrees or more.

Abstract: . Preferential oxidation (PROX) of CO in the presence of H2 is an important reaction to maintain stable operation of polymer electrolyte fuel cells (PEFCs) since their anode catalyst can be poisoned by trace amount of CO. In this study, we examined PROX reactions mediated by Pt catalysts prepared using several mesoporous silica and aluminosilicate supports such as imogolite (IM), allophane (AP), silica aerogel (SAG), and an amorphous hydroxyl aluminosilicate developed in our research group (HAS). The selectivity of CO oxidation gradually decreased from 80 to 60 % with increasing temperature from 323 to 473 K for Pt/HAS catalyst whereas it increased with temperature from 10 to 40 % for Pt/IM, Pt/AP, Pt/SAG catalysts. These results indicate that Pt supported on HAS may be effective for low-temperature PROX reactions.

Abstract: Titanium dioxide sol solution was prepared using titanium tetra-isopropoxide, urea, 2-methoxyethanol. After that, ultraviolet light was irradiated to the sol solution, then, H2O was added to the solution. The prepared sol solution was dip-coated onto fused silica plates. The as-prepared films were dried at 100 °C and then annealed at 650 °C. The annealed films were anatase type titanium dioxides. Visible light absorption by the films was observed in wavelengths longer than 380 nm. Also, photodegradation of methylene blue by visible light irradiation was accelerated in the presence of the films prepared by these methods.