Yuki Yamasaki

Synthesis of Pt-Entrapped Titanate Nanotubes

In this study, Pt-entrapped titanate nanotubes with approximately 10 to 15 nm in outer diameter and 5 nm in inner diameter and several hundreds in length were synthesized by a hydrothermal treatment of titanium oxide as a source material and a subsequent heat-treatment of the mixture of these titanate nanotube and a Pt salt. According to TEM observations, Pt nanocrystals with a few nm in diameter and 5 to 10 nm in length were contained in titanate nanotubes. These Pt nanocrystal-entrapped titanate nanotubes had the high photocatalytic properties, which are also expected to be a useful material for nanotechnology applications.

Microstructural Control of Mesoporous Bulk Composed of TiO2-Derived Titanate Nanotubes

The mesoporous bulks composed of TiO(2)-derived titanate nanotubes fabricated from a hydrothermal treatment of commercial TiO(2) particles in a concentrated NaOH aqueous solution were obtained by a hydrothermal hot-pressing (HHP) method and subsequent steam-curing process with HCl solutions. The mesopore size and sodium concentration for the bulky TiO(2)-derived titanate nanotubes were dependent on the treatment conditions on the steam curing process with HCl solutions. The effect of the sodium concentration (Na/Ti) on microstructures were examined on the steam curing process for the application of the bulky TiO(2)-derived titanate nanotubes to several new fields.

Evaluation of microstructures and properties of bulk mesoporous silica

Synthesis of mesoporous MCM-type bulks prepared by hydrothermal hot-pressing (HHP) method using MCM-type mesoporous powder was attempted. Scanning electron microscopy (SEM), bulk density measurement, N2 adsorption-desorption isotherms and formaldehyde adsorption test have been employed to characterize the bulky products. As a result, we succeeded in preparing a dense and strong mesoporous bulks with high BET over 1000 m2/g through the hydrothermal hot-pressing method under appropriate conditions.

Synthesis of Nanotubular Titanate from Titanium Using Hydrothermal Treatment

In this study, the synthesis of nanotubular titanate was attempted though heat-treatment in an oil bath (non-hydrothermal treatment), heat-treatment with stirring in an oil bath (non-hydrothermal treatment), or hydrothermal treatment for metal Ti in NaOH aqueous solution systems. Obtained products were characterized by various methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD results suggested that products obtained by both hydrothermal treatment and heat-treatment in an oil bath with and without stirring could be identified as H2Ti4O9H2O. From TEM observations, however, various morphologies for products obtained by these treatments were confirmed. Therefore, it was considered that morphologies of these products strongly depended on synthesis conditions.

Syntheses of Bulky Y-Zeolite by Hydrothermal Hot-Pressing (HHP) Technique

Synthesis of bulky Y-zeolite was attempted by a hydrothermal hot-pressing (HHP) method. These bulky products synthesized under hydrothermal conditions were identified as Y-zeolite single phase. Especially, bulky Y-zeolite having translucency, high density and large surface area was obtained by HHP treatment at 423K for 2h with 17wt% of 5M-NaOH solution. This solidified zeolite like single-crystal was considered to be made by dissolution and precipitation mechanism. High-density bulky zeolites can be expected as novel molecular sieves and catalysts with high activity.

Synthesis of Dense Mesoporous Silica with High Surface Area by Hydrothermal Hot-Pressing (HHP) Method

In this study, the synthesis of the bulky and dense mesoporous silica such as FSM was attempted by a hydrothermal hot-pressing (HHP) with a surfactant as a template and a subsequent calcination. According to TEM observation, the dense bulks obtained by HHP had a hexagonal mesopore structure. Also, these dense FSM bulks possessed high specific surface areas. Furthermore, Ag-supported dense FSM bulks were successfully synthesized by HHP with Ag salt and a subsequent calcination in H2. Thus, this HHP method is useful for synthesizing dense bulks and simultaneous supporting novel metals such as Ag on bulky FSM.