Research

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Introduction

We are interested in developments of environmentally benign process using novel metal oxide based functional materials such as zeolite, mesoporous materials, layered silicates, and polyoxometalate. We are investigating synthesis, characterization, and application of them.

Currently ongoing researches are

  1. Development of novel synthetic methods of zeolites by interzeolite conversion.
  2. Development of novel functional material for CO2 capture and conversion in air or exhaust gas.
  3. Development of novel synthetic methods of zeolites from layered silicates.
  4. Development of zeolite catalysts for conversion of bioethanol to propylene.
  5. Development of effective ammonia selective catalytic reduction (NH3-SCR) based on zeolites.
  6. Development of separation filter based on zeolites.
  7. Design of adsorption site and catalytic active site in ordered layered spaces in layered silicates.
  8. Development of novel polyoxometalate materials.

Zeolite

Zeolites are one of the most important crystalline silicates material having microporous (2.0 nm ≥ dP) in industry. Because of their attractive properties (adsorption, catalytic and ion exchange), they are utilized for the environmentally friendly and economically benefit application such as petrochemical industries, oil refineries and fine chemicals industries. We are investigating synthesis of many types of zeolite by interzeolite conversin of several types of zeolites. The crystallization rates and heat- or acid resistances of zeolite using starting zeolites are notably improved compared to conventional hydrothermal synthesis using amorphous aluminosilicate gels. This characteristic enhancement results from the generation of locally ordered aluminosilicate species (nanoparts) thorough the decomposition/dissolution of the starting zeolite, resulting in assembly and evoluation into another type of zeolite. Our present concern is how to apply such zeolite obtained by interzeolite conversion to automotive emission control, hydrogen storage, biomass conversion, effective and economic separation technique in fine chemicals industries and so on.

Layered silicate

Crystalline layered silicates composed of 2-dimentional silicate sheets with nanometer thickness having the silicate framework composed SiO4 tetrahedron possess interlayer exchangeable cations and large interlayer space. By using reactive neighboring silanol (SiOH/SiO–) groups in the interlayer, various post treatment including ion-exchange, silylation and pillaring are available. Accurate arrangement of SiOH/SiO– groups located in the crystallographically defined position facilitate more free design of advanced and innovative inorganic or hybrid materials. Recently, we reported the successful synthesis and structural analysis of new layered silicates, Hiroshima University Silicates (HUSs). We are now investigating their unique adsorption, ion-exchange properties, and potential as precursors for catalysts and porous materials freely and precise constructed local structure.

Polyoxometalate

Polyoxometalates are anionic metal oxide molecules of W, Mo, Nb, and V as a main metals. Polyoxometalates can incorporate almost all elements in Periodic table and form variety of structure. In addition, polyoxometalates with proton as a counter cation have high acidity and polyoxometalates show multiple redox properties. Therefore, polyoxomelates have attracted much attention as catalysts. Our current researches are 1. Synthesis and characterization of new polyoxometalates, 2. Self-assembly of polyoxometalate to infinite metal oxides, 3. Application of polyoxometalates as catalysts, and 4. Synthesis of ordered porous materials based on polyoxometalates.

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