Cooperative Effect of Alkali Metal Cations in Zeolite Synthesis
Professor Tatsuya Okubo, Department of Chemical System Engineering, University of Tokyo, Tokyo 113-8656, Japan
5 May 2009
Lecture Theatre 1
Ibnu Sina Institute for Fundamental Science Studie
University Teknologi Malaysia
Abstract
Zeolites are hydrated, crystalline tectoaluminosilicates that are constructed from TO4 tetrahedra (T = tetrahedral atom, e.g. Si and Al). They contain well-ordered, nanometer-sized void spaces in their structures. Zeolites have been widely utilized in industry and in household products, for example as adsorbents, ion-exchangers, and catalysts, and have attracted considerable attention as host materials for various nanotechnology applications. Zeolites are synthesized from silicon and aluminum sources with alkali metal hydroxides under hydrothermal condition if they are not high-silica or pure-silica ones that require the addition of organic structure-directing agents. Alkali metal cations play various roles in zeolite synthesis. They contribute to the formation of the aluminosilicate precursors at the initial stage, and compensate for the negative charge of the framework as counter cations at the final stage. Also the hydrated cations play a role of structure-directing agent or pore filler [1,2]. Some zeolites are formed with specific alkali metal cations, and others are formed only when two different alkali metal cations are employed together. In this talk, our systematic approach to understand the cooperative effect of alkali metal cations will be introduced [3].
References
- 1. Toru Wakihara, Tatsuya Okubo, Hydrothermal Synthesis and Characterization of Zeolites, Chemistry Letters 34 (3), 276 (2005).
- 2. Toru Wakihara, Shinji Kohara, Gopinathan Sankar, Seijiro Saito, Manuel Sanchez-Sanchez, Arian R. Overweg, Wei Fan, Masaru Ogura and Tatsuya Okubo, A New Approach to the Determination of Atomic-architecture of Amorphous Zeolite Precursors by High-energy X-ray Diffraction Technique, Physical Chemistry Chemical Physics 8 (2), 224-227 (2006).
- 3. Yasuhiro Suzuki, Toru Wakihara, Keiji Itabashi, Masaru Ogura and Tatsuya Okubo, Cooperative Effect of Sodium and Potassium Cations on Synthesis of Ferrierite, Topics in Catalysis 52 (1-2), 67-74 (2009).