Creating Synthetic Zeolite
in the Shape of Tubes, Fibers and Fabrics

@@ Japan Chemical Innovation Institute and Catalyst Design Group of our Institute have developed a novel technique to control zeolite formation, termed "dynamic bulk-material dissolution' (DBMD), and by applying this technique, we successfully synthesized a tube-shaped zeolite. This work has been carried out by the support of New Energy and Industrial Technology Development Organization (NEDO) for and AIST project on "Technology for Novel Highly Functional Materials - Harmonized Molecular Materials - Microporous Materials."
@@ Preparation of the tube-shaped zeolites by DBMD: A piece of quartz glass tube (ca. 16.5 mm long, 10 mm external diameter and 8 mm internal diameter; 17.5 mmol SiO₂) was fixed with a piece of polytetrafluoroethylene (PTFE) rod in a PTFE sleeve (capacity 23 mL) equipped for an autoclave. The sleeve was filled with an aqueous solution consisting of tetra-n-propylammonium hydroxide (TPAOH), hydrogen fluoride (HF), and approximately 50 mg of MFI seed crystals. After the autoclave had been rotated around a horizontal axis at 10 rpm in a convection oven at 200�� for 61 days, a tube-shaped MFI zeolite was obtained and its shape was very close to that of the source bulk material.
@@ Zeolites are crystalline microporous material that has pores with precise and regular diameters and intervals. This porous material which, in other words, called molecular sieve, have a pore diameter measuring under 1 nm (10^-9 mm), the size almost equivalent to the low molecule compounds. Due to this property, zeolites are attracting much attention as a valuable and important material applicable as ion exchange material, adsorption and separation processing material, and high-performance catalyst in industrial fields.
@@ However, the application of the zeolites has been rather limited because they are generally obtained as very small crystals ranging from several to some tens of micrometers (10^-6 mm). Therefore, the success in a technique to prepare zeolites with appropriate shapes will promote the development of the effective catalytic processing using zeolitic membrane catalysis of appropriate shapes which has not been realized so far. Moreover, the application of the DBMD enables to convert the inner part of glass capillary tubes into zeolite, which makes the design of microreactors using these capillary tubes possible. It can also be applied to a rapid evaluation equipment of various kinds of catalytic reaction processes combined with computer techniques.
@@ The characteristic of the dynamic bulk-material dissolution (DMBD) technique developed here is first to prepare raw material silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃) compound, subsequently replace it with zeolite from the surface to inside and finally the raw material is converted to a zeolite crystal. This technique is applied also to synthesize zeolitic fibers and fabrics.
@@ Since the shape control of zeolitic materials is an important technical issue for industrial use of zeolites, we believe that the DBMD technique will provide a practical solution. The DBMD technique can be applied to zeolites of many different shapes, thus the knowledge and experience of the conventional synthesizing techniques accumulated up to the present should be adaptable to the DBMD technique without difficulty. Therefore, it is expected to develop into a technique to control the shapes more freely in the future research.