Synthesis of Nano-Sized BZSM-5 Zeolite Crystals

zeolite materials are widely used in various applications such as gas separation, catalysis, adsorbents and ion exchangers. Zeolites also exhibit high potentials for continuous separation of gas/vapor mixtures, and applications in membrane reactors as well as sensitive chemical sensors. The search of new properties of known zeolites continues to be a subject of scientific research, where a recent trend is the synthesis of zeolitic materials with a low dimensionality, that is, nano-sized zeolites. It is well known that nano-sized zeolites have high surface areas which reduces the diffusion path and can be assembled into thin films structures such as membranes and chemical sensors. Substitution of silicon in crystalline molecular sieve structures by various hetroatoms has been a topic of interest for past few decades. The isomorphous substitution of Al and/or Si by other tri- and tetravalent metal ions is generally considered as a tool for modifying the acidic and catalytic properties of zeolites. Synthesis of micron-size BZSM-5 crystals has been reported in a previous work [1]. So far, no viable synthesis method has been reported for the preparation of nano-size BZSM-5 crystals. In this work, Synthesis of zeolite BZSM-5 in the form of nano-crystals from clear homogeneous solution with Si/B ratio of 100 has been achieved. This method consists of hydrothermal crystallization from clear solutions in an open polypropylene vessel at atmospheric pressure under reflux. The ultimate size of the discrete crystals is in the range of 100-200 nm with a narrow particle size distribution. The products were characterized by means of X-ray diffraction, FTIR, and SEM analyses. The effects of synthesis time and temperature on the crystallinity of the zeolite and the crystals morphology were also investigated. The synthesis route turned out to be successful and well reproducible