engleski

The Study of the Formation of Zincosilicate Zeolite RUB-17 (RSN- Type)

By classical definition, zeolites are crystalline alumosilicate materials with well-defined system of channels and cages having size lower than 2 nm. This definition was further extended to all materials possessing structure features typical for zeolites, so called zeotypes. Zeotypes are built of tetrahedra of oxygen atoms bonded to central T atom (T = Si, Al, Zn, Ge, P, Ga, …) and connected via vertices thus forming porous framework. Taking into account possible bonding angles and energy restrictions, there are over two millions hypothetical zeolite structures. Zeolites are widely used materials, ranging from ion-exchange and molecular sieving to catalysis in oil refinement and drug delivery in medicine. For this reason engineering of their structure and properties in line with the requirements of a particular application would be beneficial for improving their performance. In spite of numerous studies performed in this field, still many of the results are based on empirical experience, rather than on profound comprehension of the basic processes of zeolite formation. It was perceived that some zeolite building units are more often formed in the presence of a certain T-atom than when others are used (1). Besides, depending on the synthesis conditions applied, different final products can be formed from the same initial reaction system (2). Herein we report the study of zincosilicte RUB-17 – three-membered ring containing framework type RSN (3). The methods employed to study the precursors and final products are XRD, GISAXS, TG, Raman, IR, UV/VIS and NMR spectroscopy. The effect of type of the potential framework T-atoms which were found to form three- membered rings in zeolite frameworks (Al, B, Ge, Li and Mg) is investigated. The collected data indicate that under studied conditions the RSN framework is formed exclusively in zinc containing systems. In order to get more insight into RSN formation several different zinc sources are used. Besides the synthesis conditions the necessity of the presence of structure directing agent in the RUB-17 reaction mixture is going to be discussed. The obtain data can be used for control of zeolite formation in similar systems. In addition, the potential of the prepared material to be used as semiconductor is investigated.

zeotype ; zinc source ; T atom

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