TAILIEUCHUNG - Fe-MCM-22 zeolites: synthesis and study about the states of iron
The Fe-MCM-22 zeolite was successfully synthesized with hexametylenimine template. Several physicochemical techniques (XRD, SEM, BET, AAS, IR and ESR) have been used to characterize this zeolite. Iron exists under three states: isolated ions in tetrahedral lattice positions, in octahedral coordination as isolated ions at cationic positions and as aggregated oxide species or hydroxide phases. | Journal of Chemistry, Vol. 45 (3), P. 368 - 372, 2007 Fe-MCM-22 zeolite: synthesis and study about the states of iron Received 13 June 2006 Ngo Thi Thuan1, Tran Thi Nhu Mai1, Giang Thi Phuong Ly1, Le Xuan Tuan 1 Faculty of chemistry, VNUH, 19 Le Thanh Tong Street, Hanoi Vietnam 2 Service de Chimie Analytique et Chimie des Interfaces (CHANI) – CP 255 Belgium Summary The Fe-MCM-22 zeolite was successfully synthesized with hexametylenimine template. Several physicochemical techniques (XRD, SEM, BET, AAS, IR and ESR) have been used to characterize this zeolite. Iron exists under three states: isolated ions in tetrahedral lattice positions, in octahedral coordination as isolated ions at cationic positions and as aggregated oxide species or hydroxide phases. Keywords: Fe-MCM-22 zeolite, synthesis, characterization, framework iron. I - Introduction MCM-22 zeolite is a new patent given by Cooperation Mobil Oil [1]. In the last ten years, its properties were thoroughly investigated. The framework topology of MCM-22 has been shown to consist of layers linked together along the c-axis by oxygen bridges and contain two independent pore systems. Within the layers are two-dimensional sinusoidal 10-MR channels ( × Å), and between two adjacent layers are 12-MR supercages (~ × × Å) communicating each other through 10-MR apertures ( × Å). In addition, its typical thin platelet morphology results in high external surface area [2]. Dealuminated acid forms of MCM-22 have been characterized, concluding that the acidic properties are very similar to HZSM-5 zeolite [3]. Nowadays, the synthesis parameters for the preparation of MCM-22 zeolite have been optimized [4]. Formerly, zeolite used to be known as an acidic catalyst. It is well known that the addition of transition metals, especially iron, in initial gel 368 for zeolite synthesis was enormously studied. The presence of different iron species in zeolite created several new activities for this kind .
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