(90b) Fabrication of Unique Aei-Type Aluminosilicate with Sheet-like Morphology

We developed a new class of AEI-type aluminosilicate with sheet-like morphology to improve the molecular diffusibility, and it was applied to the direct conversion from propene to butenes (PTB). AEI-type aluminosilicate, represented by SSZ-39, is paid a lot of attention as an excellent catalyst for lower olefin production [1, 2]. Although this structure has several similarities in CHA structure, it showed different shape selectivity for lower olefin. While CHA-type zeolites can be synthesized with a wide range of Si/Al ratio, that of AEI-type zeolite cannot be controlled. Hence, other approaches for decreasing the number of acid sites are required to extend the catalytic lifetime. Previously, we reported that the development of B-containing AEI-type zeolites as a catalyst for ETP reaction, where the amount of acid sites was decreased by the substitution of Al atoms by B atoms [3]. In this time, we focused on the synthesis of sheet-like crystals as the strategy for the improvement of the molecular diffusibility.

Various surfactants have been used as crystal growth inhibitors (CGI) in the zeolite synthesis to control the crystal size and/or morphology to date [4-6]. The role of CGI has also proposed. The CGI interacted with crystal nuclei [4]. Then, the crystal growth was limited by the interaction between CGI and the reactive sites of inorganic species. As a result, unusual size and/or shape of particles were obtained. However, there are only a few reports on the application of this synthesis method for 8 MR aluminosilicate zeolite. Syed et al. reported sub-micrometric-sized SAPO-34 crystallites by a facile surfactant-assisted hydrothermal synthesis, where cetyltrimethylammonium bromide (CTAB) was used as a CGI [7]. They showed a longer catalytic lifetime for MTO reaction. Thus, the addition of CGI might be an effective method for not only large-pore zeolites but also small-pore ones. Therefore, CGI-assisted hydrothermal synthesis was applied to the fabrication of a new class of AEI-type aluminosilicate, and its catalytic activity for the propene to butenes reaction was investigated in this paper.

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