Synthesis of hierarchical zeolite and cobalt catalysts loading for C-N bond formation

Abstract

Zeolites are widely used as shape selective and ion exchange catalysts. Both properties are addressed in this work. To improve the shape selectivity of zeolite, we designed a surfactant based on a L-proline derivative to synthesize hierarchical zeolite. Design of chiral porous materials has garnered interest for applications due to their potential enantioselectivity and also their resultant separation property. Several approaches to introduce chirality into zeolites, via control of the pore connectivity or pore shape, have been suggested. While some were successful, the present zeolites have difficulty in chiral application because their micropores are relatively large, and thus direct interaction with adjacent chiral molecules is difficult, or because the structure has multiple handedness due to the non-chiral structure directing agent. In this work, in the synthesis of zeolite, an L-proline derivative based surfactant was used as a structure-directing agent. It is anticipated that this surfactant will introduce chirality inside the pores, as it can efficiently restrain mobility because of its long alkyl chains. XRD patterns show that the resultant material has a MFI-like crystalline structure and $N_2$ adsorp-tion/desorption isotherms confirm its mesoporosity. Further characterization to verify the chirality of the arrangement is required. With regard to the ion exchange property of zeolite, we studied transition metal exchanged zeolite. Zeolites containing transition metal ions have shown promising activity as heterogeneous catalysts in pollution abatement and selective oxidation reactions. However, the preceding catalysts have been operated on a restricted scope due to the diffusion limitation of conventional zeolite. Here, we have studied a heterogeneous catalytic system using a recently developed hierarchical MFI zeolite produced by a surfactant-type structure-directing agent. The amination of 5-methylbenzoxazole with morpholine was accomplished by using...