하이드록실기를 갖는 2가 암모늄 양이온의 유기구조유도분자를 이용한 유무기 혼합 분자체의 합성, 특성분석 및 촉매특성에 관한 연구: ECR-40 분자체

Abstract

New routes for the synthesis of ECR-40 material, their characterization, and catalytic properties are described. A family of ECR-40 materials, denoted ECR-40F, ECR-40G, and ECR-40H, has been synthesized by using diquaternary ammonium ions as a new organic structure-directing agent and their as-made and calcined forms are extensively characterized by powder X-ray diffraction, scanning electron microscopy, thermal and elemental analyses, multinuclear MAS NMR, N2 sorption, and NH3 temperature-programmed desorption. The synthesis of ECR-40 materials was possible with the addition of seed crystals such as ECR-40 in the presence of diquaternary ammonium ions with the moiety containing two hydroxyl groups. From this result, we could found out the seed effects, as well as confirming that the number of hydroxyl group of organic SDAs is a crucial factor for the ECR-40 crystallization. SEM images of each ECR-40 sample indicate that the length of central alkyl chain of diquaternary ammonium ion has an influence on crystal size of ECR-40 materials. A combination of 1H, 13C, and 27Al MAS NMR spectra, and ion exchange properties clearly shows that ECR-40 materials prepared in this study are not conventional zeolites but organic SDA-bound molecular sieves with Al-OSDA direct bonding. Three types of H-ECR-40 materials exhibit lower conversion and faster deactivation than other commercial catalysts such as H-beta and H-mordenite for 1,2,4-trimethylbenzene disproportionation and cumene synthesis, respectively. These results are mainly attributed to their structural topology which is three-dimensional channel system composed of 12 and 7-rings. In addition, H-ECR-40H material with the most small crystal size shows higher conversion and slower deactivation than other H-ECR-40 materials, H-ECR40F and H-ECR-40G. This implies that their catalytic activities are affected by crystal size related with the diffusion limitations.