Zi Wenwen, Cai Xianshu, Jiao Feng, Du Hongbin
State Key Laboratory of Coordination Chemistry, School of Chemistry, and Chemical Engineering, Nanjing University, 210023, Nanjing, P. R. China.
Chemistry. 2020 Dec 18;26(71):17143-17148. doi: 10.1002/chem.202003183. Epub 2020 Nov 19.
Pure silica zeolites possessing uniform micropores, large surface area and high thermal and chemical stability have been widely studied and used in the fields of fine chemicals and oil industry. The incorporation of aluminium into the framework of silica zeolites changes their properties, making them more industrially useful as adsorbents and catalysts. Herein, we report the synthesis and characterization of an extra-large-pore aluminosilicate zeolite NUD-6 with a 16-membered-ring pore channel. Aluminium was directly incorporated into the zeolite NUD-6 framework, as confirmed by Al MAS NMR studies and ammonia temperature-programmed desorption probes. Al-NUD-6 was not stable when heated at 550 °C to remove the organic templates. However, the organic templates in Al-NUD-6 could be removed by oxidation in nitric acid at room temperature. The obtained Al-NUD-6H retained the crystalline structure and possessed both micropores and mesopores despite the occurrence of severe structural distortions due to the presence of the corner-sharing Q Si O units. The incorporation of aluminium resulted in both medium and strong acid sites in Al-NUD-6H, and could facilitate its use in adsorption and catalysis.
具有均匀微孔、大表面积以及高热稳定性和化学稳定性的纯硅沸石已在精细化工和石油工业领域得到广泛研究和应用。将铝引入硅沸石骨架会改变其性质，使其作为吸附剂和催化剂在工业上更具实用性。在此，我们报道了一种具有16元环孔道的超大孔铝硅酸盐沸石NUD - 6的合成与表征。通过铝的固体核磁共振（Al MAS NMR）研究和氨程序升温脱附探针证实，铝被直接引入到沸石NUD - 6骨架中。当在550°C加热以去除有机模板时，Al - NUD - 6不稳定。然而，Al - NUD - 6中的有机模板可在室温下通过硝酸氧化去除。尽管由于存在角共享Q Si O单元而出现严重的结构畸变，但所得的Al - NUD - 6H保留了晶体结构，并且同时具有微孔和介孔。铝的引入导致Al - NUD - 6H中同时存在中强酸位点和强酸位点，这有利于其在吸附和催化方面的应用。
