Liu Zhendong, Chokkalingam Anand, Miyagi Shoko, Yoshioka Masato, Ishikawa Tomoya, Yamada Hiroki, Ohara Koji, Tsunoji Nao, Naraki Yusuke, Sano Tsuneji, Okubo Tatsuya, Wakihara Toru
Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan.
Phys Chem Chem Phys. 2022 Feb 16;24(7):4136-4146. doi: 10.1039/d1cp03751j.
Interzeolite conversion, which refers to the synthesis of zeolites using a pre-made zeolite as the starting material, has enabled promising outcomes that could not be easily achieved by the conventional synthesis from a mixture of amorphous aluminum and silicon sources. Understanding the mechanism of interzeolite conversion is of particular interest to exploit this synthesis route for the preparation of tailor-made zeolites as well as the discovery of new structures. It has been assumed that the structural similarity between the starting zeolite and the target one is crucial to a successful interzeolite conversion. Nevertheless, an image as to how one type of zeolite evolves into another one remains unclear. In this work, a series of dealuminated FAU zeolites were created through acid leaching and employed as the starting zeolites in the synthesis of AEI zeolite under various conditions. This experimental design allowed us to create a comprehensive diagram of the interzeolite conversion from FAU to AEI as well as to figure out the key factors that enable this kinetically favourable crystallization pathway. Our results revealed different scenarios of the interzeolite conversion from FAU to AEI and pinpointed the importance of the structure of the starting FAU in determining the synthesis outcomes. A prior dealumination was proven effective to modify the structure of the initial FAU zeolite and consequently facilitate its conversion to the AEI zeolite. In addition, this strategy allowed us to directly transfer the knowledge obtained from the interzeolite conversion to a successful synthesis of the AEI zeolite from dealuminated amorphous aluminosilicate precursors. These results offer new insights to the design and fabrication of zeolites the interzeolite conversion as well as to the understandings of the crystallization mechanisms.
沸石间转化是指以预先制备的沸石为起始原料合成沸石，它已取得了一些很有前景的成果，而这些成果是传统的由无定形铝源和硅源混合物合成方法难以轻易实现的。了解沸石间转化的机制对于利用这种合成路线制备定制沸石以及发现新结构尤为重要。人们认为起始沸石与目标沸石之间的结构相似性对于成功的沸石间转化至关重要。然而，一种沸石如何演变成另一种沸石的情况仍不清楚。在这项工作中，通过酸浸法制备了一系列脱铝的FAU沸石，并将其用作在各种条件下合成AEI沸石的起始沸石。这种实验设计使我们能够构建从FAU到AEI的沸石间转化的综合图表，并找出促成这种动力学有利结晶途径的关键因素。我们的结果揭示了从FAU到AEI的沸石间转化的不同情况，并指出了起始FAU的结构在决定合成结果方面的重要性。事实证明，预先脱铝对于改变初始FAU沸石的结构并因此促进其向AEI沸石的转化是有效的。此外，这种策略使我们能够将从沸石间转化获得的知识直接应用于从脱铝的无定形硅铝酸盐前驱体成功合成AEI沸石。这些结果为沸石的设计和制造、沸石间转化以及对结晶机制的理解提供了新的见解。
