Yoshioka Tatsushi, Iyoki Kenta, Hotta Yuusuke, Kamimura Yoshihiro, Yamada Hiroki, Han Qiao, Kato Takeharu, Fisher Craig A J, Liu Zhendong, Ohnishi Ryohji, Yanaba Yutaka, Ohara Koji, Sasaki Yukichi, Endo Akira, Takewaki Takahiko, 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.
Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan.
Sci Adv. 2022 Jun 24;8(25):eabo3093. doi: 10.1126/sciadv.abo3093. Epub 2022 Jun 22.
Small-pore zeolites are gaining increasing attention owing to their superior catalytic performance. Despite being critical for the catalytic activity and lifetime, postsynthetic tuning of bulk Si/Al ratios of small-pore zeolites has not been achieved with well-preserved crystallinity because of the limited mass transfer of aluminum species through narrow micropores. Here, we demonstrate a postsynthetic approach to tune the composition of small-pore zeolites using a previously unexplored strategy named pore-opening migration process (POMP). Acid treatment assisted by stabilization of the zeolite framework by organic cations in pores is proven to be successful for the removal of Al species from zeolite via POMP. Furthermore, the dealuminated AFX zeolite is treated via defect healing, which yields superior hydrothermal stability against severe steam conditions. Our findings could facilitate industrial applications of small-pore zeolites via aluminum content control and defect healing and could elucidate the structural reconstruction and arrangement processes for inorganic microporous materials.
小孔沸石因其优异的催化性能而受到越来越多的关注。尽管对于催化活性和寿命至关重要，但由于铝物种在狭窄微孔中的传质受限，小孔沸石的整体硅铝比的合成后调节尚未在保持良好结晶度的情况下实现。在此，我们展示了一种合成后方法，使用一种名为开孔迁移过程（POMP）的先前未探索的策略来调节小孔沸石的组成。事实证明，通过孔内有机阳离子对沸石骨架的稳定作用辅助的酸处理，能够成功地通过POMP从沸石中去除铝物种。此外，脱铝的AFX沸石通过缺陷修复进行处理，这使其在苛刻的蒸汽条件下具有优异的水热稳定性。我们的发现可以通过控制铝含量和缺陷修复促进小孔沸石的工业应用，并可以阐明无机微孔材料的结构重建和排列过程。
