武汉理工大学阳晓宇团队报道了高催化活性ZSM-5分子筛的定向输运。相关研究成果于2024年10月24日发表在国际顶尖学术期刊《美国化学会杂志》。

沸石是技术上最重要的结晶微孔材料，因其卓越的催化性能和吸附能力而成为化学工程不可或缺的基石。许多研究表明，沸石的分级工程可以最大限度地提高可获得的活性位点并改善传质，从而显著降低内部扩散极限，以实现所需的性能。然而，以一种方便的方式构建具有有序排列和尺寸可控子结构的多级沸石极具挑战性。

该文中，研究人员开发了一种简单的方法，使用两种常见的结构导向剂，氢氧化四丙基铵（TPAOH）和氢氧化四乙基铵（TEAOH），合成具有可控尺寸的a轴取向亚结构的分级取向ZSM-5（Hie-ZSM-5）晶体。通过改变Si/Al比（40-120），可以调节子结构尺寸（α）在10-60nm范围内的控制以及相应的相似性（r=α/β，其中β是Hie-ZSM-5的尺寸）在0.004-0.033范围内。

使用含时XRD、SEM、TEM和固态魔角自旋NMR（13C、27Al、29Si）方法对整个结晶过程进行系统研究，从而能够构建Hie-ZSM-5生成的固体机制。最重要的是，Hie-ZSM-5独特结构中的定向传输，有效地增强了质量扩散以及催化活性和稳定性。

研究结果提高了人们对沸石结晶过程的理解，并为合理设计分级沸石提供了新的方法。

附：英文原文

Title: Directional Transport in Hierarchically Aligned ZSM-5 Zeolites with High Catalytic Activity

Author: Bojun Zeng, Siming Wu, Mingbin Gao, Ge Tian, Liying Wang, Zhiwen Yin, Zhiyi Hu, Wen Zhang, Ganggang Chang, Mao Ye, Christoph Janiak, Osamu Terasaki, Xiaoyu Yang

Issue&Volume: October 24, 2024

Abstract: Zeolites, the most technically important crystalline microporous materials, are indispensable cornerstones of chemical engineering because of their remarkable catalytic properties and adsorption capabilities. Numerous studies have demonstrated that the hierarchical engineering of zeolites can maximize accessible active sites and improve mass transport, which significantly decreases the internal diffusion limits to achieve the desired performance. However, the construction of hierarchical zeolites with ordered alignments and size-controlled substructures in a convenient way is highly challenging. Herein, we develop a facile procedure using two common structure-directing agents, tetrapropylammonium hydroxide (TPAOH) and tetraethylammonium hydroxide (TEAOH), to synthesize hierarchically aligned ZSM-5 (Hie-ZSM-5) crystals with a-axis alignment substructures of controllable size. The control of the substructure size (α) in the range of 10–60 nm and the corresponding similarity (r = α/β, where β is the size of Hie-ZSM-5) ranging from 0.004 to 0.033 can be tuned by varying the Si/Al ratios (40–120). A systematic investigation of the overall crystallization process, using time-dependent XRD, SEM, TEM, and solid-state magic-angle spinning NMR (13C, 27Al, 29Si) methods, enable us to construct a solid mechanism for the generation of Hie-ZSM-5. Most importantly, directional transport in the unique structures of Hie-ZSM-5 efficiently enhances mass diffusion, as well as catalytic activity and stability. These findings improve our understanding of the zeolite crystallization process and inspire novel methods for the rational design of hierarchical zeolites.

DOI: 10.1021/jacs.4c09483

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c09483