Wang Junzhong, Zhang Qiancheng, Bai Jie, North Michael
College of Chemical Engineering, Inner Mongolia University of Technology, Hohhot 010051, China.
Green Chemistry Centre of Excellence, University of York, York YO10 5DD, U.K.
ACS Omega. 2024 Sep 9;9(38):39673-39681. doi: 10.1021/acsomega.4c04461. eCollection 2024 Sep 24.
A 4 Å zeolite prepared under the synergistic effect of intense ultrasound and a high-voltage electrostatic field had an octahedral structure rather than a conventional hexahedral structure. XPS and XRD analyses showed that the ratio of silicon to aluminum, 2θ peak position, and the corresponding crystal planes were the same as those in traditional hexahedral 4 Å zeolite, but some crystal planes were more prominent. SEM imaging showed that the octahedral zeolites had a larger particle size. Porosimetry (BET surface area and BJH analysis) showed that the octahedral zeolite had become a mesoporous zeolite, and its specific surface area increased and its pore size expanded, which was conducive to loading catalytically active materials and thus improving its catalytic performance. In this paper, the mechanism of formation of hierarchical LTA zeolite is discussed, and the octahedral hierarchical LTA zeolite is used to catalyze the epoxidation of styrene, giving very good results. It is concluded that the (600), (622), (642), and (644) crystal planes played a decisive role in the styrene epoxidation reaction, providing a realistic basis for explaining the crystal plane catalysis effect of the 4 Å zeolite. This new zeolite prepared under the synergistic effect of intense ultrasound and a high-voltage electrostatic field, being the first time to prepare the octahedral hierarchical LTA zeolite, is simple to produce, green, and environmentally friendly and has good economic development prospects compared to the use of templating agents, which not only provides ideas and simpler methods for optimizing the performance of traditional zeolites and developing new zeolites with better performance but also enhances the theoretical basis for preparing new zeolites.
在强烈超声和高压静电场协同作用下制备的4 Å沸石具有八面体结构，而非传统的六面体结构。XPS和XRD分析表明，硅铝比、2θ峰位置及相应晶面与传统六面体4 Å沸石相同，但部分晶面更为突出。SEM成像显示八面体沸石粒径更大。孔隙率测定（BET表面积和BJH分析）表明八面体沸石已成为介孔沸石，其比表面积增加且孔径扩大，有利于负载催化活性材料，从而提高其催化性能。本文讨论了分级LTA沸石的形成机理，并将八面体分级LTA沸石用于催化苯乙烯环氧化反应，取得了很好的效果。得出(600)、(622)、(642)和(644)晶面在苯乙烯环氧化反应中起决定性作用，为解释4 Å沸石的晶面催化效应提供了现实依据。这种在强烈超声和高压静电场协同作用下制备的新型沸石，首次制备出八面体分级LTA沸石，制备方法简单、绿色环保，与使用模板剂相比具有良好的经济发展前景，不仅为优化传统沸石性能和开发性能更优的新型沸石提供了思路和更简便的方法，还增强了制备新型沸石的理论基础。
