Liu Chuang, Qi Guodong, Gong Yudan, Wang Darui, Fu Wenhua, Liu Fang, Xu Jun, Liu Dianhua, Wang Zhendong, Yang Weimin
School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, SINOPEC Shanghai Research Institute of Petrochemical Technology Co., Ltd., Shanghai 201208, China.
Chem Bio Eng. 2025 Apr 10;2(6):358-369. doi: 10.1021/cbe.5c00016. eCollection 2025 Jun 26.
MWW zeolites exhibit a distinctive combination of both 10- and 12- features, making them highly versatile in catalytic applications. When dealing with bulk molecules, the acid sites located on the external surface often serve as the primary active sites, and thus, the distribution of Al sites significantly impacts the active acidity and catalytic performance. In this study, a precise modulation of Al distribution within MWW zeolites was investigated using commercially available N,N,N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) and cyclohexylamine as organic structure-directing agents (OSDAs). The effects of both OSDAs, along with the synthesis temperature, duration and Na, on the formation of the MWW framework were systematically examined. Advanced solid-state NMR characterization addressed the correlation between Al and organic species. The presence of TMAdaOH showed significant influence on the distributions of cyclohexylamine and T Al sites as well as the benzene transport rate, resulting in MWW zeolites with enriched external surface accessible active acid sites. Owing to these properties, the MWW zeolites exhibited superior catalytic performance compared to conventional MCM-22 zeolites in the cracking of TiPB and alkylation of benzene with cyclohexene. This study highlights the successful synthesis of MWW zeolites using small amounts of low-toxicity OSDAs, offering a scalable and economical approach for the production of zeolites with enhanced catalytic properties for industrial applications.
MWW 沸石具有独特的 10 元环和 12 元环结构特征组合，使其在催化应用中具有高度的通用性。在处理大分子时，位于外表面的酸性位点通常作为主要活性位点，因此，铝位点的分布对活性酸度和催化性能有显著影响。在本研究中，使用市售的 N,N,N-三甲基-1-金刚烷基氢氧化铵（TMAdaOH）和环己胺作为有机结构导向剂（OSDA），研究了 MWW 沸石中铝分布的精确调控。系统地考察了两种 OSDA 以及合成温度、时间和钠对 MWW 骨架形成的影响。先进的固态核磁共振表征揭示了铝与有机物种之间的相关性。TMAdaOH 的存在对环己胺和 T 型铝位点的分布以及苯的传输速率有显著影响，从而得到外表面可及活性酸位点富集的 MWW 沸石。由于这些特性，MWW 沸石在 TiPB 裂解和苯与环己烯烷基化反应中表现出优于传统 MCM-22 沸石的催化性能。本研究突出了使用少量低毒 OSDA 成功合成 MWW 沸石，为工业应用生产具有增强催化性能的沸石提供了一种可扩展且经济的方法。
