Preparation of Nano ZSM-5 Through Combining Bead-Milling and Porogen-Directed Recrystallization and Its Catalytic Performance for n-Heptane Cracking Reaction
ZHONG Shaocong1, SHI Huibing2, JIANG Haiying2, ZHAO Deming2, LIU Jichang1,3, ZHU Kake1
1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; 2. Shandong Chambroad Petrochemicals Company Limited, Binzhou 256500, China; 3. Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi 832003, China
Abstract：Generating nano and hierarchical zeolites provides an effective way to improve the catalytic performance. In this work, by combining destructive mechanochemical bead-milling and constructive porogen-assisted recrystallization, a new method to generate nano ZSM-5 was proposed. The parent micron-meter sized zeolites were first bead-milled into nanocrystals of low crystallinity, followed by adding polydiallydimethylammonium chloride as a porogen and growth inhibitor to proceed recrystallization, to fabricate highly crystalline nanozeolites with preserved acidity and micro-porosity. The morphology and pore structure of the obtained ZSM-5 nanozeolites were disclosed by combined X-Ray diffraction, scanning electron microscopy, N2 adsorption-desorption isotherms and solid-state magic angle spinning nuclear magnetic resonance. The acidity of the ZSM-5 zeolites was probed by ammonium temperature programmed desorption and pyridine infrared spectroscopy. The catalytic performance of the prepared ZSM-5 zeolites modified with P and La was evaluated using n-heptane catalytic cracking as a probe reaction. The results showed that the prepared nanoscale ZSM-5 was beneficial for single molecule mechanism cracking reactions, inhibited side reactions such as bimolecular cracking and hydrogen transfer. Therefore, the higher catalytic activity, higher selectivity for ethylene and propylene, lower aromatics selectivity and longer catalyst life were obtained.
ZHONG Shaocong,SHI Huibing,JIANG Haiying et al. Preparation of Nano ZSM-5 Through Combining Bead-Milling and Porogen-Directed Recrystallization and Its Catalytic Performance for n-Heptane Cracking Reaction[J]. Chemical Reaction Engineering and Technology, 2023, 39(5): 394-404.
