(90h) Synthesis and Transport Property of Hierarchical Siliceous Zeolites Synthesized By Post-Synthetic Surfactant Templating
AIChE Annual Meeting
2021
2021 Annual Meeting
Materials Engineering and Sciences Division
Synthesis and Application of Inorganic Materials
Monday, November 8, 2021 - 9:45am to 10:00am
In this presentation, we studied the surfactant templating process for the formation of intracrystalline mesoporosity in a series of zeolites with different framework structure, aluminum content and defect density. This study was performed at different concentrations of NaOH in presence of cetyltrimethylammonium ammonium bromide (CTAB). Crystallinity of the samples was investigated by X-ray diffraction (XRD). Presence of mesopores was confirmed by nitrogen adsorption-desorption experiments. Transport property of the hierarchical zeolites was evaluated using Zero-length Column technique (ZLC). It was found that the surfactant templating method is more effective for zeolites with large pore structure than small-pore zeolites. The presence of Al and defects in the zeolites play a critical role in the formation mesoporosity by the surfactant-templating method. Al containing zeolites require harsher conditions for the formation of mesopore which can be attributed to the stability of Si-O-Al bonds in basic conditions. In addition, we demonstrated that the formation of mesopores in zeolites can be controlled by the introduction of structural defects, leading to a method for the synthesis of hierarchical zeolites with controllable mesopore structures.
References:
- MartÃnez-GarcÃa, J., Li, K. & Davis, M. E. Mesoporous Zeolites: Preparation, Characterization and Applications. (Wiley-VCH, 2015).
- Vattipalli, V., Qi, X., Dauenhauer, P. J. & Fan, W. Long Walks in Hierarchical Porous Materials due to Combined Surface and Configurational Diffusion. Chem. Mater. 28, 7852â7863 (2016).
- Sachse, A. et al. Development of Intracrystalline Mesoporosity in Zeolites through Surfactant-Templating. Cryst. Growth Des. 17, 4289â4305 (2017).
- Sachse, A. & GarcÃa-MartÃnez, J. Surfactant-Templating of Zeolites: From Design to Application. Chem. Mater. 29, 3827â3853 (2017).