Influence of the Particle Sizes on the Energetic Performances of MFI-Type Zeolites

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• 作者：Ihab Kabalan ; Ismail Khay ; Habiba Nouali ; Andrey Ryzhikov ; Benedict Lebeau ; Sebastien Albrecht ; Severinne Rigolet ; Mohammad-B. Fadlallah ; Joumana Toufaily ; Taissir Hamieh ; Joel Patarin ; T. Jean Daou
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 13, 2015
• 年：2015
• 卷：119
• 期：32
• 页码：18074-18083
• 全文大小：654K
• ISSN：1932-7455

文摘

Nanoporous materials have an important role in addressing some of the major energy and environmental-related problems facing society. Herein, four MFI-type zeosils with crystallite size ranging from nanometer to micrometer were synthesized (nanosheets, nanocrystals, honeycombs, and big crystals) in order to establish a relation between the crystal size of these zeosils and their energetic performances under high-pressure intrusion鈥揺xtrusion experiments (mechanical energy storage). The intrusion鈥揺xtrusion behavior of water and concentrated LiCl aqueous solution (20 M) in these four zeosils was evaluated at room temperature. Whatever the crystal size, the 鈥淪ilicalite-1-water鈥?systems displayed a spring behavior, whereas 鈥淪ilicalite-1-LiCl aqueous solution鈥?systems moved slightly toward a shock-absorber behavior with an increase in the intrusion and extrusion pressures (273鈥?85 MPa) compared to 鈥淪ilicalite-1-water鈥?systems (88鈥?6 MPa). Therefore, in the case of the LiCl aqueous solution (20 M), the energetic performance was tripled. Compared to the big crystal sample, both the honeycomb and the nanocrystal samples showed a slight decrease of the intrusion and extrusion pressures. A decrease of the intrusion and extrusion volumes was observed in the case of nanocrystal sample compared to both big crystal and honeycomb samples, which is attributed to the noncrystallized silica regions infused within the nanocrystals. Contrary to these three samples, liquid intrusion occurred at atmospheric pressure for the nanosheet sample, which is likely due to both the presence of a high number of surface defects and the low thickness of the zeolite nanosheets (2 nm). Solid-state NMR spectroscopy and thermogravimetric analyses provided evidence on the presence of local defects on the nonintruded samples and the breaking of some siloxane bridges after the intrusion鈥揺xtrusion step.