Thermal Alteration in Adsorption Sites over SAPO‐34 Zeolite. (12th May 2022)

• Record Type: Journal Article
• Authors: Li, Guangchao; Yoskamtorn, Tatchamapan; Chen, Wei; Foo, Christopher; Zheng, Jianwei; Tang, Chiu; Day, Sarah; Zheng, Anmin; Li, Molly Meng‐Jung; Tsang, Shik Chi Edman
• Is Part Of: Angewandte Chemie. Volume 134:Number 27(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-12
• Subjects: Active Sites -- Frustrated Lewis Pair -- Synchrotron X-Ray Diffraction -- Solid-State Nuclear Magnetic Resonance -- Zeolites; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202204500
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Zeolites have found tremendous applications in the chemical industry. However, the dynamic nature of their active sites under the flow of adsorbate molecules for adsorption and catalysis is unclear, especially in operando conditions, which could be different from the as‐synthesized structures. In the present study, we report a structural transformation of the adsorptive active sites in SAPO‐34 zeolite by using acetone as a probe molecule under various temperatures. The combination of solid‐state nuclear magnetic resonance, in situ variable‐temperature synchrotron X‐ray diffraction, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy allow a clear identification and quantification that the chemisorption of acetone can convert the classical Brønsted acid site adsorption mode to an induced Frustrated Lewis Pairs adsorption mode at increasing temperatures. Such facile conversion is also supported by the calculations of ab‐initio molecular‐dynamics simulations. This work sheds new light on the importance of the dynamic structural alteration of active sites in zeolites with adsorbates at elevated temperatures. Abstract : To better identify the structure of the active sites in zeolites under real reaction conditions, we demonstrate that the adsorption mode of acetone over classical Brønsted acid sites (BAS) can be thermally converted into the induced Frustrated Lewis Pair (FLP) adsorption mode in SAPO‐34 zeolite.