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Induced active sites by adsorbate in zeotype materials

DOI: 10.1021/jacs.1c03166 DOI Help

Authors: Guangchao Li (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences; University of Oxford; University of Chinese Academy of Sciences) , Christopher Foo (University of Oxford; Diamond Light Source) , Xianfeng Yi (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences) , Wei Chen (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences) , Pu Zhao (University of Oxford) , Pan Gao (Dalian Institute of Chemical Physics, Chinese Academy of Sciences) , Tatchamapan Yoskamtorn (University of Oxford) , Yao Xiao (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences; University of Chinese Academy of Sciences) , Sarah Day (Diamond Light Source) , Chiu C. Tang (Diamond Light Source) , Guangjin Hou (Dalian Institute of Chemical Physics, Chinese Academy of Sciences) , Anmin Zheng (Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences) , Shik Chi Edman Tsang (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society , VOL 221

State: Published (Approved)
Published: June 2021

Abstract: There has been a long debate on how and where active sites are created for molecular adsorption and catalysis in zeolites, which underpin many important industrial applications. It is well accepted that Lewis acidic sites (LASs) and basic sites (LBSs) as active sites in pristine zeolites are generally believed to be the extra-framework Al species and residue anion (OH–) species formed at fixed crystallographic positions after their synthesis. However, the dynamic interactions of adsorbates/reactants with pristine zeotype materials to “create” sites during real conditions remain largely unexplored. Herein, direct experimental observation of the establishment of induced active sites in silicoaluminophosphate (SAPO) by an adsorbate is for the first time made, which contradicts the traditional view of the fixed active sites in zeotype materials. Evidence shows that an induced frustrated Lewis pair (FLP, three-coordinated framework Al as LAS and SiO (H) as LBS) can be transiently favored for heterolytic molecular binding/reactions of competitive polar adsorbates due to their ineffective orbital overlap in the rigid framework. High-resolution magic-angle-spinning solid-state NMR, synchrotron X-ray diffraction, neutron powder diffraction, in situ diffuse reflectance infrared Fourier transform spectroscopy, and ab initio molecular dynamics demonstrate the transformation of a typical Brønsted acid site (Al(OH)Si) in SAPO zeolites to new induced FLP structure for hetereolytic binding upon adsorption of a strong polar adsorbate. Our unprecedented finding opens up a new avenue to understanding the dynamic establishment of active sites for adsorption or chemical reactions under molecular bombardment of zeolitic structures.

Journal Keywords: Frustrated Lewis pairs; Alcohols; Adsorption; Zeolites; Ketones

Subject Areas: Materials, Chemistry


Instruments: I11-High Resolution Powder Diffraction

Other Facilities: GDDP at China Spallation Neutron Source

Added On: 07/06/2021 09:29

Discipline Tags:

Catalysis Physical Chemistry Zeolites Materials Science Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction