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Integrated Theoretical and Empirical Studies for Probing Substrate–Framework Interactions in Hierarchical Catalysts
Author(s) -
Chapman Stephanie,
O'Malley Alexander J.,
Miletto Ivana,
Carravetta Marina,
Cox Paul,
Gianotti Enrica,
Marchese Leonardo,
Parker Stewart F.,
Raja Robert
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901188
Subject(s) - substrate (aquarium) , catalysis , computer science , nanotechnology , materials science , chemistry , ecology , biology , organic chemistry
Soft templating with siliceous surfactant is an established protocol for the synthesis of hierarchically porous silicoaluminophosphates (HP SAPOs) with improved mass transport properties. Motivated by the enhanced performance of HP SAPOs in the Beckmann rearrangement of cyclohexanone oxime to the nylon 6 precursor ϵ‐caprolactam, an integrated theoretical and empirical study was carried out to investigate the catalytic potential of the siliceous mesopore network. Inelastic neutron scattering (INS) studies, in particular, provided unique insight into the substrate‐framework interactions in HP (Si)AlPOs and allowed reactive species to be studied independent of the catalyst matrix. The spectroscopic (INS, FTIR spectroscopy, MAS NMR spectroscopy) and computational analyses revealed that in the organosilane‐templated SAPO, the interconnectivity of micro‐ and mesopores permits cooperativity between their respective silanol and Brønsted acid sites that facilitates the protonation of cyclohexanone oxime in a physical mixture at ambient temperature.