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Revealing Brønsted Acidic Bridging SiOHAl Groups on Amorphous Silica-Alumina by Ultrahigh Field Solid-State NMR. | LitMetric

Revealing Brønsted Acidic Bridging SiOHAl Groups on Amorphous Silica-Alumina by Ultrahigh Field Solid-State NMR.

J Phys Chem Lett

Laboratory for Catalysis Engineering, School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia.

Published: December 2021

AI Article Synopsis

Article Abstract

Amorphous silica-aluminas (ASAs) are important acidic catalysts and supports for many industrially essential and sustainable processes. The identification of surface acid sites with their local structures on ASAs is of critical importance for tuning their catalytic properties but still remains a great challenge and is under debate. Here, ultrahigh magnetic field (35.2 T) Al-{H} D-HMQC (dipolar-mediated heteronuclear multiple-quantum correlation) two-dimensional NMR experiments demonstrate two types of Brønsted acid sites in ASA catalysts. In addition to the known pseudobridging silanol acid sites, the use of ultrahigh field NMR provides the first direct experimental evidence for the existence of bridging silanol (BS: SiOHAl) acid sites in ASAs, which has been hotly debated in the past few decades. This discovery provides new opportunities for scientists and engineers to develop and apply ASAs in various reaction processes due to the significance of BS in chemical and fuel productions based on its strong Brønsted acidity.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9162276PMC
http://dx.doi.org/10.1021/acs.jpclett.1c02975DOI Listing

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