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

Overview

Journal J Phys Chem Lett

Publisher American Chemical Society

Specialty Chemistry

Date 2021 Nov 22

PMID 34806885

Citations 1

Authors

Zichun Wang

Kuizhi Chen

Yijiao Jiang

Julien Trebosc

Wenjie Yang

Jean-Paul Amoureux

Ivan Hung

Zhehong Gan

Alfons Baiker

Olivier Lafon

Jun Huang

Affiliations

Soon will be listed here.

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.

Citing Articles

Defects tune the acidic strength of amorphous aluminosilicates.

Verma R, Singhvi C, Venkatesh A, Polshettiwar V Nat Commun. 2024; 15(1):6899.

PMID: 39134554 PMC: 11319355. DOI: 10.1038/s41467-024-51233-9.

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