Are the Brønsted acid sites in amorphous silica–alumina bridging?
William S. Salvia, Yunpu Zhao, Puranjan Chatterjee, Wenyu Huang, Frédéric A. Perras
Abstract
Competing models exist to explain the differences in the activity of zeolites and amorphous silica-aluminas. Some postulate that silica-alumina contains dilute zeolitic bridging acid sites, while others favor a pseudo-bridging silanol model. We employed a selective isotope labeling strategy to assess the existence of Si-O(H)-Al bonds using NMR-based distance measurements.
Topics & Concepts
Bridging (networking)Amorphous silicaAmorphous solidBrønsted–Lowry acid–base theoryAmorphous silica-aluminaChemistryIsotopeZeoliteChemical engineeringCrystallographyCatalysisOrganic chemistryComputer sciencePhysicsQuantum mechanicsComputer networkEngineeringZeolite Catalysis and SynthesisAdvanced NMR Techniques and ApplicationsNMR spectroscopy and applications