Related Experiment Video
Updated: Feb 2, 2026

Author Spotlight: Simulation and Analysis of the Temperature Rise of Ring Main Unit Equipment
Published on: July 5, 2024
Comparative study of the strongest solid Lewis acids known: ACF and HS-AlF3
Beatriz Calvo1, Clara Patricia Marshall, Thoralf Krahl
1Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, D-12489 Berlin, Germany. erhard.kemnitz@chemie.hu-berlin.de thomas.braun@cms.hu-berlin.de.
Abstract:
Aluminium chlorofluoride (ACF) and high-surface aluminium fluoride (HS-AlF3) were analyzed by a set of characterization methods to assess their acidic properties: NH3-TPD, CO adsorption followed by DRIFTS, CD3CN-PAS-FTIR and MAS NMR spectroscopy after 15N-pyridine adsorption. Both catalysts contain very strong and medium-strong Lewis acid sites as confirmed by CO adsorption, in which small differences arise from the morphological properties of each catalyst, with ACF being microporous and HS-AlF3 mesoporous. Shifts of the CO vibration band of up to 77 cm-1 were observed, which account for very strong Lewis acid sites. In addition, very strong Lewis acid sites could be identified by CD3CN-PAS for both catalysts, exhibiting a shift of 95 cm-1 from free nitrile, the highest ever reported for a solid Lewis acid.
Related Concept Videos
Lewis Acids and Bases
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
Lewis Acids and Bases
Lewis Symbols and the Octet Rule
Covalent Bonding and Lewis Structures
Lewis Structures of Molecular Compounds and Polyatomic Ions
Comparative Excretory Systems

