Al2O3 nanofibers prepared from aluminum Di(sec-butoxide)acetoacetic ester chelate exhibits high surface area and acidity

M. A. Rodriguez-Olguin, H. Atia, M. Bosco, A. Aguirre, R. Eckelt, E. D. Asuquo, M. Vandichel*, J. G.E. Gardeniers, A. Susarrey-Arce

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Alumina (Al2O3) is a widely used material for catalysis in the chemical industry. Besides a high specific surface area, acid sites on Al2O3 play a crucial role in the chemical transformation of adsorbed molecules, which ultimately react and desorb from the catalyst. This study introduces a synthetic method based on electrospinning to produce Al2O3 nanofibers (ANFs) with acidity and porosity tuned using different aluminum precursor formulations. After electrospinning and heat treatment, the nanofibers form a non-woven network with macropores (∼4 μm). Nanofibers produced from aluminum di(sec-butoxide)acetoacetic ester chelate (ASB) show the highest total acidity of ca. 0.70 µmol/m2 determined with temperature-programmed desorption of ammonia (NH3-TPD) and BET. The nature of the acid site in ASB ANFs is studied in detail with infrared (IR) spectroscopy. Pyridine is used as a molecular probe for the identification of acid sites in ASB. Pyridine showed the presence of Lewis acid sites prominently. Density-functional theory (DFT) is conducted to understand the desorption kinetics of the adsorbed chemical species, such as ammonia (NH3) on crystalline γ-Al2O3. For our analysis, we focused on a mobile approach for chemisorbed and physisorbed NH3. The computational results are compared with NH3-TPD experiments, ultimately utilized to estimate the desorption energy and kinetic desorption parameters. The experiments are found to pair up with our simulation results. We predict that these non-woven structures will find application as a dispersion medium of metallic particles in catalysis.

Original languageEnglish
JournalJournal of catalysis
Early online date22 Nov 2021
DOIs
Publication statusE-pub ahead of print/First online - 22 Nov 2021

Keywords

  • Acidity
  • DFT
  • Electrospinning
  • Nanofibers
  • NH-TPD
  • Porous Alumina

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