Loading...
Al2O3 nanofibers prepared from aluminum Di(sec-butoxide)acetoacetic ester chelate exhibits high surface area and acidity
Date
2021
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.
Supervisor
Description
Publisher
Elsevier
Citation
Journal of Catalysis, 2022, 405, pp. 520-533
Collections
Files
Funding code
Funding Information
The authors thank Stephan Bartling (Leibniz Institute for Catalysis), Regina Lange and Ingo Barke (University of Rostock, Institute of Physics), Frank Morssinkhof (Membrane Science & Technology Cluster, University of Twente), and Mark Smithers (MESA + Institute, University of Twente) for their support. M.V. wishes to acknowledge the Irish Centre for High-End Computing (ICHEC) for the provision of computational facilities and support. The research leading to the results in this report has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant agreement No. 742004).