Formation and Acid–Base Surface Properties of Highly Dispersed η-Al2O3 Nanopowders

• Published in: Inorganic materials Vol. 54; no. 4; pp. 392 - 400
• Main Authors: Kotlovanova, N. E., Matveeva, A. N., Omarov, Sh. O., Sokolov, V. V., Akbaeva, D. N., Popkov, V. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-04-2018; Springer Nature B.V
• Subjects: Acids; Aluminum oxide; Chemical synthesis; Chemistry; Chemistry and Materials Science; Combustion products; Fourier transforms; Glycine; Heat treating; Heat treatment; Industrial Chemistry/Chemical Engineering; Infrared spectroscopy; Inorganic Chemistry; Lewis acid; Materials Science; Scanning electron microscopy; Surface properties; Thermal analysis; X-ray diffraction; aluminum oxide; adsorption; acid centers; nanocrystals; glycine–nitrate combustion
• ISSN: 0020-1685; 1608-3172
• DOI: 10.1134/S0020168518040052

Highly dispersed η-Al
2
O
3
-based nanopowders have been prepared via glycine–nitrate combustion followed by heat treatment in air. The resultant materials have been characterized by X-ray diffraction, Fourier transform IR spectroscopy, scanning electron microscopy, simultaneous thermal analysis, and other techniques. We have optimized the glycine-to-nitrate ratio (
G
/
N
= 0.2) and found heat treatment conditions for combustion products (isothermal holding at a temperature of 700°C for 6 h) that allow one to obtain single- phase nanocrystalline η-Al
2
O
3
powders with an average particle size of 5 ± 1 nm and specific surface area of 54 ± 5 m
2
/g. The acid–base surface properties of the η-Al
2
O
3
nanopowder have been analyzed using pyridine sorption–desorption processes as an example. The specific concentrations of weak, intermediate, and strong Lewis acid centers on the surface of the η-Al
2
O
3
nanocrystals have been shown to markedly exceed those on the surface of commercially available γ-Al
2
O
3
(A-64). The synthesized nanopowders can thus be used as effective supports of acid catalysts.