US EPA

1654688 

Journal Article 

Preparation and characterization of mesoporous gamma-Ga2O3 

Arean, CO; Bellan, AL; Mentruit, MP; Delgado, MR; Palomino, GT 

2000 

1 

Microporous and Mesoporous Materials
ISSN: 1387-1811 

40 

1-3 

35-42 

WOS:000165320200004 

Mesoporous gamma -Ga2O3 was prepared by calcination (at 773 K) of a gallia gel obtained by adding ammonia to an ethanolic solution of gallium nitrate. The corresponding powder X-ray diffraction pattern was found to be similar to that of gamma -alumina; all diffraction lines could be indexed by assuming a cubic spinel-type structure having a lattice parameter a(0) = 0.830 nm. Nitrogen adsorption-desorption at 77 K showed the material to have a BET surface area of 120 m(2) g(-1) and a most frequent pore radius of 2.1 nm. The surface chemistry was studied by FTIR spectroscopy of adsorbed carbon monoxide at liquid nitrogen temperature. Partially hydroxylated gamma -Ga2O3 gave main O-H stretching bands at 3692 and 3637 cm(-1). These hydroxyl bands were significantly perturbed by adsorbed CO, thus showing a Bronsted acid character. Lewis acidity was monitored by analyzing the C-O stretching mode of carbon monoxide adsorbed on coordinatively unsaturated Ga3+ ions; main IR absorption bands of Ga3+ CO adducts were found at 2220 and 2193 cm(-1). (C) 2000 Elsevier Science B.V. All rights reserved. 

acid sites; CO adsorption; gallium oxide; IR spectroscopy; surface chemistry