Thermally Induced Phase Transformation on 12-Tungstophosphoric Acid/ZrO2 Sol-Gel
Source abstract
Abstract
Zirconium (IV)-n-butoxide and tungstophosphoric acid (WP) were co-gelled at pH 3, 5 and 7 with HCl acid, C2H4O2 acid and NH4OH, respectively. Pyridine adsorption bands at 1610 and 1442 cm−1 corresponding to Lewis acidic sites were observed by FTIR spectroscopy. Acidity determined by ammonia thermodesorption shows values around 1100 μmol of NH3/g, which correspond to solids showing super acidity. It was found that the incorporation of WP to gelling zirconia delay the formation of tetragonal zirconia. Raman spectroscopy shows the stabilization of the Keggin structure on zirconia thermally treated at 400°C.
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Research context
OpenAlex topics: Polyoxometalates: Synthesis and Applications · Mesoporous Materials and Catalysis · Chemical Synthesis and Characterization
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