期刊
MICROPOROUS AND MESOPOROUS MATERIALS
卷 165, 期 -, 页码 134-141出版社
ELSEVIER
DOI: 10.1016/j.micromeso.2012.08.003
关键词
Sol-gel process; Acylation; Tungsten; Zirconium
WO3/ZrO2 systems were prepared by sol-gel technique using different procedures for the solvent extraction: evaporation in vacuum at room temperature (xerogel) and extraction in supercritical conditions (aerogel). Two reactions of industrial interest were investigated under mild conditions: (i) acylation of veratrole with acetic anhydride: (ii) acylation of anisole with benzoic anhydride. Several techniques were employed in order to study the influence of the synthetic parameters on texture and catalytic activity: N-2 physisorption, Fourier transformed-infrared spectroscopy. X-ray photoelectron spectroscopy, temperature programmed reduction and temperature programmed oxidation analyses. The solvent extraction strongly influences metal reducibility, surface area, pores organisation, W/Zr surface density and metallic interactions. The aerogel sample shows the best catalytic results for both conversion and yield. The supercritical extraction plays a central role especially in the recycling: by proper air activation, the aerogel sample attains the complete restoration of the catalytic activity even after three runs. (C) 2012 Elsevier Inc. All rights reserved.
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