Zirconia Aerogels: Effect of the Use of Mono- and Dicarboxylic Acids in the Sol-Gel Process on Structural Properties

摘要: Zirconia aerogels were prepared from tetra-n-butoxy zirconium(IV) using acid catalysis with different types of mono- and dicarboxylic acids ensuing supercritical drying the gels either at high temperature (578 K, HT-aerogels) or by semicontinuous extraction CO2 low (318 LT-aerogels). The resulting HT- LT-aerogels calcined in air 573 773 respectively, characterized nitrogen physisorption, X-ray diffraction, Raman spectroscopy, thermal analysis, desorption ammonia. All HT-aerogels mesoporous possessed a specific surface area between ca. 90 170 m2·g-1 after calcination K. With oxalic pore size distributions bimodal (R = 1) unimodal R 2), depending on acid-to-alkoxide ratio, R. In contrast, use acetic adipic acid, afforded distributions. Generally, crystalline part raw was made up tetragonal ZrO2 traces monoclinic zirconia, whereas higher ratio 2) phase became dominant. Calcination K had no influence distribution crystallite size. LT-aerogels, sample largest highest BET (ca. m2·g-1). amorphous Crystallization resulted formation zirconia. crystallization increased decreased.