Influence of Various Sol–Gel Parameters on the Physico-Chemical Properties of Sulfuric Acid Chelated Zirconia Aerogels Dried at Ambient Pressure

This work represents the influence of various sol–gel parameters on the physico-chemical properties of sulfuric acid chelated zirconia aerogels dried at ambient pressure. The sol–gel parameters such as concentrations of precursor, chelating agent and catalyst are found to be the dominant factors which influence the physical, chemical and textural properties of the aerogels. Therefore, the influence of concentration of Zr precursor, ZrPr:H₂SO₄ molar ratio and ZrPr:H₂O molar ratio on these properties of zirconia aerogels is studied. Zirconia lacogels are formed by the hydrolysis and condensation of zirconium n-propoxide in n-propanol chelated with sulfuric acid (18.4 M) and catalyzed with deionized water. Aerogels are obtained by subsequent solvent exchange, silylation, washing and ambient pressure drying. The physico-chemical properties of as synthesized zirconia aerogels are carried out using FESEM, EDS, BET analysis and FTIR spectroscopy. The good quality zirconia aerogels are obtained using the molar ratio of ZrPr:PrOH:H₂SO₄:H₂O:HMDZ::1:2.93:1.18:1.77:0.59. They possess the density of 0.54 g cm^-3, BET surface area of 328 m² g^-1 and micropore volume of 0.028 cm³ g^-1. These aerogels can be applied as heterogeneous catalysts in many fields.