Monolithic TiO 2 aerogels have been prepared from titanium n butoxide by sol gel process and supercritical drying technique, and the structural properties of the aerogel samples have been characterized by means of SEM...Monolithic TiO 2 aerogels have been prepared from titanium n butoxide by sol gel process and supercritical drying technique, and the structural properties of the aerogel samples have been characterized by means of SEM, TEM, XRD, IR, BET and pore distribution analysis. The results indicated that the optimum condition for preparing monolithic TiO 2 aerogels was n [Ti(OC 4H 9) 4]∶ n (C 2H 5OH)∶ n (H 2O)∶ n (HNO 3) =1∶18.3∶3.75∶0.14. The final aerogels which consist of colloidal particles with diameters of about 5 nm were found to be with coherent uniform size and low density solid inorganic materials with porosity of about 90%, and contained mesopore in the range of 10-20 nm. The monolithic TiO 2 aerogels were of the pure amorphous form at room temperature, which would be converted into anatase and then into rutile by increasing the temperature of heat treatment.展开更多
Zirconia alumina composite was prepared as rigid microspheres by means of a sol gel process. Scan electron micrograph, electron spectroscopy, nitrogen adsorption, and potentiometric titration were used to characterize...Zirconia alumina composite was prepared as rigid microspheres by means of a sol gel process. Scan electron micrograph, electron spectroscopy, nitrogen adsorption, and potentiometric titration were used to characterize the zirconia alumina composite before and after acid etching. After the acid etching, the specific surface area of the zirconia alumina composite is about five times larger than that before acid etching; the molar ratio of Zr/Al and the acidity also increases, while the pore size decreases. The normal phase chromatographic performance of the zirconia alumina composite before and after acid etching was studied by using dichloromethane/cyclohexane, chloroform/cyclohexane, ethanol/cyclohexane as mobile phases. After the acid etching the zirconia alumina composite exhibited a higher column efficiency and different separation selectivity as compared with that before the acid etching. Basic compounds have a greater retention on the composite after the acid etching.展开更多
文摘Monolithic TiO 2 aerogels have been prepared from titanium n butoxide by sol gel process and supercritical drying technique, and the structural properties of the aerogel samples have been characterized by means of SEM, TEM, XRD, IR, BET and pore distribution analysis. The results indicated that the optimum condition for preparing monolithic TiO 2 aerogels was n [Ti(OC 4H 9) 4]∶ n (C 2H 5OH)∶ n (H 2O)∶ n (HNO 3) =1∶18.3∶3.75∶0.14. The final aerogels which consist of colloidal particles with diameters of about 5 nm were found to be with coherent uniform size and low density solid inorganic materials with porosity of about 90%, and contained mesopore in the range of 10-20 nm. The monolithic TiO 2 aerogels were of the pure amorphous form at room temperature, which would be converted into anatase and then into rutile by increasing the temperature of heat treatment.
文摘Zirconia alumina composite was prepared as rigid microspheres by means of a sol gel process. Scan electron micrograph, electron spectroscopy, nitrogen adsorption, and potentiometric titration were used to characterize the zirconia alumina composite before and after acid etching. After the acid etching, the specific surface area of the zirconia alumina composite is about five times larger than that before acid etching; the molar ratio of Zr/Al and the acidity also increases, while the pore size decreases. The normal phase chromatographic performance of the zirconia alumina composite before and after acid etching was studied by using dichloromethane/cyclohexane, chloroform/cyclohexane, ethanol/cyclohexane as mobile phases. After the acid etching the zirconia alumina composite exhibited a higher column efficiency and different separation selectivity as compared with that before the acid etching. Basic compounds have a greater retention on the composite after the acid etching.
