Effect of preparation conditions on the porous properties of coprecipitated Al2O3–SiO2 xerogels synthesized from aluminium nitrate nonahydrate and tetraethylorthosilicate

✍ Scribed by Kiyoshi Okada; Takahiro Tomita; Yoshikazu Kameshima; Atsuo Yasumori; Toyohiko Yano; Kenneth J.D. MacKenzie

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 573 KB
• Volume: 37
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/s1387-1811(99)00280-2

✦ Synopsis

Amorphous aluminosilicate xerogels of 9.4 mol% (15 mass%) Al 2 O 3 composition were prepared by coprecipitation under various preparation conditions to investigate their effect on the porous properties of the xerogels. The precipitates were synthesized by coprecipitation of an ethanol solution of aluminium nitrate nonahydrate (ANN ) and tetraethylorthosilicate (TEOS ) using conc. NH 4

OH as the precipitant. The xerogels were obtained by drying and calcining the precipitate at 300°C for 4 h. Various synthesis conditions were tried, such as changes in the precipitation method, concentration of total (ANN+TEOS), H 2 O/TEOS ratio, the mixing time of the ANN and TEOS solutions, and the amount of NH 4 OH added. Of these experimental parameters, the H 2 O/TEOS ratio and mixing time of the ANN and TEOS solutions exerted the greatest influence on the porous properties. The specific surface area, total pore volume and pore radius of the xerogels ranged from 123 to 455 m2 g-1, from 0.31 to 1.17 ml g-1 and from 1.8 to 20 nm, respectively. These porous properties could readily be controlled by controlling the preparation conditions of the xerogels.