Investigation of the effect of lanthanum oxide on the thermal stability of alumina aerogel

Foreign element doping and thermal stability of alumina aerogels

“…Although high-surface area alumina aerogels can be prepared by this epoxide-assisted strategy, the aerogels tend to lose their specific surface area (SSA) rapidly owing to phase transitions at elevated temperatures. Baumann et al 11 found that the SSA of the alumina aerogel dropped from 709 to 289 m 2 /g after heat treatment at 800 • C. Yamuna et al 15 reported that the synthesized alumina aerogels (from aluminum nitrate) transformed to α-Al 2 O 3 accompanied with a sharp reduction of SSA to less than 50 m 2 /g after 1250 • C calcination for 3 h, as is similar to the results obtained by Lermontov et al 16 Sun et al 17 prepared the alumina aerogel which lost most of its SSA at 1200 • C (9 m 2 /g). Foreign elements have been introduced to improve the thermal stability of alumina aerogels.…”

“…20 The prepared silica modified alumina xerogels could maintain an SSA of 360 m 2 /g at 1000 • C. Besides the silicon, lanthanum doping was also found to be helpful for the thermal stability of alumina aerogels. 17,21 These doped alumina aerogels generally remain SSA of less than 100 m 2 /g at 1200 • C. The high-temperature maintenance of SSA and pore volume for these alumina aerogels need to be further improved. In addition, for optimization purpose, it is important to understand how these dopants distribute and work in alumina aerogels.…”