Details

Autor(en) / Beteiligte

• Tang, Jie
• Liu, Gui-hua
• Qi, Tian-gui
• Zhou, Qiu-sheng
• Peng, Zhi-hong
• Li, Xiao-bin

Titel

Fibrous activated alumina prepared through phase transformation using dawsonite as a template

Ist Teil von

• Journal of Central South University, 2022-04, Vol.29 (4), p.1147-1160

Ort / Verlag

Changsha: Central South University

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Fibrous activated alumina is widely applied in catalysts, adsorbents, and composite materials. This work presents a green approach in preparing the fibrous activated Al 2 O 3 with high purity and specific surface area through multistep phase transformation of aluminum-bearing substances using intermediate dawsonite as a template. Thermodynamic calculations and experimental results show that increasing the concentration of Na 2 CO 3 and (NH 4 ) 2 CO 3 is remarkably beneficial to the formation of dawsonite and ammonium aluminum carbonate hydroxide, respectively. Based on determination of dissolution and precipitation mechanism, the ultrafine granular gibbsite is converted to the uniform fibrous dawsonite with a ratio of length to diameter over 50, and the fibrous dawsonite changes into the long fibrous ammonium aluminum carbonate hydroxide with a ratio of length to diameter is about 80 in above 70 g/L (NH 4 ) 2 CO 3 solution. Furthermore, the activated alumina remains fibrous morphology after roasting ammonium aluminum carbonate hydroxide at a slow heating rate, plentiful open mesopore and weak aggregation of particles, which contributes to the high specific surface area of 159.37 m 2 /g at 1273 K for the activated alumina. The complete transformation of dawsonite to ammonium aluminum carbonate hydroxide and high specific surface area contribute to the purity of the activated fibrous alumina above 99.9% with low Na and Fe content.