Abstract: The pure and Boron-doped γ-Al₂O₃ membranes were synthesized by the sol-gel method
and the thermal stability of the unsupported alumina membrane was studied by determining the pore structure change of the membranes, including
average pore size, pore volume and BET surfacearea. The experimental results show that the average pore size of the pure alumina membrane increases sharply after sintering at temperatures
higher than 1000℃. Addition of 16% Boron can considerably stabilize the pore structure of the unsupported alumina membrane.
The pore diameter for the B-doped membrane is stabilized within 13nm after sintering at 1200℃ for 5h. The substantial increase in
the pore size for the pure alumina membrane at the sintering temperatures of 1000～1200℃ is accompanied by the phase transformation
from γ-Al₂O₃ to γ-Al₂O₃. The addition of Boron can raise this phase transformation significantly and thus the thermal stability of the membranes is improved.

Key words: γ-Al₂O₃ membrane, B-doped catalysis membrane, thermal stability, microstructure, preparation