Preparation of B-doped γ-Al_2O_3 Catalysis Membrane and the Improvement of Its Thermal Stability

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.