Effect of Calcination Temperature on the Properties of Activated Alumina

Under the conditions of material m (AL) ∶m (CA) ∶m (ST) = 1∶0.1∶1.5, the effect of calcination temperature on the main properties of activated alumina (such as phase and pore structure) was investigated. The results are shown in Figure 1. It can be seen that when the calcination temperature is 450℃ and 550℃, the sample is basically amorphous Al2O3; but after calcined at 650℃, diffraction peaks of γ=Al2O3 begin to appear near 2θ= 25.0°, 37.5°, 45.0° and 67.0°; When the calcination temperature is 750°C, the diffraction peak of γ=Al2O3 is enhanced and tends to the crystalline state. When aluminum hydroxide or pseudo-boehmite prepared by conventional methods is calcined between 400 and 650°C, it is generally converted into γ= Al2O3^[4～6]. In the new production method, pseudo-boehmite is not generated, so amorphous Al2O3 is first generated during the calcination process.

Table 1 shows the pore structure properties of activated alumina samples calcined at different temperatures. It can be seen that as calcination temperature increases, the specific surface area of the sample gradually decreases, while the pore volume of the sample gradually increases, and the average pore diameter gradually increases.

Figure 2 shows the pore size distribution of activated alumina samples calcined at different temperatures. It can be seen that as calcination temperature increases, the pore size distribution of the sample moves to the right.