Inuence of calcination parameters on the properties of alumina as a catalyst support

Abstract

The preparation history of Al2O3 strongly determines its properties for the application as a catalyst support. The interaction of calcination heating rate and temperature and its inuence on the structural, textural, and acidic properties of alumina were studied. Commercial-alumina was calcined at 800°C, 900°C, 1000°C, 1050°C, 1100°C, and 1150°C by 2.5°C/min, 5°C/min, and 10°C/min. By increasing temperature up to 1050°C, transition aluminas (λ, ω, and θ) were reported, but the heating rate accelerated phase transformation and changed the amount of each phase in the samples. At 1100°C and 1150°C, α-alumina appeared. Mesopore alumina with different surface areas (265-126 m2/g) was synthesized at calcination temperature from 800°C to 1050°C; when temperature reached 1100°C, the surface area decreased drastically and was around 14 m2/g. Interaction of heating rate on the temperature had minimal effect on the surface area of samples, but considerable effect on the acidic properties. The intensity of acidic properties was affected by heating rate with nonlinear proles. By increasing the heating rate, the ratio of Al cations occupied tetrahedral per octahedral sites and defect of crystal structures increased, so the surface acidity of aluminas was increased.