In uence of calcination parameters on the properties of alumina as a catalyst support

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 in uence on the structural, textural, and acidic properties of alumina were studied. Commercial -alumina was calcined at 800C, 900C, 1000C, 1050C, 1100C, and 1150C by 2.5C/min, 5C/min, and 10C/min. By increasing temperature up to 1050C, transition aluminas ( , , and ) were reported, but the heating rate accelerated phase transformation and changed the amount of each phase in the samples. At 1100C and 1150C, -alumina appeared. Mesopore alumina with dierent surface areas (265-126 m2/g) was synthesized at calcination temperature from 800C to 1050C; when temperature reached 1100C, the surface area decreased drastically and was around 14 m2/g. Interaction of heating rate on the temperature had minimal eect on the surface area of samples, but considerable eect on the acidic properties. The intensity of acidic properties was aected by heating rate with nonlinear proles. 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.