Gibbsite was dehydrated in a suspension heater at a high heating velocity of an order of 10
4°C/s. One-stage dehydration products are obtained without forming boehmite and γ-Al
2O
3. The crystal structure of the products changes from χ-Al
2O
3 to α-Al
2O
3 via pseudo γ-Al
2O
3 as the temperature of heating gas rises. The product with a surface area 300m
2/g or more transforms into bayerite and pseudo boehmite by water treating for 96h at 80°C. The χ and γ-Al
2O
3 to α-Al
2O
3 phase transformation follows zero-order kinetics at the initial stage of the reaction. The dehydration products have activation energies higher than χ or γ-Al
2O
3. The rate of gibbsite to α-Al
2O
3 phase transformation in the suspension heater is much higher than that of the dehydration products in the electric furnace.
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