Preparation And Application Of Boehmite With High Surface Area And Large Pore Volume

Boehmite has been widely used in the catalyst and adsorbent due to its excellent properties such as high surface area, large pore volume and proper pore structure. Boehmite prepared with conventional methods usually has a surface area less than 350 m2/g, while boehmite with high surface area sually has small pore volume. So preparation of boehmite with both high surface area and large pore volume is a vital subject to be solved.Current methods of preparing boehmite with high surface area and large pore volume usually use aluminum alkoxides or organic additives. However, these methods not only cost a lot, but also pollute the environment.This paper adopts hydrothermal synthesis methods in the preparation of boehmite with both high surface area and large pore volume (the surface area is up to 811.3 m2/g and the pore volume is 1.93 cm3/g) by controlling the nucleation and crystal growth process of aluminium hydroxide. The boehmite was synthesized using aluminum sulfate and sodium aluminate as raw materials, without the use of any organics.The studies of the morphology and pore structure are carried on by comparing different mixing ways, crystallization temperatures, and final pH values. Boehmite doped with silicon was prepared by using aluminum sulfate, sodium aluminate and sodium silicate as raw materials and the introduction of silicon can improve both the surface area and pore volume of the boehmite. After calcined at 600℃ γ-A12O3 with the surface area of 656.8 m2/g and pore volume of 2.09 cm3/g was obtained from the boehmite with the surface area of 811.3 m2/g and pore volume of 1.93 cm3/g. Then this γ-Al2O3 was used as adsorbent to adsorb fluoride ions in water, and the saturated adsorption capacity of fluoride reaches up to 360.78 mg/g. This result is more than double the saturated adsorption capacity of fluoride ions when other alumina adsorbents were used as reported.