Influence of Successive Washing on Porous Structure of Pseudoboehmite

1. Introduction As we know, the structure and performance of γ-Al2O3 are determined by the pore structure of its precursor, namely, the pseudoboehmite. Some factors influencing the pore structure of the pseudoboehmite have been reported, and among them the washing process is one of the important factors because: (1) the adsorbing on the surface of the pseudoboehmite acts as a stabilizing factor for amorphous particles 1], and washing can remove the Cl- anions, thus enhanc- ing the transform…

Influence of Successive Washing on Porous Structure of Pseudoboehmite

The effect of successive washing instead of traditional intermittent washing on the porous structure of pseudoboehmite was investigated by mercury porosimetry,N2 adsorption and thermal analysis,while the stabilities of different types of crystals were investigated by X-ray diffractometer. Experimental results show that successive washing is a continuation of the aging process of intermittent washing. After a successive washing,the pore types showed no difference with the intermittent washing. During successive washing,the characteristics of the pores in the range of 2-15 nm changed only very little. However,the distributions of the pore radius for pores of 20-50 and 300-1000 nm were obviously influenced. It was shown that the volume of larger pores decreased only to a smaller extent after the successive washing,as compared with that of the intermittent washing,and the pore size was affected by the condition of the successive washing. The roles of physisorbed water,intermicellar liquid,weakly bonded water,as well as the role of stirring,have been discussed.