EFFECT OF PARTIALLY NEUTRALIZED ALUMINUM SOLUTIONS ON THE TEXTURE ANDPORE STRUCTURE OF SILICA

N-2 adsorption measurements at 77 K were performed on two types of sil ica of different porosities, and on their products obtained by soaking in partially neutralized aluminum solutions of varying R = [OH]/[Al] = 0.5-2.0 (PH 3-4). TG analysis showed that the Al taken by the mesopo rous silica was accompanied by its hydroxyls, but with the predominant ly microporous silica it was stripped of some of them, where a strong potential field in the narrow pores compensated for any charge differe nces. IR spectral analysis showed that for microporous silica the peak (due to Si-O stretching of surface OH) is located at 950 cm(-1) inste ad of approximately 970 cm(-1) in the case of mesoporous silica, which seems to result from the strong perturbation between hydroxyls at clo se range in the narrow pores. A reduction in this peak lakes place upo n Al treatment that increases with R, with the probable formation of a surface complex of the type =Si-O-Al. Uptake of Al ions produced a na rrowing of the pores, that increased with the increase in Al content. From pore structure analysis, the micropore fraction could be sorted i nto ultramicropores (less than or equal to 10 Angstrom) and supermicro pores (10-20 Angstrom). The volume of the former is almost unaffected by any change in Al content. The sizes of the supermicropores and meso pores (greater than or equal to 20 Angstrom) are crucial to the Al upt ake. Changes in pore sizes at R greater than or equal to 1.0 facilitat e the initial attack of the large Al polymeric species.