Sol-gel preparation of AlPO4–SiO2 glasses with high surface mesoporous structure

Abstract

Transparent and colorless amorphous silica–aluminum phosphate gels and glasses along the composition line, xAlPO4–(1−x)SiO2 were prepared via the sol-gel route using tetraethylorthosilicate (TEOS), aluminum lactate, and ammonium dihydrogen phosphate as precursors. The glass-forming range was significantly extended, compared with that accessible by previously reported routes. After calcination at 600 °C, the amorphous AlPO4–SiO2 material exhibits an attractive mesoporous structure with surface areas as high as 582 m2 g−1. With increasing gel-processing and conversion temperature, the average degree of P/Al connectivity increases, while the Q3 silicon units present in the gels are gradually converted to Q4 units. After sample calcination above 600 °C for 8 h, the NMR results indicate that the structure of the prepared materials is composed of AlPO4- and SiO2-nanodomains.