Local order in depolymerized silicate lattices.

In glycerol, near 200 degrees C, the silicate networks of mesoporous silicates and zeolites undergo a deep depolymerization process. In a few hours, depending on the initial concentration of the solid in glycerol and on the temperature, amorphous gels are obtained. In these gels, a fraction of the Si-O-Si bonds are transformed into Si-O-C. The constitutional aluminum remains bound to the silica network in the gel. The short range ordering is maintained to some extent: the size of the smallest structural unit in gels obtained from zeolites is in the range of the cubic nanometer, nm3.