Amorphous MFI-type Silicalite with the Topology of Porous Materials

We synthesized several amorphous SiO2 samples from SiO2 glass and siliceous zeolite with pressure and ball-mill treatments. We find that a pre peak observed at a k value similar to those of the （101） and （020） reflections of siliceous zeolite in the X-ray total structure factors, S（k）, of amorphous SiO2 glass prepared from siliceous zeolite. It is confirmed that amorphous SiO2 prepared from crystalline siliceous zeolite is permanently densified while amorphous SiO2 from powdered starting material and glassy SiO2 are not, and that densified siliceous zeolites retain crystalline topology even in the amorphous state.