ABSTRACTMicroporous alumino-silicate gels were prepared by the sol-gel method. The
Al cations were incorporated into these systems by mixing an aluminum
nitrate solution into silica water based sols under controlled pH
conditions. The micro structure as well as the form of the products are
influenced by the amount of Al additives. Al cations have significant
effects on the properties of silica sols and gels. The alumino-silicate gel
has micro porosity with surface area as high as 300 m2/g even
after calcining at 900 °C for one hour. Strong negative charge is found on
these alumino-silicate surfaces in aqueous solution indicating the Al
cations have been substituted isomorphically into the Si sites in the
framework of silica.