Microporous Alumino-Silicate Gels Synthesized by Sol-Gel Method

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.