Abstract: Poor stabilities of synthesized mesoporous sieves inhibit their applications. In present work nanosized high crystalline mineral, natural montmorillonite, was introduced into the synthetic system in order to improve the stability of mesoporous sieve. Two additional siliceous sources, Na₂SiO₃ and nano-sized white silica, were employed to widen the gallery space of montmorillonite into nano-scale. The resultant mesoporous montmorillonite was charactered by XRD, FTIR, TEM and N₂ adsorption-desorption isotherms. Moreover, the influences of milling conditions, stirring time, and type of siliceous sources on the porous structures and the hydrothermal stabilities of mesoporous montmorillonite were also discussed. The results show that intensive milling of raw materials is necessary to achieve longrange ordered mesopores in the structure. Furthermore, the multi siliceous sources make significant improvements on the hydrothermal stabilities of the samples, due to the cooperation effects between the Na₂SiO₃, white silica, and montmorillonite sheets. The highest hydrothermal stability exists in the sample synthesized from multi siliceous sources, whose original specific surface area is up to 772m²/g. After hydrothermal treatment for 10d, the sample keeps the long-range ordered mesoporous structure with specific surface area above 580m²/g.

Key words: montmorillonite, mesoporous, white silica, hydrothermal stability