The Preparation And Characterization Of Zr/Al-Pillared Montmorillonite

Ca-montmorillonite was from Xinyang, Henan province and was sodium-modified as raw material. Zr/Al-pillaring agent was synthesized and the Zr/Al-pillared montmorillonite was prepared by ion-exchange. X-ray diffraction patterns analysis, Fourier-transform infrared spectrometer analysis, Chemical analysis and specific surface area analysis were applied to study the properties of Zr/Al-pillared montmorillonite. At the same time, the crystal structure of hydroxyl-zirconium and hydroxyl-aluminum oligocation has been discussed.The basal spacing d(001) value was considered as standard to judge the pillaring effect. The better conditions of preparation were selected that the molar ratio of Zr4+ and Al3+ was 1:6, the volume of 0.4 mol/L NaOH was 70mL, the ratio of metal cation and montmorillonite was 10mmol/g, the reactive temperature was 60℃, the aging time of pillaring agent and pillaring product are both a day. The research results showed that the pillaring agent inserted into the interlamination of montmorillonite and was bonding with the Si-O of the interlamination of montmorillonite, the d(001) value of Zr/Al pillared montmorillonite became from 1.2726nm to 1.9278nm, and the BET specific surface area increased from 91.76m2/g to 177.9 m2/g but the average pore diameter decreased to 2.025nm, it indicated that Zr/Al pillared montmorillonite had larger specific surface area and smaller average pore diameter. The results showed the Zr/Al pillared montmorillonite was a kind of useful adsorption and catalysis materials.The thermal stability of the zirconia-and alumina-pillared montmorillonite has been investigated. The results showed that the Zr/Al pillared montmorillonite was still presented as meso-microporous properties.when calcined at 500℃, the Zr/Al pillared montmorillonite still had excellent stabilily. After the thermal treatment temperature reached 600℃, the bond of the Al(Zr)-OH disappeared, it was resulted that the hydroxyl-zirconium and hydroxyl-aluminum oligocation dehydrated completely. At the same time, the peak intensity became weaker and the specific surface area decreased more, it showed that crystal layer of the Zr/Al pillared montmorillonite was destroyed.The study on the structure of Zr/Al pillaring agent showed that the Zr4+ and Al3+ in the Zr/Al pillaring agent may partially substituted in the central of coordination and it mainly existed that Zr4+ in the Zr/Al pillaring agent partially substituted the Al3+ in [AlO4Al12(OH)24(OH2)12]7+ in the form of octahedron.