The Preparation And Characterization Of Al-Pillared Montmorillonite

The pillared montmorillonites have been proved to be one of the most interesting materials at home and abroad. They are widely used in the fields such as catalysis, catalytic supports, selective sorbent, molecular screen, film, electrochemistry, optical element for their good properties of large BET surface area, high pore volume, tunable pore size(from microspore to mesopore), high thermal stability, strong surface acidity active and large surface activity.The paper was aimed to study the influencing factors of materials in the preparation process. In this paper, A1-PM, Cr-PM were prepared by hydrolytic decomposition method. Composition, structure and properties of the pillared montmorillonite were studied with the means of spectrophotometry, XRD, DTA, FT-IR, N2-absorption-desorption. The research results suggest that A1-PM, Cr-PM prepared was very successful using NaCa-mont as staring materials. The montmorillonite pillared using positive direction titration and reverse direction titration have theirs individual merits and demerits. The optimization conditions of preparation by the hydrolytic decomposition method are OH -/ A13+ =2.6; Al/montmorillonite = 5mmol/g; suspending liquid ofmontmorillonite =5%; in order to suspending liquid delamination, we are stirring half an hour in magnetic stirring apparatus or handling five minutes in ultrasonic baths. Prepared slurry were drying in room-temperature. The surface area of Al-PM is in the range of 145.64-295.47m2/g, 3-6times larger than one of primary sample, microspore sizes of Al-PM are dominated in the range of 0.7 - 0.9nm. Which have been believed to be the interlamination coarctation split of two-dimension pore canal. Mesopore sizes of its are focus in the middle of 3.4-3.7nm, in addition contain some macropore of 10-30nm, which are believed to be mesopore or macropore of house-of-cards-like formation end-face, end-end contact. In the whole of pore size distribution, micropore quantities far off preponderate over mesopore quantities and macrospore quantities is very little, which is commonly overlooked.Deprivation process boundary point of interlaminar planar water and structure hydroxyl group of OH-Al-PM have became extraordinary ambiguity, Entirely weight loss have not finished until 750 C, Temperature of structure decomposition in Al-PM are generality dominated by 850 C, thermal stability visible is very good. With temperature stepping up, interlamination pillaredagent of OH-Al-PM begin to deprivation planar water at 105 C , then gradualloss its structure water and hydroxyl group and formation Al-polyoxoionic which build-up stationary covalent bond with montmorillonite interlamination ionic.Al-PM that were heated there hours at 500 C can not see visibility absorption spectrum at 906 cm'1 and 835 cm"1 which indicate OH group pendulum motion among A1A1OH, Fe3+AlOH and MgAlOH of octahedron sheet, It indicate structure of octahedron sheet have shift. We deduction pillaredagent of OH-Al-PM in the course of heated handling may react with OH group of octahedron sheet and formation stable covalent bond of AlsheetIV-0-AlpillarVI from OH group pendulum motion weaken.