铬铝基柱撑蒙脱石的制备与孔道结构

Preparation and channel structure of Al-Cr-pillared montmorillonite

以钠基蒙脱石为原料,采用取代法合成铬铝柱化剂,并用湿法工艺制备铬铝基柱撑蒙脱石,研究不同Cr与Al物质的量比和pH对柱撑蒙脱石制备的影响。研究结果表明:当Cr离子与Al离子物质的量比为2:1、加入100mL浓度为0.4mol/L NaOH时,可得到(001)层间距达2.0535nm的铬铝基柱撑蒙脱石,铬铝二元聚合羟基阳离子与钠基蒙脱石之间发生离子交换反应,进入膨胀的蒙脱石层间;铬铝柱撑蒙脱石的基本结构在离子交换过程中并没有发生改变,且发现铬氧八面体,但未发现铬氧四面体,铬离子倾向于以铬氧八面体的形式进入铬铝基柱撑蒙脱石层间;铬铝基柱撑蒙脱石的比表面积为170.4m2/g,孔容为0.1841cm3/g,介孔平均孔径为3.840nm,说明铬铝基柱撑蒙脱石比钠基柱撑蒙脱石、铝基柱撑蒙脱石和铬基柱撑蒙脱石具有较大的比表面积、较大的微孔和较小的介孔,铬铝柱撑蒙脱石是一种有用的催化和吸附材料。

Na-montmorillonite was used as starting material to obtain Al-Cr-montmorillonite. Al-Cr-pillared agent was synthesized by ion-exchange method and Al-Cr-montmorillonite was prepared with wet technology. The effects of molar ratio of Cr ion to Al ion and pH value on Al-Cr-montmorillonite were investigated. The results show that the （001） basal spacing of Al-Cr-montmorillonite reaches 2.053 5 nm when Al-Cr-montmorillonite is synthesized under the condition of 2：1 molar ratio of Cr ion to Al ion and 100 mL 0.4 mol/L NaOH,the Cr-Al polyoxocations insert into the montmorillonite. The basic structure of montmorillonite remains unchange,（Cr—O）Oh is detectable and （Cr—O）Td band is not found,and Cr3＋ tends to adopt octahedral coordination instead of tetrahedral to enter into the layers of montmorillonite. The specific area,average mesopore diameter and pore volume of Al-Cr-montmorillonite are 170.4 m2/g,3.840 nm and 0.184 1 cm3/g,respectively. Al-Cr-montmorillonite has larger specific area,relatively larger micropore diameter and smaller mesopore diameter which is a useful adsorption and catalysis material.