中文摘要：

热处理是凹凸棒石黏土活化改性的常用方法之一。认识热处理过程中凹凸棒石结构演化，特别是凹凸棒石结构中铝配位的变化规律，对于理解凹凸棒石热活化改性的本质是十分重要的，可以为凹凸棒石黏土热化处理提供理论依据。为此，利用27Al魔角旋转核磁共振（MAS-NMR）技术结合X射线衍射分析，研究了经250～900 ℃热处理的凹凸棒石结构铝配位的变化。结果表明：天然凹凸棒石中铝主要是6配位（铝替代八面体中的镁），有很少量的4配位铝存在（铝替代硅氧四面体中的硅位置），并且在凹凸棒石硅氧四面体的四重周期中存在2个不同的晶格位置；煅烧温度在500 ℃以下时，铝配位没有发生明显变化；煅烧温度升高到500 ℃以上时，4配位铝明显增加，并且存在两种不同的晶格位置，表明结构有序性并没有完全破坏，同时还出现了少量的5配位铝。经600 ℃热处理后，凹凸棒石中铝6配位急剧降低，基本转化为4配位；温度升高到800 ℃时，6配位以及作为中间态出现的5铝配位完全消失，并且4配位铝峰只有一个峰，表明经过800 ℃高温处理后4配位铝都处于相同的化学环境。

英文摘要：

Thermal treatment is a common method to active palygorskite. It is thus important to investigate the effect of thermal treatment on palygorskite’s structural properties, especially on the Al coordination. The coordination structure transformation of Al in the thermally-treated palygorskite samples from 250 ℃ to 900 ℃ was investigated by 27Al magic-angle spinning nuclear magnetic resonance （MAS-NMR）. The results show that Al in untreated palygorskite is chiefly Al（Ⅵ）, which subsititutes Mg in octahedral, along with a minor amount of Al（Ⅳ）, which subsititutes Si in tetrahedral. There exist two different lattice positions in Si–O tetrahedral. No significant change appears when treated at the treatment temperature of 〈 500 ℃. The peak of Al（Ⅳ） is strengthened and a signal of Al（Ⅴ） is detected when treated at 〉 500 ℃. There are two lattice positions existed at the same time, showing that the orderly structure is not destroyed compeletly. The peak of Al（Ⅵ） decreases and Al appears as Al（Ⅳ） after treated at 〉 600 ℃. At 800 ℃, Al（Ⅵ） and Al（Ⅴ） disappear completely, and the peaks of Al（Ⅳ） turn to form one peak, indicating that all the Al（Ⅳ） exists in one chemical environment.