柱撑粘土矿物材料的晶体结构和晶体化学特征

以铝基柱撑粘土矿物和钛基柱撑粘土矿物为例,讨论了柱撑粘土矿物材料的晶体结构和晶体化学特点,Al多核笼状阳离子基团的结构形式为1：12Keggin型离子,Ti多核笼状阳离子基团的结构形式为2：19Dawson型离子,两类笼状阳离子的直径均在1nm左右,前者的高度约为0．9nm,后者的高度约为1．4nm,经与粘土矿物层间阳离子交换后,择位固定在粘土矿物层间,由于多核笼状阳离子与粘土矿物硅氧四面体之间形成了较强的化学键,其具有不可交换性,铝基柱撑粘土和钛基柱撑粘土的层间孔道分别为1．2nm*1.2nm*1.2nm,和0.52nm*0.52nm*1.60nm。柱粘土矿物材料有很好的化学稳定性和耐热性,且又有一定的层间化学活性,可用于催化剂载体,由于它又具有选择性吸附能力,有望制造成新一代环保材料。

CRYSTAL STRUCTURE AND CRYSTAL CHEMISTRY OF PILLARED CLAY MINERAL MATERIALS

Taking the Al-pillared and Ti-pillared clay minerals as examples,the crystal structure and crystal chemistry of pillared clay mineral materials are discussed in this article.Al-polymeric cations have a structure of 1∶12 Keggin type,and Ti-polymeric cations of 2∶18 Dawson type.Both of them are about 1.0 nm in diameter, but the former is about 0.9 nm in height,the latter about 1.4 nm.By exchanging the cations in the interlayer of the clay minerals,they can be fixed in the interlayer region.The stronger chemical bonds are formed between the polymeric cations and the silicon-oxygen tetrahedral sheet of the clay minerals,so the polymeric cations are non-exchangeable.The porosities in　the interlayer region of the Al-pillared and Ti-pillared clay minerals are 1.2 nm×1.2 nm×1.2 nm and 0.52 nm×0.52 nm×1.6 nm,alternatively.Pillared clay mineral materials possess higher chemical and thermal stability,and also they are chemically active in the interlayer region, so they can be used as the catalytic media.As they have selectively-absorbing property,they may be a new type environment protection material.