焙烧复原法制备的柱撑水滑石及其结构表征

Pillared hydrotalcite produced by calcine-recovering method and its structure characterization.

通过共沉淀法合成了锌铝碳酸根型水滑石(LDH)前体.X-射线衍射分析显示,它在c轴方向的层间距,即d003随着Zn/Al比减小而缩减.这一特征在柱撑反应产物中被继承.将前体在550℃温度下焙烧5 h得到双金属氧化物(LDO),将其分别加入到十二烷磺酸钠(SDDS)和山梨酸(SBA)的水溶液中,在90℃水浴中恒温搅拌3 h.所得产物经XRD和FTIR表征,确认为DDS和SBA柱撑LDH.上述焙烧复原法合成的柱LDH均具有两套底面衍射,其中一套具单层结构,即八面体层和阴离子层为1∶1关系;另一套为双层结构,每两个八面体之间有一层阴离子.这两种结构的柱撑水滑石在合成产物中是混合物还是混层矿物待进一步工作确认.90℃以上的热水介质、具有半导体性质的前体以及亲水性柱撑剂对合成2∶1型柱撑水滑石有利.

Zn-Al-carbonate hydrotalcite（LDH） was synthesized by coprecipitaion method and was used as precursor. XRD analysis showed that the basal spacing of Zn-Al-LDH along c axis, i. e. ,d003 value falls with decreasing Zn/Al ratio. This feature is inherited in its pillared products. The precursor was calcined at 550℃ for 5 hours to get layered double oxide（LDO）, which was then added into boiled Sodium dodecyl Sulfate（SDDS） and sorbic acid（SBA） solu tion, respectively, stirring for 3 hours in a thermo-bath at 90℃. The products were characterized by XRD and FTIR. It was confirmed that DDS and SBA pillared LDH was successfully synthesized. The pillared LDHs produced by this method are characterized by two sets of basal spacing. One of them fits with monolayer structure, i. e. , octa hedron layer and anion is in 1 ; 1 ration; another set of basal spacing refers to a double-layered structure, two layers of octahedron sheets are interbedded with an anion layer. It is still an open problem for further study that if this two kinds of structure in the same sample is a mixture or a mix-layered mineral. Thermo-water above 90℃, semi-conductive precursor and hydrophilic pillar agent are favorable conditions for synthesizing pillared LDH with 2 ： 1 structure.