【作者】 王军涛；

【导师】 詹正坤；

【作者基本信息】 华中师范大学 ， 物理化学， 2005， 硕士

【摘要】 水滑石是一种具有层状结构的阴离子粘土,具有酸性和碱性特征、微孔结构、记忆效应及层间阴离子的可交换性。水滑石的这些功能和性质与层板中不同金属原子物质的量之比有密切关系。因此我们合成了几种水滑石的系列产物,对其结构上的差异作了较为深入的研究。另外,利用水滑石层问阴离子的可交换性进行插层组装是国内近年来兴起的热点,所以我们也对部分合成出来的水滑石进行了初步的插层组装。 采用共沉淀法合成了金属原子的物质的量之比分别为2,3,4的碳酸根型MgFe、CoFe、CoAl三个系列的水滑石,用XRD、TG-DTA和IR等方法对其组成和结构进行了研究。 XRD测试结果证实了所合成的水滑石晶形良好,纯度很高。其中MgFe水滑石的晶形最好,CoAl其次。三种水滑石的系列产物的晶胞参数均呈有规律的变化。 TG-DTA测试结果说明,MgFe水滑石有两个吸热分解过程,CoFe水滑石只有一个吸热分解过程。根据吸热峰峰值温度可知,MgFe水滑石的热稳定性强于CoFe水滑石。同时,水滑石在这两个过程中均有失重,不同样品的失重率不同。 IR分析结果证实了水滑石层间阴离子是对称性良好的CO₃²⁺,所测样品均反映出了水滑石层中晶格氧的振动峰,进一步证实了碳酸根型水滑石的成功合成,而且IR结果同样显示了不同水滑石结构上的规律性差异。 以MgFe碳酸型水滑石的系列产物为主体,几种有机酸为客体对其进行插层组装,并用XRD、IR、TG-DTA等手段对组装产品进行了分析和表征。结果表明,通过控制离子交换时的pH,可使草酸根、富马酸根取代MgFe碳酸型水滑石层间的CO₃^2-。更多还原

【Abstract】 Hydrotalcite are a sort of layered anionic clays with acid properties, basic properties, micropore structure, memory effect and interlayer anionic exchangeability and adjustability. For the reason, it is also a kind of new important catalytic and functional material. The molar rations of different metal atoms in hydrotalcite affect it’s functions and properties greatly. So we synthesis three kinds of hydrotalcite and study their structure differences. Recently, the research work of organic anion pillared hydrotalcite assembled by anion exchange method using hydrotalcite as a precursor is proceeding, and we also do the same work using MgFe hydrotalcite.Three series of carbonate pillared MgFe、 CoFe、 CoAl hydrotalcites with different adding M2+/M3+ molar rations are synthesized by coprecipitation. XRD、 IR and TG-DTA are used in search of the composition and structure of the products.The results of the XRD measurement certify that the hydrotalcites have nice crystal forms and high purity. Cell parameters of all these hydrotalcites change regularly.It can be seen from the TG-DTA curves MgFe hydrotalcite has two endothermic decomposition stages but CoFe has only one. The thermal stability of MgFe hydrotalcite is higer than CoFe hydrotalcite. All hydrotalcites will lose weight in decomposition stage and different samples exhibit different rates of weight loss.The results of IR analysis tell us it is Co32- the that has been intercalated between the double layers of hydrotalcite-structure. There are peaks reflecting M-0 vibration in hydrotalcites in all of the IR spectra of the tested samples.They both show that the synthesis of hydrotalcites is successful. And IR also tell us the structure differences of different samples. Organic anion pillared MgFe hydrotalcite are assembled by anion exchange method with MgFe hydrotalcite being theprecursor. The samples were analyzed by XRD、IR and TG-DTA. The results showed that by controlling the pH of the ion-exchange medium, organic anions can replace carbonate ions in the interlayeres.更多还原