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1、中南民族大学 硕士学位论文 卟啉化合物的热行为研究及尖晶石结构功能材料的溶胶-凝胶法 制备 姓名：韦秀华 申请学位级别：硕士 专业：物理化学 指导教师：陈栋华 20060510 中南民族大学硕士学位论文 I 摘摘 要要 本文概述了热分析技术在卟啉类化合物研究中的应用以及尖晶石结构功能材 料的研究进展对热分解动力学三因子求算的主曲线法和比较法进行了对比 研究研究结果验证了两种方法的可靠性与一致性分析了卟啉类化合物的热稳 定性并确定其熔点和熔融焓用主曲线法求算高温热降解过程的动力学三因 子 为了进一步降低尖晶石结构功能材料的烧成温度探讨了溶胶凝胶法和共 沉淀法最适宜的合成条件并对结果产品进行了各种
2、表征主要工作有以下几个 部分 因比较法和主曲线法在求算热分解动力学三因子时基本原理和处理方法 不同 为此探讨了两种方法处理的结果是否一致 本文利用热重分析技术研究了 碳酸钙热分解过程通过这两种方法分别求算了碳酸钙热分解反应动力学三因 子 比较法结果活化能 Ea为 174.00 kJmol- 1指前因子 A 为 9.63106 s- 1机 理函数微分形式和积分形式分别为 f ()= 2/1 )1 (2a和 g()= 2/1 )1 (1a主曲线 法结果活化能 Ea=169.81 kJ/mol指前因子 A=3.84 6 10 s1机理函数微分表达 式为 f()= 2(1- a)1/1.57积分表达式
3、为 g()=1(1a)1/1.57两种方法所得结果基 本吻合说明了两种方法判定动力学三因子的一致性和可靠性 利用热重分析手段研究 5101520- 四4- 甲氧苯基卟啉4- TMPP5 101520- 四3- 甲氧苯基卟啉3- TMPP及其相应的镍络合物4- TMPP- Ni 和 3- TMPP- Ni在空气中的热稳定性4- TMPP 和 4- TMPP- Ni 相对于 3- TMPP 和 3- TMPP- Ni 较稳定镍卟啉比相应的卟啉稳定采用差示扫描量热分析和红外光 谱分析确定四种样品的熔点和熔化焓结合热重分析数据求算热分解动力学三 因子Eaf()A通过非模型积分方式计算 4- TMPP-
4、 Ni 和 3- TMPP- Ni 热分 解反应的活化能主曲线方法确定机理函数和指前因子两样品的热分解遵从相 同的动力学模型即 Avramie- Erofeev 方程ng)1ln()(=具体的机理函数积 分形式分别是 278. 0 )1ln()(=g和 260. 0 )1ln()(=g 卟啉化合物的热行为研究及尖晶石结构功能材料的溶胶- 凝胶法合成 II 以草酸为络合剂乙二醇为溶胶稳定剂硝酸盐为原料采用溶胶- 凝胶法合 成了 M(M= Zn Ni Mg)- Al 凝胶前驱体 高温煅烧凝胶前驱体即可制得 MAl2O4 尖 晶石纳米粉体采用热重和差示扫描量热两种分析手段研究了前躯体的热行为X 射线
5、衍射结果表明该方法能明显降低 MAl2O4 的合成温度在 700 煅烧 4 小 时已能得到单相尖晶石纳米粉体红外结果也能很好的佐证这一点此方法的煅 烧温度比微波反应法合成温度降低 200比铝单醇盐溶胶凝胶法降低 100 通过电子显微镜测得粉体的平均粒径约为 15 nm 以草酸为沉淀剂 乙醇为溶剂通过新型共沉淀法合成分子前躯体锌钴草酸复合 盐 ZnCo2(C2O4)34H2O对该前躯体在不同温度下热处理即可制得锌钴尖晶石粉 体利用热重分析仪和差示扫描量热仪对前躯体热分解过程分别进行热失重分析 和动力学分析结果表明前躯体热分解仅经历两个热失重过程脱结晶水和最 后分解且最后分解过程遵循随机成核和核随
6、后生长单一的动力学机理活化能 不随转化率的变化而变化由此说明前驱体为草酸复合盐而不是二元混合盐利 用 XRDIR 和 TEM 等分析手段对尖晶石粉体进行表征结果显示前躯体在低 温段 450650 煅烧 2h 即可获得单相颗粒细小均匀的尖晶石粉体高温 750 煅烧得到 ZnO 和缺锌的锌钴尖晶石的混合物此新型共沉淀法为制备高纯单 相的 ZnCo2O4尖晶石提供了一种简便有效的方法 关键词卟啉热分析尖晶石溶胶凝胶法草酸XRD 中南民族大学硕士学位论文 III Abstract In this paper, the application of the thermal analysis techni
7、que in the study of porphyrins and the present situation of the spinel structure functional materials were introduced. The master plots method and comparative method used to calculate the thermal decomposition kinetics triplets were researched contrastively. The research results confirmed that the t
8、wo methods are all reliable and consistent with each other. The thermal behaviors such as thermal stability, melting temperature and melting enthalpy of porphyrins were measured. In addition, we calculated the kinetics triplets of thermal decomposition of porphyrins using master plots method. In ord
9、er to decrease the calcinations temperature of spinel structure functional materials fartherly, we discussed the optimum synthesis conditions of sol- gel method and coprecipitation method. The resulting products were characterized by various measurements. The major work is as following. The basic th
10、eory of comparative method and master plots method in calculating kinetics triplets are different. In order to confirm that the results obtained by the two methods are consistent with each other, we have investigated the thermal decomposition process of CaCO3 using TG technique. The kinetic triplets
11、 of thermal decomposition of CaCO3 are obtained through comparative method and master plot method, respectively. The results of comparative method as follows: The apparent activation energy Ea is 174.00 kJmol 1, the pre- exponential factor A is 9.63106 s- 1, the most probable mechanism function is f
12、()= 2/1 )1 (2aor g()= 2/1 )1 (1a. The results of master plot method as follows: the apparent activation energy Ea is 169.81 kJ/mol, the pre- exponential factor A is3.84 6 10 s- 1, the most probable mechanism function is f()=2(1- a)1/1.57 or g()=1(1a)1/1.57. The results obtained by the two different
13、methods are almost the same, which suggest that the two methods are accordant and 卟啉化合物的热行为研究及尖晶石结构功能材料的溶胶- 凝胶法合成 IV successful in determining kinetic triplets. The thermal stability in air of 5,10,15,20 - tetrakis (4- methoxyphenyl) porphyrin (4- TMPP), 5,10,15,20 - tetrakis (3- methoxyphenyl) porp
14、hyrin (3- TMPP), and their nickel metallo- complexes (4- TMPP- Ni and 3- TMPP- Ni) has been investigated by thermogravimetry (TG). 4- TMPP and 4- TMPP- Ni exhibit higher thermal stability compared to 3- TMPP and 3- TMPP- Ni. Nickel complexes exhibit a little higher thermal stability than the corresp
15、onding porphyrins. The thermal behavior including melting temperature and enthalpy of fusion was determined by differential scanning calorimetry (DSC) and infrared spectra (IR). The activation energies of thermal decompositions of 4- TMPP- Ni and 3- TMPP- Ni were obtained by integral model- free met
16、hod; the mechanism functions and pre- exponential factors were determined by master plots method. The kinetic models follow the same mechanism function, Avramie- Erofeev equations with integral forms 278. 0 )1ln()(aag= and 260. 0 )1ln()(aag=, respectively. Nanosized aluminate spinel has been obtained by the thermal decomposition of MAl gel prepared by solgel technique using oxalic acid as a chelating agent. Stirring an enthanol solution of nitrat
