CeO_2-CuO/ZnO/Al_2O_3催化合成二乙基甲苯二胺及性质

采用柠檬酸为络合剂,溶胶-凝胶法制备系列CeO_2-CuO/ZnO/Al_2O_3,在3.0 MPa压力和220~230℃反应条件下,甲苯二胺(TDA)和乙烯催化合成二乙基甲苯二胺(DETDA)为探针反应,考察其催化性能,其中CeO_2掺杂量为3%,催化活性最高。通过X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、差热重量分析法(DTG-DTA)、核磁氢谱1 H NMR对CeO_2-CuO/ZnO/Al_2O_3、DETDA、TDA进行检测和表征,揭示了它们的微观结构和内在规律性。XRD检测发现CeO_2掺杂量增多,CeO_2-CuO/ZnO/Al_2O_3衍射峰强度增强,提高了晶化程度,金属原子存在协同效应,增多了活性中心。FT-IR揭示了DETDA内部化学键键型,拥有甲基、亚甲基的多取代芳胺。DTG-DTA检测出的质量变化与热效应两种信息,DETDA的DTG-DTA曲线在66.0、271.0℃存在二个吸热峰,分别为氨基脱离苯环、DETDA的分解产生。通过1 H NMR对DETDA、TDA检测,得到DETDA、TDA的氢原子的数目分别为18和10,分子中各个氢核对应所归属的吸收峰,分别和它们分子式中的氢原子数目吻合。CeO_2-CuO/ZnO/Al_2O_3催化合成DETDA,反应条件温和,工艺流程简单,容易实现高效率和连续化工业生产,因此具有广阔的发展前景。

Apparent activation energy for spontaneous combustion of sulfide concentrates in storage yard

In order to evaluate the spontaneous combustion hazard of sulfide concentrates in storage, three different kinds of sulfide concentrates （sulfur-rich sulfide concentrate, iron sulfide concentrate and copper sulfide concentrate） were obtained from a storage yard in Dongguashan Copper Mine, China. The reaction processes at different heating rates of 5, 10, 15, 20, and 25 ℃/min in air flow from ambient temperature to 1 000 ℃ were studied by TG-DTG-DSC analysis. By the peak temperatures of DTG curves, the whole reaction process for each sample was divided into different stages, and the corresponding apparent activation energies were calculated by the Ozawa-Flynn-Wall method. It is found that the reaction process of each sample is considerably complex; the apparent activation energy values change from 36 to 160 kJ/mol in different temperature ranges; sulfur-rich sulfide and iron sulfide concentrates have lower apparent activation energy than copper sulfide concentrate below 150 ℃; so they are more inclined to cause spontaneous combustion at ambient temperature.