【作者】 齐绍英；

【导师】 黄碧纯；

【作者基本信息】 华南理工大学 ， 环境工程， 2010， 硕士

【摘要】 柴油车尾气排放的碳烟颗粒已引起严重的环境污染问题,柴油车排气标准也在不断提高。CuO-CeO2催化剂可在较低温度下加快碳烟颗粒的氧化速率,它主要靠表面活性氧来发挥高催化性能。论文主要考察制备过程中溶剂对CuO-CeO2催化剂表面活性氧的影响。论文以分别采用无水乙醇和水作溶剂的柠檬酸络合燃烧法制备的催化剂CuO-CeO2-A和CuO-CeO2-W为研究对象,采用程序升温氧化(TPO)、程序升温还原(H2-TPR)、程序升温脱附(O2-TPD)、X-射线衍射(XRD)、傅立叶变换红外光谱(FTIR)、X-射线光电子能谱(XPS)等技术对催化剂进行表征。研究了不同溶剂对CuO-CeO2催化剂表面活性氧的影响及对氧化活性产生差异的主要原因。主要研究结果如下：(1)以无水乙醇和水作溶剂的柠檬酸络合燃烧法制备的催化剂CuO-CeO2-A和CuO-CeO2-W具有相同的晶体结构,均形成了Cu-Ce-O固溶体,溶剂的改变没有导致催化剂结构的不同。(2)乙醇可以加强CuO的极性,改善CuO在CeO2表面的分散状态,增加β氧物种,进而提高CuO-CeO2对CO的氧化活性；但由于在碳烟的氧化过程中起主要作用的是α氧种,而非β氧种,所以CuO-CeO2-A没有提高对碳烟的氧化活性。(3)溶剂对柠檬酸络合燃烧法制备的CuO-CeO2氧化碳烟的活性影响主要是通过改变催化剂表面CuO的分布状态和催化剂的储氧容量来实现的。(4)乙醇作溶剂的柠檬酸络合燃烧法制备的CuO-CeO2-A系列催化剂在n(Ce)/(n(Ce)+n(Cu))>20%时,保持Ce02的立方萤石结构；n(Ce)/(n(Ce)+n(Cu))<20%时,开始有晶相CuO形成。(5)在反应气氛中无NOx、SO2等存在的条件下,晶格氧含量对由水和无水乙醇作溶剂柠檬酸络合燃烧法制备的系列催化剂CuO-CeO2催化氧化碳烟的活性影响不大。更多还原

【Abstract】 Soot particles in exhaust gas from diesel-fuelled vehicles have caused a serious environmental pollution, thus promoting the establishment of more emission standards. CuO-CeO2 was found to accelerate soot combustion under low temperature. The catalytic performance was guaranteed mainly due to its active oxygen species. Therefore, this paper studied the effects of solvent used in the preparation process on active oxygen species.In this paper, catalysts CuO-CeO2-A and CuO-CeO2-W were prepared using the method of citrate acid complex-combustion, and absolute alcohol and water were used as the solvents for comparsion, respectively. Characterization techniques were used, including temperature programmed oxidation (TPO), and characterized by temperature programmed reduction (H2-TPR), temperature programmed desorption (O2-TPD), x-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR), and x-ray photoelectron spectroscopy(XPS).The effect of different solvents on surface active oxygen species as one of activity factors was inverstigated. The main results are as follows:(1) The same crystal structure was found in CuO-CeO2-A and CuO-CeO2-W, prepared by citrate acid complex-combustion with absolute alcohol or water as solvents. And both of the catalysts exhibited the formation of solid solution.(2) Absolute alcohol could enhance the distribution of CuO on surface of CeO2 and increases the amount ofβoxygen, which favors the oxidation of CO, not soot. For soot oxidation, the main active oxygen species is a oxygen, but notβoxygen.(3) Solvent affects the catalytic activity mainly via changing the distribution of CuO and oxygen storage capacity of catalyst.(4) CuO-CeO2-A prepared by citrate acid complex-combustion using absolute alcohol as the solvent keep the cubic fluorite structure as CeO2 until n(Ce)/(n(Ce)+n(Cu)<20%, and then CuO in crystal phase is formed.(5) Without NOx and SO2 in act system, the amount of lattice oxygen has no effect on catalytic activity for CuO-CeO2 prepared by citrate acid complex-combustion with absolute alcohol or water as solvents to catalytic combustion of soot.更多还原