载体对负载型金催化剂上甲醛催化氧化的影响

Support Effect on Catalytic Oxidation of Formaldehyde over Supported Gold Catalysts

采用沉积-沉淀法和氨水络合法制备了Al2O3,TiO2,CeO2和SiO2负载的纳米金催化剂,利用元素分析、X射线衍射、氮气物理吸附、程序升温还原、透射电镜和拉曼光谱等技术对催化剂进行了表征,并考察了其低温催化甲醛氧化活性.结果表明,Au/CeO2的催化性能最佳,在40oC时甲醛转化率仍能保持在80%以上.催化剂的活性同时受Au的化学状态和载体性质的影响.Au/CeO2催化剂较高的低温活性可能与离子态的Au物种有关,同时AuxCe1-xO2-δ固溶体的形成产生了大量的氧缺位,提高了氧的活化能力,也有助于提高催化剂的低温活性.

A series of gold catalysts were prepared by a deposition-precipitation method and an ammonia-complex method on different metal oxides （Al2O3, TiO2, CeO2, and SiO2） and tested for low temperature HCHO oxidation. The Au/CeO2 catalyst exhibited the highest activity with 80% of conversion obtained even at 40℃. The catalysts were characterized by inductively coupled plasma, X-ray diffraction, N2 adsorption, temperature-programmed reduction, transmission electron microscopy, and Raman spectroscopy. The results show that the reactivity of HCHO oxidation is influenced by the chemical state of Au species and the properties of the supports. The high activity obtained on the Au/CeO2 catalyst was probably due to the presence of cationic Au species （Au^3＋） in the catalyst and the formation of AuxCe1-xO2-δ solid solution, which generates oxygen vacancies and activates the oxygen species and consequently enhance the activity.