制备方法对Ag-Ru/CeO2氨合成催化剂性能的影响

采用共沉淀法（CP）、改性沉淀沉积法（MDP）、浸渍法（IP）制备了Ag-Ru/CeO₂催化剂,并运用N₂物理吸附、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、N₂程序升温脱附（N₂-TPD）等技术对其进行了表征,考察了个同制备方法对Ag-Ru/CeO₂催化剂氨合成性能的影响.结果表明:不同方法制备的催化剂,银助剂对载体的还原性能和氮气的解离吸附性能的影响存在明显的差别,从而影响了催化剂的氨合成活性,其中采用浸渍法制备的催化剂氮气解离吸附最强,载体最易于还原,因此催化剂低温氨合成活性最高,在10 MPa,10000 h^-1,400℃反应条件下,出口氨浓度达到9.4%.

Effect of Preparation Methods on the Catalytic Activity of Ag-Ru/CeO2 Catalyst for Ammonia Synthesis

Ag-Ru/CeO₂ catalysts were prepared by co-precipitation（CP）,modified deposition precipitation （MDP）,and incipient-wetness impregnation（IP）.The obtained catalysts were characterized by N₂ physisorption,X-ray diffraction（XRD）,H₂ temperature-programmed reduction（H₂-TPR）,and temperature-programmed desorption of nitrogen（N₂-TPD）.The results showed that the ammonia synthesis activity of the Ag-Ru/CeO₂ catalyst prepared by incipient-wetness impregnation was 9.4%at 10 MPa,10000 h^-1 and 400℃,which was higher than that obtained by other methods.There were obvious differences in the reduction property of Ru/CeO₂ and in the nitrogen dissociation behavior among the catalysts prepared by different methods.Catalyst activity for the catalyst prepared by incipient-wetness impregnation improved greatly at a low reaction temperature.The high catalytic activity was due to the easier reduction of Ag-Ru/ CeO₂ and the higher amount of dissociation of chemisorbed nitrogen.