催化学报

催化学报 ›› 2006, Vol. 27 ›› Issue (11): 1012-1018.

• 研究论文 • 上一篇    下一篇

沉淀剂种类对水煤气变换Au/Fe2O3催化剂结构和催化性能的影响

华金铭1,2,郑起2,魏可镁2,林性贻2   

  1. 1 紫金矿业集团股份有限公司紫金矿冶设计研究院, 福建上杭 364200; 2 福州大学化肥催化剂国家工程研究中心, 福建福州 350002
  • 收稿日期:2006-11-25 出版日期:2006-11-25 发布日期:2006-11-25

Effect of Precipitants on Structure and Catalytic Activity of Au/Fe2O3 Catalysts for the Water-Gas Shift Reaction

HUA Jinming1,2, ZHENG Qi2*, WEI Kemei2, LIN Xingyi2   

  1. 1 Zijin Research and Engineering Institute of Mining and Metallurgy, Zijin Mining Group Co. Ltd., Shanghang 364200, Fujian, China; 2 National Research Center of Chemical Fertilizer Catalyst, Fuzhou University, Fuzhou 350002, Fujian, Chin
  • Received:2006-11-25 Online:2006-11-25 Published:2006-11-25

PDF

833

被引次数

27

摘要： 采用7种沉淀剂(K2CO3, Na2CO3, NH4OH, (NH4)2CO3, NaOH, KOH和尿素)通过共沉淀法制备了低温水煤气变换(WGS) Au/Fe2O3催化剂,考察了沉淀剂种类对其催化性能的影响. 通过N2吸附, X射线荧光光谱、 X射线衍射、 H2程序升温还原和CO程序升温脱附等表征手段,探讨了不同沉淀剂影响Au/Fe2O3催化剂WGS性能的原因. 结果表明,采用K2CO3和Na2CO3制备的催化剂样品在200 ℃以上具有较好的活性和稳定性,其中K2CO3是最佳沉淀剂. 而采用NH4OH和(NH4)2CO3制备的样品的催化活性相对较低,在200 ℃达到峰值. 由其它3种沉淀剂制备的样品的催化活性都较差, CO转化率最高只有35%. 沉淀剂种类不仅明显地影响金离子和铁离子的共沉淀,而且会明显地影响共沉淀物在后续焙烧过程中的结晶行为. 前者将影响金的负载量,后者则影响金粒子的分散度以及氧化铁载体的还原性质和对CO的吸脱附性能. Au/Fe2O3催化剂的低温高活性及其稳定性归因于高度分散的金粒子及其与易被还原的氧化铁载体间的协同作用. 催化剂中金负载量增大、金粒子分散度提高以及氧化铁晶粒减小均有利于其催化性能的提高.

关键词: 水煤气变换反应, 金, 负载型催化剂, 氧化铁, 沉淀剂, 共沉淀

Abstract: Au/Fe2O3 catalysts were prepared by the coprecipitation method using seven precipitants, K2CO3, Na2CO3, NH4OH, (NH4)2CO3, NaOH, KOH, and urea. These catalysts were used for the low temperature water-gas shift reaction and characterized by N2 adsorption-desorption, X-ray fluorescence spectroscopy, X-ray diffraction, H2 temperature-programmed reduction, and CO temperature-programmed desorption to explore the cause resulting in their significant difference of catalytic activity. The catalysts prepared using K2CO3 or Na2CO3 as the precipitant exhibited higher activity and better stability above 200 ℃. The samples precipitated with NH4OH or (NH4)2CO3 showed moderate activity maximizing at 200 ℃. The samples prepared using the rest three precipitants presented almost no activity below 300 ℃, attaining only 35% of CO conversion above 350 ℃. The type of precipitant exerted significant effect on the coprecipitation of gold and iron ions, and the crystallization behavior of the resulting precipitates during the subsequent calcination step, which further influenced the gold loading, the dispersion of gold particles, and the reduction and CO adsorption-desorption properties of the iron oxide support. The high catalytic activity of Au/Fe2O3 catalysts at low temperature can be attributed to the synergism between higher dispersion of gold particles and easier reduction property of the iron oxide support. The increase in gold loading and dispersion of gold particles and the decrease in the iron oxide crystallites are favorable for improving the catalytic activity of the Au/Fe2O3 catalysts.

Key words: water-gas shift reaction, gold, supported catalyst, iron oxide, precipitant, coprecipitation