Au/Ce_(1-x)Zr_xO_2催化剂的制备、表征及其在CO氧化和水煤气变换反应中的催化性能  

Preparation and Characterization of Au/Ce_(1-x)Zr_xO_2 Catalysts and Their Catalytic Performance for CO Oxidation and Water-Gas Shift Reaction

作　　者：廖卫平[1] 董园园[1] 金明善[1] 何涛[1] 索掌怀[1] 

机构地区：[1]烟台大学应用催化研究所,山东烟台264005

出　　处：《催化学报》2008年第2期134-140,共7页

基　　金：国家自然科学基金(20473070);山东省自然科学基金(Y2004B07)

摘　　要：采用共沉淀法制备了不同锆铈摩尔比的Ce1-xZrxO2(x=0,0.1,0.3,0.5,0.7,0.9和1.0)氧化物,并以改性的浸渍法制备了金担载量为1%(质量分数)的Au/Ce1-xZrxO2催化剂.考察了催化剂在低温CO氧化和水煤气变换反应中的催化性能.应用氮物理吸附、X射线衍射、透射电镜和H2程序升温还原等技术对氧化物载体及其负载金催化剂进行了表征,并与其催化性能进行了关联.结果表明,与纯CeO2和ZrO2相比,Ce1-xZrxO2的比表面积增大而孔径减小,孔分布更加集中.Zr的加入使表面Ce4+的还原更加困难,使体相Ce4+的还原更加容易.活性组分金的加入有利于铈锆氧化物的还原.ZrO2载体较大的孔径使金在载体表面分散均匀而粒子较小,因此与Au/CeO2和Au/Ce1-xZrxO2相比,Au/ZrO2具有更好的低温CO氧化活性和水煤气变换活性,而Au/CeZrO在高温下的水煤气变换反应中表现出更好的催化性能.Aseriesof Ce1-xZrxO2 （x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0） composite oxides were prepared by the co-precipitation method. Gold catalysts with 1% loading supported on CeO2, ZrO2, and Ce1-x, ZrxO2 were prepared by the modified impregnation method. The effect of Zr/Ce molar ratios on the activity for low-temperature CO oxidation and water-gas shift reaction was studied. All samples were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and H2 temperature-programmed reduction. The resuits showed that compared with pure CeO2 and ZrO2, the surface area of Ce1-xZrxO2 increases and its pore diameter decreases slightly. The presence of zirconium oxide in cerium oxide makes the reduction of cerium ions on the surface more difficult whereas it makes the reduction of the cerium ions in the phase easier. Loading gold particles onto Ce1-xZrxO2 support improves the reduction of the support, and good dispersion of gold particles is found on ZrO2 and Ce1-xZrxO2 supports due to the strong interaction between the gold particles and the oxide supports. These catalysts show good activity for low-temperature CO oxidation and water-gas shift reaction in the order au/ZrO2 〉 Au/Ce1-xZrxO2 〉Au/CeO2. However, au/Ce0.5Zr0.5O2 gives higher activity with 80% CO conversion at 623 K for water-gas shift reaction. Large pore diameter of ZrO2 and Ce1-xZrxO2 with respect to CeO2 is responsible for the high activity.

关 键 词：氧化铈 氧化锆 复合氧化物 金催化剂 一氧化碳氧化 水煤气变换 

分 类 号：O643.3[理学—物理化学]