物理化学学报 >> 2008, Vol. 24 >> Issue (11): 2108-2113.doi: 10.1016/S1872-1508(08)60080-7

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CeO2-MOx (M=La3+, Ca2+)改性Pd/γ-Al2O3催化甲烷燃烧性能

肖利华, 孙鲲鹏, 徐贤伦   

  1. 浙江工业大学催化研究所, 绿色化学合成技术国家重点实验室培育基地, 杭州 310032; 中国科学院兰州化学物理研究所,羰基合成与选择氧化国家重点实验室, 兰州 730000
  • 收稿日期:2008-04-14 修回日期:2008-06-27 发布日期:2008-11-10
  • 通讯作者: 肖利华 E-mail:lhxiao@zjut.edu.cn

Catalytic Combustion of Methane over CeO2-MOx (M=La3+, Ca2+) Solid Solution Promoted Pd/γ-Al2O3 Catalysts

XIAO Li-Hua, SUN Kun-Peng, XU Xian-Lun   

  1. State Key Laboratory Breeding Base of Green-Chemistry Synthesis Technology, Institute of Resources and Environment Catalysis, Zhejiang University of Technology, Hangzhou 310032, P. R. China; State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P. R. China
  • Received:2008-04-14 Revised:2008-06-27 Published:2008-11-10
  • Contact: XIAO Li-Hua E-mail:lhxiao@zjut.edu.cn

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摘要： 采用沉积-沉淀法制备了固溶体CeO2-MOx(M=La3+, Ca2+)改性的Pd/γ-Al2O3催化剂, 利用XRD、Raman和XPS对催化剂进行了表征. 结果表明, 金属(M)离子进入CeO2的晶格, 形成CeO2-MOx固溶体, Raman谱上463 cm-1处对应于Ce—O键的F2g对称伸缩振动强度降低. 其中, 样品Pd/γ-Al2O3-CeO2-CaO在615 cm-1处出现一小峰, 样品Pd/γ-Al2O3-CeO2-La2O3在320 cm-1处出现的肩峰, 都表明固溶体CeO2-MOx的形成使O2-亚晶格结构对称性降低. XPS分析表明, 固溶体改性的Pd/γ-Al2O3催化剂中Pd 的3d5/2结合能比正常价态的PdO的结合能高出0.5-0.6 eV, 形成了一种高度离子化的, 与载体具有强相互作用的Pd物种. 催化甲烷燃烧实验证明, 固溶体CeO2-MOx(M=La3+, Ca2+)改性的Pd/γ-Al2O3催化剂的低温活性和稳定性均高于未经改性的Pd/γ-Al2O3催化剂和仅用CeO2改性的Pd/γ-Al2O3催化剂, 在空速为50000 h-1时, 可使1%CH4-99%空气(体积分数)混合气中甲烷的10%转化温度降至254 ℃, 转化率100%时的转化温度降至340 ℃.

关键词: CeO2-MOx固溶体, Pd/γ-Al2O3催化剂, 甲烷催化燃烧, XRD, Raman, XPS

Abstract: Solid solution CeO2-MOx (M=La3+, Ca2+) promoted Pd/γ-Al2O3 catalysts were prepared by a deposition-precipitation method. The structural properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that Mn+ ions incorporated into CeO2 lattice and solid solutions formed in Pd/γ-Al2O3-CeO2-MOx catalysts. The formation of solid solution was confirmed by the change in lattice parameters of CeO2 and the shift of 2θ angles as compared with pure CeO2. A strain formed in the O2- sub-lattice of CeO2 was revealed by Raman analyses, which decreased the intensity of the Raman-active band at around 463 cm-1 owing to the F2g symmetric stretching of Ce—O bond. The appearance of a new band at 615 cm-1 (in the case of Pd/γ-Al2O3-CeO2-CaO) and a shoulder at 320 cm-1 (in the case of Pd/γ-Al2O3-CeO2-La2O3) was also confirmed. Ionic Pdδ+ species were formed in the catalysts, which exhibited higher binding energies (0.5-0.6 eV higher for Pd 3d5/2) than that of normal PdO. The catalysts showed high activity and stability for low temperature methane combustion. 10% and 100% conversions of methane could be obtained at temperatures of 254 and 340 ℃, respectively, over Pd/γ-Al2O3-CeO2-La2O3 catalyst under an hourly space velocity of 50000 h-1.

Key words: CeO2-MOx solid solution, Pd/γ-Al2O3 catalyst, Catalytic methane combustion, XRD, Raman, XPS

MSC2000: 

  • O643