CuO在CeO_2和γ-Al_2O_3上的表面性质及对NO+CO反应性能的研究

Studies on the surface properties of CuO supported on CeO_2 and γ-Al_2O_3 and its reaction properties for NO+CO reaction

在色谱-微反实验装置上考察了CuO/CeO2、CuO/γ-Al2O3及CeO2改性的催化剂对NO+CO的反应性能,并用TPR、XRD、XPS、BET和NO-TPD等技术对上述催化剂进行了表征.结果表明催化剂活性的提高与铜物种在两种载体(CeO2和γ-Al2O3)上的价态(Cu2+和Cu+)、分散状态和吸附特性有关.TPR实验显示CuO在CeO2上存在两种还原物种,而在γ-Al2O3上只有一种还原物种.XPS检测表明CuO/CeO2的Cu2p3/2结合能值与Cu2+和Cu+的标准结合能基本吻合,而CuO/γ-Al2O3的Cu2p3/2结合能值接近或略低于Cu2+的标准结合能.NO-TPD实验表明催化剂表面的NO脱附峰温低于载体表面的NO脱附峰温,而CuO/CeO2表面的NO脱附峰温低于CuO/γ-Al2O3表面的NO脱附峰温,说明NO在CuO/CeO2表面的分解活性大于CuO/γ-Al2O3,而NO在催化剂表面的分解活性大于载体.

Reducibility and characteristics of CuO/CeO2, CuO/γAl2O3 and ceriamodified CuO/γAl2O3 catalysts were examined by using a microreactorGC NO+CO reaction system, BET, XRD, TPR, XPS and NOTPD methods. The results showed that the increase in catalytic activities is probably due to the presence of the copper oxide species with low valence,surface dispersion state and adsorption property. Two TPR reduction peaks were observed for CuO loading on CeO2, one TPR reduction peak was observed for CuO loading on γAl2O3; XPS data showed that the Cu2p3/2(eV) binding energy of CuO/CeO2 was similar to the standard binding energy of Cu2+ and Cu+; Whereas the Cu2p3/2(eV) binding energy of CuO/γAl2O3 was the same as or lower than the standard binding energy of Cu2+. The NOTPD profile also showed that the peak temperatures of NO desorption from the catalysts are lower than that from the supports and that the peak temperatures of NO desorption from the CuO/CeO2 are lower than that from the CuO/γAl2O3, indicating that the decomposition activity of NO on the catalysts is higher than that of on the supports.