Quantification of the active site density and turnover frequency for soot combustion with O2 on Cr doped CeO2
Quantification of the active site density and turnover frequency for soot combustion with O2 on Cr doped CeO2
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DOI：
10.1016/j.cattod.2011.03.057
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发表时间：
2011-10
期刊：
影响因子：
5.3
通讯作者：
Xin Li;Shaojie Wei;Zhaoliang Zhang;Yexin Zhang;Zhongpeng Wang;Qingyun Su;Xiyan Gao
中科院分区：
文献类型：
--
作者：
Xin Li;Shaojie Wei;Zhaoliang Zhang;Yexin Zhang;Zhongpeng Wang;Qingyun Su;Xiyan Gao
研究了掺铬ceo_2混合氧化物上的烟尘燃烧。采用x射线粉末衍射、n2吸附/解吸、x射线光电子能谱和程序升温还原H2对催化剂进行了表征。以烟灰为探针分子，采用等温厌氧滴定法对活性位点进行了定量。计算了周转率（TOF），并用其来评价活性。Cr/(Cr+Ce)比值在1-3at以内的样品。在反应速率和TOF值的基础上显示出活性的提高。活性位点由Ce-O-Ce组成，由于Cr的掺杂促进，活性位点比ceo2略高。与CeO2相比，% Cr导致TOF可检测到的降低。这是因为活性位点是由Cr-O-Ce组成的。负载的CrOxspecies与ceo2的强相互作用导致Cr2O3活性的增加。Fe对ceo2o对烟尘燃烧的促进作用比Cr更显著，强烈推荐TOF作为活性比较的基础。
The soot combustion on Cr-doped CeO2mixed oxides was studied. The catalysts were characterized by X-ray powder diffraction, N2adsorption/desorption, X-ray photoelectron spectroscopy and temperature-programmed reduction with H2. The active sites were quantified using isothermal anaerobic titrations with soot as the probe molecule. The turnover frequency (TOF) was calculated and used to evaluate the activity. The samples with a Cr/(Cr+Ce) ratio within 1–3at.% show an improved activity on the basis of reaction rates and TOF values. The active sites were determined to be composed of Ce–O–Ce species, which is a little more active compared with CeO2due to the promotion by the doping of Cr. Although the similar reaction rates were observed, the doping of 5 at.% Cr results in a detectable decrease of the TOF compared with CeO2. This is because the active sites are composed of Cr–O–Ce species. The strong interaction of the supported CrOxspecies with CeO2results in an increase in the activity of Cr2O3. The promotional effect of Fe to CeO2on soot combustion is more significant than that of Cr. The TOF is strongly recommended to be the basis of the activity comparison.