Effect of Dy and Y doping on the catalytic performance of CuO/CeZrO2 for the preferential oxidation of CO in H2-rich stream
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摘要: 采用水热-浸渍法制备了系列Dy和Y掺杂改性的CuO/CeZrO2催化剂, 使用X射线粉末衍射(XRD)、N2吸附脱附和程序升温还原(H2-TPR) 等手段对催化剂进行了表征, 研究了Dy和Y掺杂改性对CuO/CeZrO2在富氢气氛中CO优先氧化催化性能的影响。结果表明, 所制备的CuO-CeZrO2催化剂均为萤石结构; 添加适当比例的Dy2O3和Y2O3能增强活性组分与载体间的相互作用, 有利于CuO活性组分的分散和低温还原能力的提高, 从而改善了CuO/CeZrO2用于CO优先氧化的催化活性。同时, 掺杂Dy和Y能够提高CuO/CeZrO2催化剂的抗CO2抑制作用的能力, 改善其催化稳定性。Abstract: CuO/CeZrO2 catalysts doped with different amounts of Dy2O3 and Y2O3 were prepared by the hydrothermal-impregnation method and characterized by XRD, H2-TPR and nitrogen sorption; the effect of Dy and Y doping on the catalytic performance of CuO/CeZrO2 for the preferential oxidation of CO in H2-rich stream was investigated. The results indicate that all the CuO/CeZrO2 catalysts have a fluorite structure; doping with appropriate amounts of Dy2O3 and Y2O3 can improve the interaction between the active component and support, the dispersion of CuO and its reducibility at low temperature, which is effective to enhance the activity of Dy and Y doped CuO/CeZrO2 catalysts in the preferential oxidation of CO. Moreover, the doping with Dy2O3 and Y2O3 can also reduce the inhibition effect of CO2 on CuO/CeZrO2 in CO oxidation and then improve its catalytic stability.
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Key words:
- CuO /
- CeZrO2 mixed oxide /
- preferential oxidation of CO /
- H2-rich stream /
- Dy2O3 /
- Y2O3
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图 3 CO转化率和CO2选择性随温度的变化
Figure 3 CO conversion and CO2 selectivity along with temperature for the preferential oxidation of CO in H2-rich stream over various CuO/Ce-Zr-RE-O2 catalysts
(the reactions were carried out at atmospheric pressure in a N2-balanced stream containing 1% CO, 1% O2 and 50% H2, with a GHSV of 40 000 mL/(gcat·h)) ■: CZD1; ●: CZD3; ▲: CZD5; ▼: CZY3; ◆: CZY5; ◀: CZY7; ▶: CZ
图 4 CO2对催化剂CO转化率和CO2选择性的影响
Figure 4 Effect of CO2 on CO conversion and CO2 selectivity for the preferential oxidation of CO in H2-rich stream over various CuO/Ce-Zr-RE-O2 catalysts (The reactions were carried out at atmospheric pressure in a N2-balanced stream containing 1% CO, 1% O2, 50% H2 and 15% CO2, with a GHSV of 20 000 mL/(gcat·h))
■: A-without CO2; ●: A-adding CO2; ▲: B-without CO2; ▼: B-adding CO2; ◆: C-without CO2; ◀: C-adding CO2; A=CZ; B=CZD1; C=CZY3
图 5 催化剂CZ、CZD5和CZY5的稳定性能
Figure 5 Stability test of the CZ, CZD5 and CZY5 catalysts for the preferential oxidation of CO in H2-rich stream over various CuO/Ce-Zr-RE-O2 catalysts (reactions were carried out at atmospheric pressure and 120 ℃ in a N2-balanced stream containing 1% CO, 1% O2 and 50% H2, with a GHSV of 40 000 mL/(gcat·h))
表 1 CuO/Ce-Zr-RE-O2催化剂的晶粒粒径、比表面积、孔径和孔容
Table 1 Crystallite size, BET surface area, pore diameter and pore volume of various CuO/Ce-Zr-RE-O2 catalysts
Sample 2 θ/(°) Interplanar spacing d/nm Crystallite size dCeO2(111) /nm ABET/(m2·g-1) Pore diameter d/nm Pore volume v/(cm3·g-1) CZ 28.94 0.308 3 8.51 130.5 6.31 0.265 CZD1 28.48 0.313 2 9.98 107.5 10.96 0.405 CZD3 28.64 0.311 4 10.18 99.4 8.35 0.288 CZD5 28.52 0.312 7 9.28 107.9 6.86 0.246 CZY3 28.93 0.308 0 8.53 127.1 5.64 0.256 CZY5 28.72 0.310 6 8.22 133.3 5.99 0.270 CZY7 28.88 0.308 9 9.11 119.3 8.10 0.330 dCeO2 (111) : calculated from Scherrer equation -
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