Effect of Ni content on catalytic oxidation of CO over NiO/CeO2 catalyst
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摘要: 以CeO2为载体,Ni为活性组分,采用球磨法制备了低温条件下性能较好的CO氧化NiO/CeO2催化剂。通过XRD、BET、H2-TPR、XRF和XPS等技术对催化剂进行了表征,考察了镍含量对催化剂结构和CO低温氧化性能的影响。结果表明,不同Ni/Ce比主要影响催化剂表面晶格氧空位的数量以及活性组分和载体之间的相互作用。其中,Ni/Ce物质的量比为1∶9时,催化剂表面氧空位数量较多,因此,表现出优良的催化性能。在反应温度为200 ℃、氧过量系数为5、气体总空速为60000 mL/(gcat·h)的条件下,CO转化率为99.2%。此外,与传统液相制备催化剂技术相比,球磨法具有污染小、成本低、易操作等特点,有利于节约能源。Abstract: The NiO/CeO2 catalytic materials were prepared with ball milling method using CeO2 as carrier and Ni as active component with good CO oxidation performance at low temperature. The catalysts were characterized by XRD, BET, H2-TPR, XRF and XPS. The effects of nickel content on the structure and low temperature oxidation performance of CO were investigated. The results show that the Ni-Ce ratio mainly affects the number of lattice oxygen vacancies and the interaction between the active ingredient and the carrier. Among them, When the Ni/Ce mole ratios is 1∶9, there are more oxygen vacancies on the surface of the catalyst, so it shows excellent catalytic performance. When the reaction temperature is 200 ℃, oxygen excess coefficient is 5 and the total space velocity is 60000 mL/(gcat·h), the CO conversion reaches 99.2%. In addition, compared with the traditional liquid phase catalyst preparation technology, ball milling has the advantages of low pollution, low cost and easy operation, which is beneficial to save energy.
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Key words:
- method of ball mill /
- CO oxidation /
- CeO2 /
- low temperature
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表 1 NiO/CeO2催化剂的XRD分析
Table 1 XRD data of NiO/CeO2 catalysts
Sample Cell parameter/nm Crystallite size of CeO2/nm CeO2 0.5410 22.0 NC-0.5 0.5408 21.9 NC-1 0.5399 20.9 NC-2 0.5409 20.8 表 2 NiO/CeO2催化剂的BET分析
Table 2 BET analysis of NiO/CeO2 catalyst
Sample SBET/(m2·g−1) Pore size/nm CeO2 24.3 9.49 CeO2 34.6 9.46 NC-0.5 36.1 12.85 NC-1 34.5 11.90 NC-2 32.3 9.18 表 3 NiO/CeO2催化剂的Ni元素含量
Table 3 Ni element content of NiO/CeO2 catalyst
Sample Target content of Ni/% Ni content/%a CeO2 − − NC-0.5 2.20 2.08 NC-1 4.06 3.76 NC-2 9.80 9.85 a: determined by XRF experiment 表 4 NiO/CeO2催化剂还原峰位置
Table 4 Location of reduction peak of NiO/CeO2 catalyst
Sample Location of reduction peak /℃ α β γ ε/ε, k/k, CeO2 − − − 500 833 NC-0.5 182 246 294 453 831 NC-1 180 223 294 455 824 NC-2 187 249 327 456 830 表 5 NiO/CeO2催化剂中晶格氧含量
Table 5 Lattice oxygen content in NiO/CeO2 catalyst
Catalyst Olat/(Olat+Oads)/% 0.5-NiO/CeO2 60 1-NiO/CeO2 77 2-NiO/CeO2 55 -
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