Catalytic degradation of toluene over Cu-Mn-Ce-Zr/TiO2 coupled with low temperature plasma
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摘要: 以TiO2为载体, 采用等体积浸渍法制备了负载型CuxMn1-xCe0.75Zr0.25/TiO2(x=1.0、0.75、0.5、0.25、0)负载型催化剂, 采用XRD、H2-TPR、O2-TPD和XPS等方法对催化剂进行了表征, 并通过低温等离子体协同催化剂对大流量的甲苯模拟废气进行了催化降解反应研究。结果表明, Cu和Mn单主金属催化剂的活性优于Cu-Mn双主金属催化剂, 其原因是双金属催化剂中Mn的添加减弱了Cu与助剂Ce之间的相互作用, 使得催化剂的晶格氧减少, 低温还原性能降低。在反应初期, 甲苯降解主要依赖于催化剂的活性, 具有较好的低温还原性以及丰富的氧空穴和晶格氧含量的CuCe0.75Zr0.25/TiO2的活性最好; Mn具有较强的O3分解能力, 当等离子体比能密度(SED)增加到一定值后, 等离子体与催化剂的协同作用增强, 从而使得MnCe0.75Zr0.25/TiO2催化剂活性高于CuCe0.75Zr0.25/TiO2, 强化了甲苯的脱除。
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关键词:
- 低温等离子体 /
- Cu-Mn双金属催化剂 /
- 协同催化 /
- 甲苯降解
Abstract: A series of supported CuxMn1-xCe0.75Zr0.25/TiO2 (x = 1.0, 0.75, 0.5, 0.25, 0) catalysts were prepared by impregnation and characterized by XRD, H2-TPR, O2-TPD and XPS; the performance of CuxMn1-xCe0.75Zr0.25/TiO2 catalysts in the degradation of toluene coupled with low temperature plasma under high space velocity was then investigated. The results indicate that the composite catalysts with single Cu or Mn as the main active component exhibit higher activity than those with double Cu and Mn components; the addition of second component may weaken the interaction between Cu and Ce, leading to a decrease in the content of lattice oxygen and the reducibility at low temperature. The CuCe0.75Zr0.25/TiO2 catalyst exhibits superior performance for toluene oxidation in the initial reaction stage, owing to its high content of lattice oxygen and oxygen vacancies. With the increase of the specific energy density (SED) of low temperature plasma, the concentration of O3 increases and the MnCe0.75Zr0.25/TiO2 catalyst then displays higher activity in toluene degradation than CuCe0.75Zr0.25/TiO2, because of the prominent enhancement of synergistic effect between plasma and catalyst over the former MnCe0.75Zr0.25/TiO2 catalyst. -
图 1 等离子体协同催化降解甲苯评价装置示意图
Figure 1 Schematic diagram of low temperature plasma coupling with catalyst for toluene degradation
图 5 CuxMn1-xCZ/T催化剂的XPS谱图
(a): Cu 2p; (b): Mn 2p; (c): Ce 3d; (d): O 1s
Figure 5 XPS spectra of the CuxMn1-xCZ/T catalysts
图 6 催化剂甲苯降解率(a)和CO2选择性(b)与比能密度的关系
Figure 6 Toluene conversion (a) and selectivity to CO2 (b) for toluene degradation over various catalysts as a function of plasma specific energy density (SED)
表 1 CuxMn1-xCZ/T催化剂的表面物种
Table 1 Surface species of the CuxMn1-xCZ/T catalysts
Catalyst (Cu+Mn)/Ti(%) Ce3+/Ce4+ Olat/Oad CuCZ/T 2.00 0.35 5.86 Cu0.75Mn0.25CZ/T 2.58 0.31 2.06 Cu0.5Mn0.5CZ/T 2.58 0.31 0.68 Cu0.25Mn0.75CZ/T 2.52 0.31 0.73 MnCZ/T 1.60 0.25 4.91 
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表 2 CuxMn1-xCZ/T催化剂上甲苯转化率为99%时对应的SED值
Table 2 SED values at a toluene conversion of 99% over the CuxMn1-xCZ/T catalysts
Catalyst CuCZ/T Cu0.75Mn0.25CZ/T Cu0.5Mn0.5CZ/T Cu0.25Mn0.75CZ/T MnCZ/T SED /(J·L-1) 900 610 695 800 423
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