Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds: Part 2. Ozone decomposition and deactivation of γ-Al2O3
Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds: Part 2. Ozone decomposition and deactivation of γ-Al2O3
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DOI：
10.1016/j.apcatb.2004.11.024
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发表时间：
2005-06
影响因子：
22.1
通讯作者：
U. Roland;F. Holzer;F. Kopinke
中科院分区：
文献类型：
--
作者：
U. Roland;F. Holzer;F. Kopinke
臭氧在非热等离子体（NTP）和非均相催化两种不同配置中的作用进行了研究，即使用气相等离子体，随后将排放物暴露于填充床反应器中的催化剂（等离子体后处理）和将催化剂直接放置在放电区（等离子体内催化）。采用无孔和多孔氧化铝和二氧化硅作为模型催化剂。在两种操作模式下，研究了固定化碳氢化合物、甲苯（挥发性有机化合物）和一氧化碳（无机污染物）的氧化。虽然o3在γ-Al2O3上的催化分解可以充分解释催化后等离子体处理下碳氢化合物氧化的转化和选择性，但等离子体内催化的转化过程更为复杂，对其他三种材料（α-Al2O3、石英和硅胶）也有明显的氧化反应。很明显，由于在NTP中形成的短寿命物种，在等离子体催化的情况下，可以利用额外的协同效应。多孔氧化铝的臭氧分解能力与其对含碳剂的氧化活性相关。可以清楚地看到，反应产物co2毒害了γ- al2o3表面的催化位点。通过NTP处理可以部分恢复o3分解的催化活性。然而，在实际用途中，等离子体内催化过程提供的额外反应途径对于令人满意的转化和选择性是必不可少的。
The role of ozone was studied for two different configurations combining non-thermal plasma (NTP) and heterogeneous catalysis, namely the use of a gas phase plasma with subsequent exposure of the effluent to a catalyst in a packed-bed reactor (post-plasma treatment) and the placement of the catalyst directly in the discharge zone (in-plasma catalysis). Non-porous and porous alumina and silica were deployed as model catalysts. The oxidation of immobilised hydrocarbons, toluene as a volatile organic compound and CO as an inorganic pollutant were studied in both operational modes. While conversion and selectivity of hydrocarbon oxidation in the case of catalytic post-plasma treatment can be fully explained by the catalytic decomposition of O3on γ-Al2O3, the conversion processes for in-plasma catalysis are more complex and significant oxidation was also measured for the other three materials (α-Al2O3, quartz and silica gel). It became obvious that additional synergetic effects can be utilised in the case of in-plasma catalysis due to short-lived species formed in the NTP. The capability of porous alumina for ozone decomposition was found to be correlated with its activity for oxidation of carbon-containing agents. It could be clearly shown that the reaction product CO2poisons the catalytic sites at the γ-Al2O3surface. The catalytic activity for O3decomposition can be partially re-established by NTP treatment. However, for practical purposes the additional reaction pathways provided by in-plasma catalytic processes are essential for satisfactory conversion and selectivity.