氧化锰八面体分子筛协同等离子体净化有机废气

发布时间：2018-10-30 16:55

【摘要】：低温等离子体催化技术是近年来兴起的一种治理废气的可行方法,与传统的治理废气方法和工艺相比具有投资和运行费用较低、处理效率较高、处理时间较短、易于控制等优点。国内外众多研究表明,利用等离子体技术处理大气污染的应用前景是十分广阔的。但低温等离子体技术反应器的选择、匹配和优化;相关催化剂的选择以及与反应器的结合;反应机理等方面还需要进一步深入研究,使其联合作用效果达到最佳,以利于大规模的工业化推广,为人类的环保事业做出贡献。氧化锰八面体分子筛(OMS-2)因具有多孔结构、混合价态的锰离子以及温和的表面酸碱性和优良的离子交换性,使其对污染物,尤其是挥发性有机污染物(VOCs)具有独特的去除效果,并且在适当的催化条件下转化率甚至可高达到100%。氧化锰八面体分子筛(OMS-2)的合成方法多种多样,不同的合成方法对其催化效率具有很大影响;而在其中掺杂金属离子在某些情况下可显著提高其对污染物质的转化率以及目标产物的选择性,特别是掺杂贵金属Ag、Pd等,效果更为优异。本实验将等离子体与OMS-2结合来去除VOC,其中VOC以甲苯为例作为典型代表,探究了不同制作方法对催化剂催化效率的影响;研究了不同的输入电压、能量密度、氧气含量等反应条件对去除效率的影响。得到在5%的氧气条件下,保持8kV左右的输入电压,可以获得相对最优的催化效率。随后采用回流法和水热法分别制作了不同Ag质量分数的Ag-OMS-2催化剂,在相对最优的条件下考察了其催化效率,并做了比较和对照。发现在现有实验条件下3%的Ag-OMS-2催化剂具有相对最优良的催化效率,而且回流法制得的催化剂普遍优于水热法制得的催化剂。实验还利用了一系列表征手段,如XRD和BET等,对各种不同方法制得的催化剂进行了表征。表征数据也应证了之前结论的正确性,为实验结论提供了有力佐证。而对低温等离子体催化分解污染物机理的研究和在低温等离子体氛围中OMS-2催化剂的使用寿命和处理不同污染物的适应性以及制作出更为优异的低温等离子体应用到催化工业型反应器依然是今后努力的方向和前进的路线。
[Abstract]:Low temperature plasma catalytic technology is a feasible method to treat waste gas in recent years. Compared with the traditional waste gas treatment method and process, it has lower investment and operation cost, higher treatment efficiency and shorter treatment time. The advantages of ease of control, etc. Many studies at home and abroad show that the application of plasma technology in the treatment of air pollution is very broad. However, the selection, matching and optimization of low temperature plasma reactor, the selection of relevant catalysts and the combination with reactor; The reaction mechanism and other aspects need to be further studied in order to achieve the best effect of joint action in order to promote large-scale industrialization and contribute to the environmental protection cause of human beings. Manganese oxide octahedral molecular sieves (OMS-2) have the properties of porous structure, mixed valence manganese ions, mild surface acidity and alkalinity, and excellent ion exchange properties, which make them treat pollutants. Especially the volatile organic pollutant (VOCs) has a unique removal effect, and the conversion rate can be up to 100 under the appropriate catalytic conditions. The synthesis methods of manganese oxide octahedral molecular sieve (OMS-2) are various, and different synthesis methods have great influence on the catalytic efficiency of MNO _ 2 octahedral molecular sieve (OMS-2). In some cases, doping metal ions can significantly improve the conversion of pollutants and the selectivity of target products, especially the doping of precious metal Ag,Pd, the effect is better. In this experiment, plasma and OMS-2 were combined to remove VOC,. Toluene was taken as a typical example of VOC, and the effect of different preparation methods on catalytic efficiency of catalyst was investigated. The effects of different input voltage, energy density and oxygen content on the removal efficiency were studied. The optimal catalytic efficiency can be obtained by keeping the input voltage of 8kV at 5% oxygen. Ag-OMS-2 catalysts with different mass fraction of Ag were prepared by reflux method and hydrothermal method respectively. The catalytic efficiency of the catalyst was investigated under the relative optimum conditions and compared with that of the control. It is found that 3% Ag-OMS-2 catalyst has the best catalytic efficiency under the existing experimental conditions, and the catalyst prepared by reflux method is generally superior to that obtained by hydrothermal method. A series of characterization methods, such as XRD and BET, were used to characterize the catalysts prepared by different methods. The characterization data should also prove the correctness of the previous conclusions and provide strong evidence for the experimental conclusions. The mechanism of catalytic decomposition of pollutants by low temperature plasma, the service life of OMS-2 catalyst in low temperature plasma atmosphere, the adaptability of treating different pollutants and the preparation of better low temperature plasma were studied. The application of catalytic industrial reactor is still the direction of future efforts and the way forward.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X701

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