等离子体在同时去除NO_x和碳烟催化反应中的作用

The Effects of Plasma on Simultaneously Catalytic Removal of NO_x and Soot

采用程序升温反应(TPR)技术,研究了等离子体辅助同时催化去除富氧柴油机尾气中NOx和碳烟(soot)的反应特性.研究结果表明,等离子体提高了同时去除NOx-soot的催化反应活性,降低了碳烟的燃烧温度,使碳烟起燃温度从300℃降到280℃,燃尽温度从425℃降到380℃;同时,等离子体辅助提高了NOx转化为N2的效率,使催化选择性从1.12%提高到1.53%.本文还分别研究了在NO和O2的环境中,有或没有等离子体作用下,碳烟在催化作用下的去除特性.等离子体作用使得NO在和O2共存、只有NO和只有O2存在的各种条件下,碳烟的催化燃烧活性都有不同程度的提高,促进了N2的生成.此外,本文也对等离子体辅助同时催化去除NOx-soot的机理进行了探讨.

The simultaneous removal of NO. and soot was studied by the temperature program reaction (TPR) technology over La0.8K0.2MnO3 catalyst assisted by plasma. When the experiment was carried out by catalysis process, the results showed that La0.8K0.2MnO3 catalyst had the excellent catalytic performance for the reduction of NO, by soot in the oxygen rich atmosphere. When the experiment was conducted by catalysis with the assistant of plasma in the same gases condition, the results showed that plasma improved the catalytic activity for simultaneous removal of NO. and soot, and reduced the combustion temperature of soot. As a consequence, the ignition temperature of soot was reduced from 300 degrees C to 280 degrees C, and the burning out temperature was also decreased from 425 degrees C to 380 degrees C. The conversion efficiency of NOx to N-2 was improved by plasma, and the selectivity to N-2 formation was enhanced from 1.12% to 1.53%. In addition, the catalytic property for soot removal was studied at various gas compositions with or without plasma. The results also showed that plasma improved the catalytic activity for the combustion of soot and the conversion efficiency of NOx to N-2 whether in the NO + O-2 or NO atmosphere. Also, the mechanism of plasma-assisted catalysis for simultaneous removal of NOx and soot was discussed in this paper.