PDF《船舶尾气中 NO 臭氧氧化研究》

第3卷第5期2008 年5月341 中国科技论文在线 SCIENCEPAPER ONLINE 船舶尾气中 NO 臭氧氧化研究 ――反应温度和尾气中碳氢化合物含量的影响 胡文佳,杨国华,周江华,于春令 (宁波大学海运学院,浙江宁波 315211) 摘要:用管式反应器试验研究了反应温度和[O3]/[NO]对臭氧氧化NO的影响.

结果表明,O3/N2/O2 体系在常 温、200 ℃和275 ℃下均不发生反应,N2 不能被O3 氧化;

在O3/NO/N2/O2 体系中,NO主要氧化为NO2,当[O3]/[NO]=1, 反应温度分别为常温和

200 ℃时, NO氧化率都达到 100%, 而在

275 ℃时, NO氧化率只有 72%, 表明反应温度影响显著,原因主要与较高温度下O3 分解加快有关.O3 在不同温度下的分解试验发现,O3 在常 温下分解很慢;

200 ℃时分解加快,在反应器中停留

9 s时,O3 的分解率为 59%,而275 ℃时分解更快,在反 应器中停留

9 s时,O3 的分解率为 80%.NO的氧化率与[O3]/[NO]成线形相关,C2H4 对NO氧化成NO2 有促进作 用.在[O3]/[NO] =0.6,反应温度分别为常温、200 ℃和275 ℃时,加入 400*10-6 C2H4, NO氧化率率由 61%、 62.6%和38.5%分别提高到 63.8%、63%和41%.C2H4 的促进机理,可能是O3 与C2H4 发生一系列反应生成强氧 化性的过氧自由基CH3O2 和HO2,这些自由基参与了NO的氧化反应. 关键词:环境工程学;

脱硝;

反应温度;

乙烯;

臭氧 中图分类号:U675 文献标识码:A 文章编号:1673-7180(2008)05-0341-6 Experimental study on oxidation of NO in ship exhaust by O3 ――The effect of reaction temperature and C2H4 content HU Wenjia,YANG Guohua,ZHOU Jianghua,YU Chunling (The Faculty of Maritime, Ningbo University, Ningbo, Zhejiang 315211) Abstract: The experiments were carried out in a tube reactor located in a tube furnace to investigate the influences of reaction temperature and [O3]/[NO] molar ratio on the oxidation of NO by O3. Results showed that no reaction was detected in O3/N2/O2 system at ambient temperature,

200 ℃ and

275 ℃,which confirms that N2 can not be oxidized by ozone to form nitrogen-oxides. In the O3/NO/N2/O2 system, NO was mainly oxidized to NO2. Almost 100% of NO was oxidized at both ambient temperature and

200 ℃, but only 72% at

275 ℃, under the same [O3]/[NO] ratio of 1. It indicates that the reaction temperature has a considerable influence on NO oxidation, i.e., faster decomposition of O3 occurs at higher temperature. The further tests show that decomposition rate of O3 was nearly zero at ambient temperature, but increased to 59% and 80% at

200 ℃ and

275 ℃ respectively, with 基金项目:浙江省自然科学基金项目(Y504013) 作者简介:胡文佳(1983-),女,硕士研究生 通信联系人:杨国华,教授,[email protected] 第3卷第5期2008 年5月342 resident time of

9 seconds in the tube reactor. In addition, the NO oxidation rate increased linearly with the increase of [O3]/[NO] ratio, and the introduction of C2H4 facilitates the conversion of NO to NO2. The addition of 400*10-6 C2H4 increased the yield rate of NO2 from 61%, 62.6% and 38.5% at ambient temperature,

200 ℃ and

275 ℃ respectively to 63.8%, 63% and 41% under the same [O3]/[NO] ratio of 0.6. It seems that the reactions between C2H4 and O3 produced some strong oxidative radicals such as CH3O2 and HO2, which could oxidize NO to NO2. Key words: environmental engineering;

denitrification;

reaction temperature;

C2H4;

ozone

1997 年国际海事组织(IMO)在IMO 总部伦敦召 开了MARPOL73/78 缔约国大会,批准了MARPOL73/78 公约的一个新增附则, 即附则 VI 《防 止船舶造成大气污染规则》[1~3] .该规则的出现,促 使各国必须降低柴油机废气 NOx 排放水平,这意味 着船舶必须装备废气净化设备.但目前还没有合适 的船舶废气净化设备可供选择.以尿素(氨)为还 原剂的选择性催化还原法(SCR)曾在