二氧化氯对NO和Hg的气相氧化性能的实验研究

Experimental Research on the Gas-phase Oxidation Properties of Chlorine Dioxide on NO and Hg

二氧化氯（Cl O2）的气相氧化性能是实现基于Cl O2预氧化的同时脱硫脱硝乃至脱汞的关键。通过实验研究了气相Cl O2对NO和Hg的氧化特性,考察了多种因素对Cl O2氧化性能的影响,并用量子化学理论对部分反应进行了机理分析。研究结果表明：气相Cl O2能有效氧化NO,当[Cl O2]/[NO]=0.8时,NO的氧化效率可达82%;气相Cl O2对NO具有较好的氧化选择性,Cl O2会优先氧化烟气中的NO,当氧化剂过量时,SO2的氧化效率才会迅速增大;温度是影响NO氧化效率的重要因素,在70~290℃范围内,NO的氧化效率随温度升高明显下降;烟气中SO2浓度越高,NO的氧化效率越低;O2和水蒸气对NO的氧化均有一定的促进作用;Hg可被Cl O2高效氧化为易于脱除的Hg2＋,[Cl O2]/[NO]仅为0.3左右时,Hg的氧化效率就可达86%,且随[Cl O2]/[NO]的增加还有继续增大的趋势。

The oxidation properties of gas-phase chlorine dioxide（Cl O2） is the key to simultaneous removal of SO2, NOxand mercury based on pre-oxidation by Cl O2. Its oxidation properties on NO and Hg was investigated by experiment. The influences of several factors were studied, and quantum chemical method was employed to analyze the mechanisms of the main reactions. Results show that gas-phase Cl O2 has strong oxidizing abilityon NO, and NO oxidation efficiency can reach 82% at [Cl O2]/[NO]=0.8. Gas-phase Cl O2 has an oxidation selectivity of NO, which means that obvious SO2 oxidation will not be found until NO trends to be completely oxidized. Temperature is a fatal factor influencing NO oxidation efficiency. In the range of temperature from 70 ℃ to 290 ℃, NO oxidation efficiency shows a significant degree of decreasing with the rising of temperature. NO oxidation efficiency decreases with the rising of the concentration of SO2, while oxygen and water vapor promote the oxidation of NO in varying degrees. Hg can be efficiently oxidized to Hg2＋ by Cl O2 for easily removal. Up to 86% oxidation efficiency of Hg can be seen at [Cl O2]/[NO] is merely 0.3, and the oxidation efficiency of Hg has a gradually upward trend with the increase of [Cl O2]/[NO].