络合-氧化-还原耦合方法脱除烟气中NOx的研究

NO与Fe2+反应生成络合物[Fe(NO)]2+易被O2氧化解络形成NO2-和NO3-离子,进而被尿素溶液还原生成N2.基于上述反应原理,本文提出脱除烟气中NOx的新方法,即以FeSO4为吸收液、O2为氧化剂、尿素为还原剂的络合-氧化-还原耦合法.考察了尿素初始浓度、吸收液pH值、NOx初始浓度、烟气流量等因素对NOx脱除率的影响.结果表明,尿素初始浓度越高、吸收液pH值越低、NOx初始浓度越大、烟气流量越小时,NOx脱除率越高;当尿素初始浓度为1.19mol/L,吸收液pH值为3.2,NOx初始浓度为1493mg/m3以及烟气流量为800mL/min时,反应初期(0~6min)NOx脱除率可达92%以上,且反应1h后脱除率仍可保持在69%左右.

Removal of NOx in flue gas by complexation-oxidation-reduction coupling method

[Fe(NO)]2+ formed by the complexation between NO and Fe2+ was easily oxidized by O2 to NO2- and NO3-. Furthermore, NO2- and NO3- were reduced to N2 by urea in solution. Based on these reactions, we developed a new method for removing NOx in flue gas, i.e., complexation-oxidation-reduction method in which ferrous sulfate solution, oxygen and urea were selected as complex agent, oxidant and reductant respectively. Effects of some factors including initial concentration of urea, pH value of absorbing solution, initial concentration of NOx and flow rate of flue gas on removal rate of NOx in flue gas were investigated. Results showed that the removal rate of NOx was positive correlation with the initial concentration of urea and the initial concentration of NOx, but negative correlation with the pH value of absorbing solution and the flow rate of flue gas. When initial concentration of urea, pH value of absorbing solution, initial concentration of NOx and flow rate of flue gas were 1.19mol/L, 3.2, 1493mg/m3and 800mL/min respectively, the removal rate of NOx was more than 92% in the initial stage (0~6min) and this removal rate still maintained about 69% after treatment of NOx for an hour.