不同尺寸反应器内H_2O_2热分解氧化NO特性与氧化产物分析

Characteristics and product generation pathway of NO oxidation by H_2O_2 thermal decomposition in different size reactors

采用实验方法研究了不同尺寸滴管炉反应器内H_2O_2热分解氧化NO特性。对比了不同H_2O_2蒸发条件对NO氧化率的影响规律。分析了气体温度、H_2O_2溶液浓度、H_2O_2:NO摩尔比、NO初始浓度及气体流量对NO氧化率的影响。检测了氧化产物并分析了产物的生成路径。结果表明:H_2O_2的快速蒸发是其热分解氧化NO的前提。减小H_2O_2液滴尺寸或液膜厚度可加速H_2O_2蒸发与分解,提高NO氧化率,扩宽NO氧化的温度范围。保证蒸发速率可削弱H_2O_2浓度对NO氧化率的影响。当H_2O_2:NO<10时,NO氧化率随H_2O_2:NO的增加而增加;当H_2O_2:NO>10时,NO氧化率几乎不随H_2O_2:NO变化。H_2O_2热分解对于较高浓度的NO具有更高的氧化效率。H_2O_2热分解氧化NO的主要产物为NO_2。HO_2·直接将NO氧化为NO_2,·OH则先将NO转化为HONO,然后进一步氧化为NO_2。

Characteristics of NO oxidation by H2O2 thermal decomposition in different size reactors in drop tube furnaces were studied.The effects of different H2O2 evaporation conditions on NO oxidation ratio were compared.The effects of gas temperature,H2O2 concentration,H2O2:NO,initial NO concentration and gas flow rate on NO oxidation ratio were analyzed.The oxidation product was detected and the generation pathway of the product was analyzed.The results showed that the rapid evaporation of H2O2 was the precondition for NO oxidation by H2O2 thermal decomposition.Reducing H2O2 droplet size or liquid film thickness could accelerate H2O2 evaporation and decomposition rate which enhanced NO oxidation ratio and broadened the NO oxidation temperature range.Ensuring the evaporation rate of H2O2 decreased the effect of H2O2 concentration on NO oxidation.When H2O2:NO<10,the NO oxidation ratio increased with the increase of H2O2:NO;when H2O2:NO>10,the NO oxidation ratio did not change with it.H2O2 thermal decomposition had higher oxidation efficiency for high concentrations of NO.The main product of NO oxidation by H2O2 thermal decomposition was NO2.HO2·directly oxidized from NO to NO2.However,·OH converted NO to HONO firstly,and then further oxidized HONO to NO2.