活性炭纤维吸附脱除NO过程中NO氧化路径分析

在小型固定床吸附实验台上开展了黏胶基活性炭纤维吸附脱除NO的实验研究。采用H₂O₂溶液浸渍以及热处理方法对活性炭纤维表面进行修饰,以获得表面孔隙结构接近而含氧官能团含量不同的样品;考察样品在惰性氮气气氛、含氧气氛下吸附脱除NO的效果,以及表面含氧含氮官能团的变化规律。探讨了含氧官能团在NO催化氧化过程中的作用及含氧气氛下O₂对于NO转化为NO₂的影响,分析了活性炭纤维表面吸附的NO向NO₂的主要转化途径。结果表明,在氮气气氛下活性炭纤维表面C-O官能团对吸附态的NO起到氧化作用,吸附态NO被C-O官能团氧化生成-NO₂官能团;在含氧气氛下活性炭纤维吸附NO后表面出现-NO₂、-NO₃官能团,通过长时间实验测定三种样品在含氧气氛下对NO吸附的效果,发现三种样品稳定时催化氧化效果一致,表明含氧官能团对初始NO的物理吸附影响较大,而对整个吸附过程影响较小。吸附在活性炭纤维表面上的NO与环境气氛中的游离态O₂发生氧化反应是NO转变为NO₂的主要途径。

Oxidation path analysis of NO in the adsorption and removal process using activated carbon fibers

The removal of NO by viscose base activated carbon fibers were carried out on a fixed-bed adsorption reactor.The methods such as hydrogen peroxide(H2O2) solution impregnation,heat treatment were employed separately to modify the activated carbon fibers.The NO removal efficiency was investigated using the activated carbon fibers before and after modification in the inert nitrogen atmosphere,oxygen-containing atmosphere.Furthermore,the change of activated carbon fibers characteristics,such as pore structure as well as nitrogenous or oxygenous surface functional groups,was also discussed in order to explore the effect of oxygen-containing functional groups and O2 in atmosphere on the NO catalytic oxidation and the transformation process of NO to NO2.The results show that in the nitrogen atmosphere the C-O functional groups of the activated carbon fiber surface can oxidize the adsorbed NO to be-NO2.On the other hand,in the oxygen atmosphere-NO2 and-NO3 are detected in the activated carbon fibers surface after the NO adsorbing.It is found that NO removal efficiency in stable stage after long time test is almost the same for the original activated carbon fibers as well as the two modified ones,which indicates that the transformation of NO to NO2 is mainly resulted from the reaction between the adsorbed NO on activated carbon fibers and the free oxygen in atmosphere.