HNO_(3)改性促进活性炭低温脱硝机理的研究

Effects of HNO_(3) modification on the mechanism of low temperature NO reduction over activated carbon

为了研究HNO_(3)改性对活性炭(AC)低温脱硝机理的影响,采用HNO_(3)在不同温度下对AC进行改性处理,改性前后样品在30−250℃进行脱硝活性测试,通过程序升温脱附(TPD)和瞬态响应实验对脱硝机理进行分析。结果表明,AC上NO转化率随反应温度升高逐渐降低再趋于稳定,反应物的吸附是速率控制步骤。含氧基团增加促进了NH_(3)的吸附,但这部分吸附态NH_(3)在30℃时几乎不参与反应,随反应温度升高不同程度活化,在30−90℃反应物的吸附是速率控制步骤,90℃后吸附态NH_(3)的活化是速率控制步骤。

To study the effects of HNO_(3) modification on NO reduction over activated carbon(AC)at low temperatures,the AC was modified using HNO_(3) at different temperatures.The activity of the resulted activated carbons towards NO reduction with NH_(3) was investigated in a temperature range of 30−250℃.The temperature programmed desorption(TPD)and transient response experiments were used to study the mechanism of NO reduction.The results reveal that the NO conversion decreased with temperature at the initial stage and then kept stable.The adsorption of reactants was the rate-determining step.The increase of oxygen groups on the catalyst surface enhanced NH_(3) adsorption.The adsorbed NH_(3) hardly reacted with NO at 30℃.With increasing temperature,the adsorbed NH_(3) was gradually activated.In the temperature range of 30−90℃,the adsorption of reactants was rate-determining step of NO reduction.When the temperature was higher than 90℃,the reaction was dominated by the activation of adsorbed NH_(3).