反应条件对等离子体脱除吸附于Cu-Ce/AC表面NO_x的影响

Effect of reaction conditions on removal of adsorbed NO_x over Cu-Ce/AC by plasma

以放电等离子体协同催化法对吸附在Cu-Ce/AC上的NO_x进行脱除,研究了不同的放电条件和添加水蒸气对脱除NO_x的影响。结果表明,对于同轴圆筒形反应器,催化剂量一定时,放电长度增加,吸附态NO_x去除率先升高后下降;放电电压增大,吸附态NO_x去除率升高,原因在于放电反应区内能量密度和活性粒子分布状态改变。根据NO_x程序升温脱附(TPD),TPD低温位(<200℃)的吸附态NO_x更容易被放电等离子体脱除,放电长度和放电电压能够影响不同吸附位上NO_x的去除效率。适宜条件下,吸附态NO_x去除率最高达到93.3%。循环吸附-等离子体脱除NO_x进行10次后,NO_x脱除率在92%以上。在混合气中添加5%水蒸气提高了等离子体对吸附态NO_x的去除率,但导致循环吸附-等离子体脱除NO_x效率下降。原因是H2O与NO_x竞争吸附带来的负面效应大于等离子体中H2O提供自由基与吸附态NO_x反应所带来的正面效应。

Research was conducted on plasma-discharge-assisted catalytic conversion of adsorbed NO_xover Cu-Ce/AC. The effects of different discharge conditions and water vapor on NO_xremoval were investigated. Results showed that for the coaxial cylindrical reactor with a fixed catalyst,adsorbed NO_xremoval increased and then decreased as discharge length increased. When discharge voltage increased,adsorbed NO_xremoval increased. This was related to the energy density and active species dispersion in the discharge reaction. According to NO_xtemperature-programmed desorption（ TPD）,the adsorbed NO_xover low-TPD（ 200 ℃） sites could be converted more easily. Discharge length and voltage could affect removal of NO_xover different adsorptive sites.The removal of adsorbed NO_xreached 93. 3% under proper conditions. In ten adsorption and plasma cycles,NO_xremoval was higher than 92% each time. Five percent water vapor improved adsorbed NO_xremoval in plasma,but led to a decrease in de-NO_xefficiency in adsorption-plasma cycles owing to competitive adsorption between H2 O and NO_x. The negative effect caused by competitive adsorption was more significant than the positive effect caused by the discharge reaction of adsorbed NO_xand radicals produced from H2 O.