温度对等离子体与催化剂结合脱除NO_x的影响

EFFECT OF TEMPERATURE ON THE CONVERSION OF NO_x IN PLASMAS AND CATALYST COMBINED SYSTEM

考察了温度对介质阻挡放电和CuZSM-5催化剂"一段法"结合脱除氮氧化物(NOx)的影响.实验表明,在250℃和300℃时,对于NO/N2,NO/O2/N2和NO/C2H4/N2三个体系,"一段法"脱除NOx的活性都相对较低.在NO/O2/C2H4/N2体系中,250℃介质阻挡放电和CuZSM-5结合脱除NOx产生了明显的协同效应.在300℃,等离子体对脱除NOx起负作用.相对低温(150℃)时,等离子体的促进作用很小.电学实验表明,当反应温度由25℃升至450℃,"一段法"体系的李萨如(Lissajous)图形由平行四边形(25℃)逐渐变为椭圆形(450℃),表明较高温度时催化剂的介电性质发生了变化.原位发射光谱证明在不同温度下,"一段法"体系中等离子体气相产生的活性物种数量明显不同.

The effect of temperature on dielectric barrier discharge （DBD） and CuZSM-5 catalyst combined system for NO, removal by using a one-stage reactor is investigated. The conversion of NO, by using a one-stage reactor in different gas composition has been studied. The conversion of NO, in NO/N2, NO/O2/N2 and NO/C2H4/N2 systems is low at 250℃ or 300℃. In NO/O2/C2 H4/N2 system, the significant synergistic effect between DBD and Cu（ 165 ）ZSM-5 combined system for NO, removal is observed at 250℃. At lower reaction temperature, 150℃, the enhancement of NO, conversion from the DBD plasma is small. At higher temperature, 300℃, the plasma exhibits a negative effect to the NOx conversion. Experimental result of the electric characteristics of one-stage reactor demonstrated that by increasing temperature from 150℃ to 450℃, the shape of Lissajous figure is changed from a parallelogram （25℃） to a more elliptic shape （450℃） . This implies that the electric characteristics of catalyst may be changed. In-situ optical emission spectra show the number of gas phase active species in the one-stage system can be changed with different reaction temperatures, room temperature and 250℃.