【摘要】 采用吸附、程序升温脱附及氧化和发射光谱等技术研究了介质阻挡放电对气相和催化剂表面吸附乙烯的作用.实验表明,介质阻挡放电等离子体能脱附催化剂表面吸附物种(如CO2和H2O等),并引发表面化学反应生成新物种(如在等离子体作用下C2H4和O2生成CO2和H2O);改变催化剂表面积碳化合物结构,并降低其起燃点;引发气相中乙烯发生反应生成中间物种或碎片(如CN和CH等).在富氧体系NO/O2/N2中加入C2H4,能使介质阻挡放电等离子体和CuZSM-5"一段法"结合体系产生协同效应,提高NOx转化率.该协同效应的产生与等离子体在气相及催化剂表面引发化学反应,产生参与NOx还原反应的新稳态物种和短寿命高能活性物种有关.更多还原

【Abstract】 In order to understand the synergistic effects between dielectric barrier discharge (DBD) plasmas and catalyst in the one-stage plasma-over-catalyst (POC) system, effect of DBD plasmas on C2H4 in the gas phase and adsorbed on the CuZSM-5 surface has been studied by adsorption, temperature programmed desorption (TPD), temperature programmed oxidation (TPO) and emission spectral techniques. The results demonstrated that the species adsorbed on the CuZSM-5 surface (such as CO2 and H2O) could be partly desorbed by DBD plasmas, and in the meantime the new species could also be formed by plasma-induced surface reaction. The structure of the carbonaceous deposit over the CuZSM-5 was changed and the "light-off" temperature for coke direct combustion reaction lowered by plasma-over-catalyst-induced processes. Some short-lived active species could be formed from plasma-induced fragmentation of C2H4. NOx removal was tested by DBD plasmas or a POC reactor. Without addition of C2H4, NOx conversion percentage was only 8% by pure plasma-induced processes in NO/O2/N2 system. With addition of C2H4, the NOx conversion percentage was increased to 18%, and large quantities of NO2 and CO were generated. The NOx conversion percentage could be up to 79% using the POC reactor in C2H4/NO/O2/N2 system. The formation of some stable species and short-lived active species from plasma- and plasma-catalyst-induced processes may be responsible to the observed synergistic effects between the plasmas and catalysts in the one-stage POC system.更多还原