Effect of water vapor and hydrocarbons in removing NO/sub x/ by using nonthermal plasma and catalyst

Abstract

Removal of NO/sub x/ in flue gas was investigated by using nonthermal plasma with catalysts. In this experiment, flue gas contained 5%-15% water vapor and hydrocarbons, as well as nitrogen, oxygen, and carbon dioxide. Catalysts tested in this paper were copper- and sodium-coated zeolite (CuZSM-5, NaZSM-5) and a conventional three-way catalyst (Pt-Rh, alumina cordierite). The simulated flue gases had from 0% to 15% water vapor, 70% NO removal was achieved with NaZSM-5 catalyst at 200/spl deg/C-500/spl deg/C, with 10% moisture and the power to the reactor turned off. High-temperature removal of NO/sub x/ was the result of plasma chemical reactions and adsorption in the catalyst. However, nonthermal plasma degrades the NO/sub x/ removal with CuZSM-5 catalyst, when the gas temperature is 300/spl deg/C or above. When the gas temperature was 100/spl deg/C, the nonthermal plasma process was enhanced by the combination of nonthermal plasma with any type of catalyst. The catalysts investigated in this paper do not work at lower temperatures by themselves. Adsorption characteristics were also investigated and only NaZSM-5 catalyst showed significant adsorption.