Direct Decomposition of NO Activated by Microwave Discharge

Abstract

The environmentally friendly removal of NO has been investigated using continuous microwave discharge (CMD) at atmospheric pressure. In these experiments, conversions of NO to N 2 as well as NO 2 were mainly observed for both dry and wet feed gas, which showed a great difference from those observed with other discharge methods. The effects of a series of reaction parameters, including microwave input power, O 2 concentration, NO concentration, and gas flow rate, on the product distribution and energy efficiency were also studied. Under all reaction conditions, the conversions of NO to N 2 were higher than those to NO 2 . The highest conversion of NO to N 2 was 88%. The reaction rate of NO removal and the effects of the different discharge modes on NO conversion and product distribution are also discussed. Through comparison of the results of different discharge modes, it was found that the addition of CH 4 apparently increased the conversion of NO to N 2 as well as the energy efficiency. A possible reaction process is suggested.

Reducing nitric oxide into nitrogen via a radio-frequency discharge

“…Besides N 2 , several to tens ppm of N 2 O were detected, but no NO 2 . Similar products were obtained by using microwave discharge [16,21]. When oxygen was added, it did not change F N 2 significantly.…”

“…However, η NO was 4.4-7.9% less at [O 2 ] = 2% and 12. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].3% less at [O 2 ] = 6% than at no oxygen (NO/N 2 ) condition at 30-120 W. This is because O 2 molecules attached to the energetic species, resulting in a significant decrease in the vibrational temperature of N 2 [15]. Moreover, the O 2 -added can be excited or dissociated into O radicals, which increases the rate of NO recombination.…”

Microwave Irradiation Coupled with Physically Mixed MeOx (Me=Mn, Ni) and Cu‐ZSM‐5 Catalysts for the Direct Decomposition of Nitric Oxide under Excess Oxygen

“…The microwave technique has been applied to heterogeneous catalysis research in the past decade. [20][21][22][23][24][25][26][27][28][29][30][31][32] There are some studies that use the microwave technique to enhance the chemical reaction for NO removal by the microwave-discharge method, [33][34][35] such as the SCR of NO by CH 4 over Fe/HZSM-5, [33] the decomposition of NO activated by microwave discharge with no catalyst, [34] the reduction of NO by CH 4 over Co-HZSM-5, [35] and the microwave-assisted reduction method, [36][37][38][39][40] such as Fe/Ga-5A zeolite as a catalyst and NH 4 HCO 3 as a reducing agent, [36] and microwave-induced reactions of nitrogen oxides and pyrolytic carbon matrix. [37] In addition, our previous study reported the microwave catalytic reduction of NO into N 2 by Mn 2 O 3 supported on active carbon (AC) at low temperature under excess oxygen.…”

Photochemical removal of NO2 by using 172-nm Xe2 excimer lamp in N2 or air at atmospheric pressure

“…Removal of NOx was also studied by using pulsed corona discharge [6][7][8][9][10][11][12][13] and microwave discharge methods [14][15][16][17][18][19][20][21][22][23]. Discharge methods will become a low cost convenient method, if NOx can be removed without using any catalysts and reducing agents.…”