Yi Li,Yanping Li,Pengfei Wang,Wenping Hu,Suge Zhang,Qiang Shi,Sihui Zhan
A series of MnFeO x nanorods with different Fe/Mn molar ratios were successfully synthesized by the hydrothermal method for low temperature selective catalytic reduction (SCR) of NO x with NH 3 . These MnFeO x catalysts have been systematically characterized by SEM, TEM, XRD and XPS. Furthermore, the MnFe (0.1) O x showed the highest catalytic performance with nearly 100% of NO x removal efficiency from 200 to 350 °C. On the basis of the TPR, BET and in situ DRIFT results, it can be found that the addition of Fe species induced a possible redox reaction process and increased the surface chemisorbed oxygen concentration and acid sites, which should be responsible for the enhanced SCR activity of MnFe (0.1) O x . Meanwhile, several important process parameters affecting NO x removal efficiency in NH 3 -SCR were carried out, such as time, H 2 O and SO 2 .
Zhitao Han,Bojun Liu,Shaolong Yang,Xinxiang Pan,Zhijun Yan
The experiments were performed in a lab-scale countercurrent spraying reactor to study the NOx removal from simulated gas stream by cyclic scrubbing using NaClO solution. The effects of NaClO concentration, initial solution pH, coexisting gases (5% CO2 and 13% O2), NOx concentration, SO2 concentration, and absorbent temperature on NOx removal efficiency were investigated in regard to marine exhaust gas. When NaClO concentration was higher than 0.05 M and initial solution pH was below 8, NOx removal efficiency was relatively stable and it was higher than 60%. The coexisting CO2 (5%) had little effect on NOx removal efficiency, but the outlet CO2 concentration decreased slowly with the initial pH increasing from 6 to 8. A complete removal of SO2 and NO could be achieved simultaneously at 293 K, initial pH of 6, and NaClO concentration of 0.05 M, while the outlet NO2 concentration increased slightly with the increase of inlet SO2 concentration. NOx removal efficiency increased slightly with the increase of absorbent temperature. The relevant reaction mechanisms for the oxidation and absorption of NO with NaClO were also discussed. The results indicated that it was of great potential for NOx removal from marine exhaust gas by wet scrubbing using NaClO solution.
The catalytic filter was fabricated by supporting selective catalytic reduction (SCR) catalyst on the low-density ceramic (LDC) for the removal of dust and nitrogen oxides (NOx) in the flue gases at relative low temperature. MnOx–ZrO2/TiO2 catalyst was selected as SCR catalyst. The NOx and dust removal efficiency, filter resistance, regeneration performance and anti-sulfur performance were investigated. The result showed that the NOx removal efficiency at 180°C reached 98.4% (1 m/min filtration velocity) for 6 wt% MnOx–ZrO2/TiO2 catalytic filter with Mn/Zr molar ratio of 2. Furthermore, MnOx–ZrO2/TiO2 catalytic filter performed good anti-sulfur performance. In the presence of 10 vol% water vapor and 100 ppm SO2 at 180 °C, the NOx removal efficiency for MnOx–ZrO2/TiO2 catalytic filter could retain up to 83.2% and it could recover to 91.8% when the water vapor and SO2 were cut off. MnOx–ZrO2/TiO2 catalytic filter showed the high dust removal efficiency of 99.99% and the low filter resistance of less than 200 Pa. The filter resistance of MnOx–ZrO2 /TiO2 catalytic filter could maintain 235.7 Pa after 200 times pulse blowback. The result illustrated that MnOx–ZrO2/TiO2 catalytic filter showed good regeneration performance.
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