NH3 In Flue Gas Research Articles

MIL-100(Fe) supported Mn-based catalyst and its behavior in Hg0 removal from flue gas

A novel magnetic composite catalyst of MnOx loaded on MIL-100(Fe) was prepared for the removal of Hg0 from flue gas, via incipient wetness impregnation followed with calcination at 300 °C. The MIL-100(Fe) supported catalyst showed greater capacity of Hg0 adsorption and oxidation than Fe2O3 supported catalyst at all test temperatures, showing Hg0 removal efficiency of 77.4% at 250 °C with high GHSV of 18,000 h−1. Besides the merit of high BET surface area and developed porous, the ultra-highly dispersed and homogeneous Fe sites on MIL(Fe) significantly promoted Hg0 adsorption and oxidation via the synergy effect with MnOx. Furthermore, the catalyst exhibited magnetic property, which allowed easy separation of the catalyst from fly ash with a recovery of 104%. SO2, H2O and NH3 in flue gas were proved inhibited Hg0 removal via different mechanisms. SO2 and H2O competed and desorbed Hg2+ on the surface of catalyst, while NH3 was more likely to compete adsorption sites with Hg0.

Influence factors and mechanism of selective catalytic reduction of NO in the flue gas over activated coke

ABSTRACT The aim of this study was to study the influence factors of selective catalytic reduction (SCR) of NO with NH3 in flue gas and to clarify the mechanism of SCR over activated coke (AC). An AC in various simulated flue gases for reduction of NO was examined in a fixed-bed reactor. X-ray photoelectron spectroscopy (XPS) was used to performhigh-resolution scanning of surface N element. The results indicate that the presence of O2 in flue gas facilitates the NO reduction in SCR. Higher polarity of H2O molecule may inhibit NH3 or NO adsorption on the surface of ACs, so that NO reduction has been restrained. A lowest NO conversion was tested at 250°C in the temperature range of 100–350°C, meaning that may presence of different SCR mechanism at low or high temperature. Adsorption of NH3 below 250°C is dominated by physical adsorption and adsorption of NH3 higher than 250°C is dominatedby the chemical reaction between NH3 and AC base on the determination of XPS and adsorption capacities of NH3. There was a good correlation between adsorption capacity of NH3 and NO conversion, which indicated that NH3 adsorption is a key step in SCR regardless of whether NH3 was physically or chemically adsorbed on the AC.

都市ごみ焼却施設における排ガス中のアンモニア自動計測器の特性

都市ごみ焼却施設における排ガス中のアンモニア自動計測器の特性

Carbon dioxide laser monitor for NH_3 in flue gas

An instrument was developed for the detection of NH3 in flue gas, exploiting a fortuitous spectral overlap between the ν2aQ(6,6) absorption line of NH3 and the R (18) emission line of the isotopic 13C16O2 laser. The system was developed for use with De–NOx processes, which convert harmful nitric oxides generated in utility and industrial furnaces into harmless nitrogen and water vapor by injection of NH3. The instrument detects unreacted NH3 in the flue gas down to concentrations of a few ppm with an accuracy of ∼10%. It can serve as an environmental monitor and as part of a feedback control system to adjust the upstream NH3 injection to the desired rate.

Life of V2O5-TiO2 Catalyst for the NOx Reduction with NH3 in Flue Gas from Oil Fired Boiler

The 12, 000h life test of the V2O5-TiO2 catalyst for reduction of NOx with NH3 has been investigated in real flue gases containing high concentration of SOx from oil-fired boiler on a pilot plant. Steady activities over 90% of NOx reduction were achieved for 12, 000h at 350°C (space velocity: 8, 000h-1). On the other hand, when the catalysts were taken out of the reactor in certain periods and examined by means of a laboratory reactor at 250-450°C, the activities of catalysts decreased with reaction time at lower temperatures (250-300°C) and higher temperature (450°C). It was observed that SOx in flue gas affected their catalytic activities than the other dust components. The characterization of used catalyst was also examined by means of X-ray photoelectron spectrometer.