Low-temperature SCR Denitrification Performance Of Transition Metal Oxide (MnO X -CeO 2 ) Modified Copper-based Catalysts

The main technology of NOx removal is Selective Catalytic Reduction and the catalyst V2O5-WO3/TiO2 is mainly used in this method which requires the temperature window of 300 to 400?. Therefore the SCR denitration systems should be arranged in front of the air preheater and ESP in which area the flue gas with a large amount of dust will bring damages such as abrasion, corrosion, and hole blocking to the SCR device.It has become a research hotspots in the field of flue gas denitration to find a catalyst with the same denitration ability at lower temperature. Hence, the major objective of this article is to performing an experimental study on the preparation, characterization and performance of the catalysts based on the optimized formulation of copper-based catalyst modified by transition metal oxides (MnOx-CeO2). The conversion ability for Hg0 in the simulated flue gas were also investigated. In addition, the adsorption characteristics of the catalysts' surface was investigated by the electrochemical analysis method.The catalysts used in this article were prepared by a sol-gel method and characterized by means of BET, SEM and XRD techniques to have insight into physicochemical properties. The characterization results showed that the catalysts prepared by sol-gel method had great surface structure and pore characteristics; The introduction of MnOx decreased the specific surface area of the catalysts because of the crystallization of MnO2 while the introduction of CeO2 weakened this trend by improving the dispersion of MnOx; The introduction of MnOx-CeO2 inhibited the grain growth of ?-Al2O3 crystallite.Performance of the prepared catalysts were experimentally investigated in a fixed bed adsorption system at 100-200?. The results showed that the highest denitration efficiency was achieved on the catalyst of 6%CuO-5%MnOx-10%CeO2/?-Al2O3 under N2+6%O2+600ppmNO+600ppmNH3 atmosphere at 200?. Both H2O and SO2 had inhibition effect on SCR denitration efficiency.The efficiency decreased from 79.8% to 51.3% when the H2O content increased from 0 to 10%. When the SO2 content increased from 0 to 800ppm, the denitration efficiency decreased from 79.8% to 48.6%. O2 is a necessary condition for the SCR reaction and the denitration efficiency is only about 20% without O2. When the O2 content increases to 6%, the denitration efficiency can be stabilized at 70%-80%. The doping of CeO2 changed the valence state of Mn in MnOx due to the adsorption-desorption reversible cycle of lattice oxygen. The main existing form of Mn became MnO2 with the doping of CeO2 and MnO2 promoted the oxidation of NO to NO2, which was advantageous to improve the efficiency of SCR denitration. Also, the effects of the O2 on the denitration efficiency showed that the lattice oxygen supplemented by O2 so that the reaction can be carried out continuously.The results of mercury removal experiment showed that the introduction of Mn-Ce had an important influence on the catalysts and the highest mercury capture rate 46.5ug/g was achieved with 10%MnOx-5%CeO2 loading; O2 played an important role in the mercury removal by supplementing the lattice oxygen which consumed in the reaction; H2O and SO2 had an inhibition effect on mercury removal while NO was beneficial to it. The oxidation rate and capture rate of mercury decreased from 81.2%and 71.2% to 25.4% and 17.3% when the H2O content increased from 0 to 9%. When the SO2 content increased from 0 to 500ppm, the oxidation rate and capture rate of mercury decreased from 81.2% and 71.2% to 45.3% and 34.7%. Compared with the atmosphere without NO, the oxidation rate and capture rate of mercury were increased by 5.5% and 8.5% under the atmosphere of 600ppmNO.The (110) surface of y-Al2O3 was established by Materials Studio based on quantum chemistry theory. The Castep method was used to analyze and compare the adsorption condition of NO and NH3 on the (110) surface. The results showed that the adsorption of NH3 on ?-Al2O3 (110) surface is stronger than that of NO. The N atoms of NO was more likely to be adsorbed on the top of the O2c while the NH3 could form a stable adsorption on the top of the A1 atom.