Study On The Preparation And Application Technology Of The Low-cost Flue Gas Denitration Catalyst

Nitrogen Oxides?NOx?is considered as one of the major sources of air pollution around the world,which greatly contributes to the acid rain,greenhouse effect,ozone depletion,and photochemical smog,as well as direct damage to human respiratory system.Therefore the government has made more and more stringent emission standards in that it has seriously affected the living environment and quality of human beings.The selective catalytic reduction of NOx with NH₃ is widely recognized as the most effective technology for abating NOx from power plants,combustion facilities and vehicles.The extruded honeycomb V2O5-WO3?MoO3?/TiO2 catalyst has been widely used in power industries,which possesses good resistance to SO2 and H2 O with a relatively narrow temperature window of 300-400 ?.It is becoming the research hotspot and difficulty in the development of high de-NOx activity,lower cost,and non-toxic SCR catalyst and its application technology for the typical industrial combustion flue gas owing to the commercial V-W/Ti denitration catalyst exists some drawbacks such as high temperature activity,expensive raw material price and V2O5 hypertoxicity as well.At present,the main way to reduce the cost of SCR denitration catalyst is usually to adopt the preparation technology of surface-coating catalyst and choose cheap raw material for deNOx catalyst.For the low-dust and low-temperature flue gas from mid and mini-scale industrial boiler,the development of cheap deNOx catalyst with high low-temperature activity by coating method could greatly decrease the investment of deNOx project,showing promising industrial application prospect.In this work,the honeycomb deNOx catalyst was fabricated by coating the V2O5?4wt.%?-MoO3?4wt.%?-WO3?5wt.%?/TiO2 catalyst slurry on the cheap honeycomb substrate.The monolithic coating catalyst with thickness of 110 ?m showed nearly the same deNOx activity as the conventional extruded honeycomb catalyst.However,the usage of expensive active components only accounted for 12.8% raw material needed for the extruded catalyst,which significantly decreased the catalyst costs.The catalyst showed extraordinary SO2/H2O-resistant stability at 250 during the 100 h discontinuous test with excellent intensity and wearability.?The pilot test of the coating catalyst over the flue gas from glass kiln exhibited excellent deNOx performance with above 80 % NO conversion and less than 3 ppm NH₃ escape during the 1100 h stable test on the condition of 2800 mg/Nm3 inlet NOx concentration,240-300 and 7150 h?-1 GHSV.Based on waste control by waste,red mud was used as raw material through acid treatment,followed by deionized water washing to prepare the Fe-based metal oxides de-NOx catalyst,which was comparable with the traditional commercial vanadium catalyst.The structure characterization?XRF,XRD,SEM,TEM,BET,TG,XPS?revealed that the alkali/alkali-earth metal can be removed by the pretreatment,which also can enhance the uniformity of the distribution of red mud particles accounting for the improvement of the deNOx activity.More acidic ferric sulfate species were found by sulfurization causing the further increase of NO conversion?80%-100%?.It was found that the NH₃-SCR reaction on the red mud catalyst follow E-R mechanism by the analysis of H2-TPR,NH₃-TPD and in situ DRIFTS,on the other hand,the NH₃ adsorption was the control step.Moreover,the effects of alkali metal elements,SO2 and H2 O on the active sites and reaction properties have been investigated.