Preparation And Properties Of Manganese - Based Oxide Denitration Catalyst

In recent years, with the rapid development of economy, environment has also been great pollution. Air pollution becomes the problems to be solved in time. Nitrogen oxide is one of the main pollution sources of air pollution, and it is the main source of industrial emissions and motor vehicle exhaust emission. In the conditions of sufficient oxygen selective catalytic reduction is one of the effective methods to eliminate the nitrogen oxide pollution. The low-temperature SCR technology can make the SCR unit followed by the electrostatic precipitator and desulfurizer, which could reduce dust scour and poisoning of catalyst and prolongs the catalysts life greatly, thus reduce the operation cost. The activity of the low temperature SCR catalysts is not high and SO2poisoning resistance is poor are the main problems of low temperature SCR technology. In this paper aiming at the deficiency of SCR catalysts and combining the current research status, the system study on the catalyst of metal oxide MnOx as the main active component.This paper prepared MnOx-CeO2/TiO2catalyst using anatase type TiO2as catalyst carrier and use manganese nitrate and cerium nitrate as precursor, and then impregnate it. The performance of catalysts was investigated in a catalytic fixed reactor, the effect of active component loads doping amount and the calcination temperature and calcination time and carrier molding on the catalytic activity. The results showed that under the experimental conditions of catalyst loading quantity of2mL, GHSV20000h-1,5%O2(volume fraction), NO concentration750×10-6,[NH3]/[NO] ratio1.0, N2as the carrier gas, when Mn loading was15%(mass fraction), MnOx-CeO2/TiO2calcined at500℃along with5h, carrier selection type anatase TiO2powder could yield the well denitration effect. Its catalytic activity would be about75%NO conversion at100℃,120℃～180℃temperature range, the NO conversion rate of more than92.5%.The characterizations of SEM, XRD, BET, XPS,TPR and TPD was explored to analyze the surface morphology, surface chemical structure, specific surface area, electronic structure, reduction performance, and surface acidity of catalysts. The results showed that catalyst particles composed of nanoparticles, the average particle size of around50nm, by many nanoparticles reunion together constitute the loose structure of the catalyst. Attached to reunite the tiny particles of body surface is oxide active component of catalysts. The master of catalyst sharp titanium type of TiO2, active substances in amorphous state distribution in the surface of carrier and highly fragmented and TiO2carrier for anatase type catalyst will have higher NO removal rate.The stability of catalyst was tested for the MnOx-CeO2/TiO2, and the results show that the catalyst for the NO conversion rate in the1h by the initial94.9%to90%. Catalyst NO conversion rate has been slight fluctuations near90%for the next10h, there is no downward trend. SO2resistance test of catalyst was carried out in the flue gas containing200ppm SO2, and the results showed that the presence of SO2almost does not affect the denitration catalyst activity when temperature lower than100℃. The SO2evidently affects the activity of the catalysts when temperature above100℃, the basic catalyst for NO conversion to keep the level of around65%range180℃to220℃.SO2resistance explorative study is made by doping of metal elements, Y, Co, La oxide to MnOx-CeO2/TiO2catalyst. Studies showed that doping oxide of Y, Co and La to would improve catalyst high temperature sulfur resistance in above160℃. For under160℃or so, with these elements, the activity of catalyst instead of reduced. The sulfur resistance ideal experiment MnOx-CeO2-Co(0.01)/TiO2catalyst was prepared, the catalyst is still in relatively wide temperature range has high catalytic activity in the presence of200ppm SO2in flue gas, its denitration rate always stay at the levels of more than76%in the range of120℃～190℃.