Study On Performance Of V/Cu/Ce Composit Catalyts For Removal Of NO

Nitrogen oxide is one of the main pollutants in the atmosphere. About 90% NOx come from fossil fuel combustion and 95% of which is NO. In this work, the followings research works on the removal of NOx in the flue gas were conducted.1. On the basis of previous experiments of our research team, TiO2-SiO2 (TS) composite supports were prepared byco-precipition method; and impregnation method was adopted to prepare catalyst CuSO4-CeO2/TS catalysts. The resistance to SO2 and H2O poisoning of CuSO4-CeO2/TS catalysts in NH3-SCR system at low temperature was investigated. The results showed that at low temperature the activity of the catalyst sharply decreased because of H2O in the feed gas, but this effect could be mostly ignored when the reaction temperature is above 220℃. At this temperature SO2 (350ppm) was added and about 10 hours later there was a slight rise in conversion of NO. The catalyst was put into other activity test at 220℃with H2O (10%) and SO2 (350ppm). The conversion of NO had been keeping around 90% for 37 hours, then decreased quickly. The deactivated catalyst did not fully recover its activity by 4-hour thermal treatments at 350℃and 400℃. SiO2 in TiO2-SiO2 support prepared by co-precipitation method can suppresses the transformation of SO2 to SO3, which greatly alleviates the formation of ammonium sulfate and the sulfating of CeO2 on surface of CuSO4-CeO2/TS catalyst and enhance the resistibility to the combined effect of SO2 and H2O.2. NO in flue gas can be partly oxided into NO2 by the oxygen in flue gas with the promotion of catalyst. When the oxidation degree of NOx is up to 50%-60%, SO2 and NOx can be absorbed by FGD at the same time.Mn-Ce/Ti-PILCs, V2O5-WO3/TiO2, V2O5-Co3O4/TiO2, V205-NiO/TiO2 and V2O5-Bi2O3/TiO2 catalysts for NO oxidation were prepared in this work and their activities were investigated. Experimental results showed that when the reaction conditions were at temperature 300℃, space velocity 9000h-1, NO 500ppm, O2 10% and balanced with N2, Mn-Ce/Ti-PILCs produced conversion ratio of NO was up to 50%, which can meet need of wet absorption. The catalyst showed a good resistance to H2O. But the conversion ratio of NO declined quickly when there was SO2 in the feed gas. The deactivatied catalysts can only partly recovered its activity by thermal regeneration.V2O5-WO3/TiO2, V2O5-Co3O4/TiO2, V205-NiO/TiO2 and V205-Bi2O3/Ti02 have ability to transform NO to NO2 at low temperature. The activity of V2O5-WO3/TiO2 increased as the reaction temperature rised, When the reaction conditions were at temperature 286℃, space velocity 9000h-1, NO 700ppm, O2 10% and balanced with N2, conversion ratio of NO was up to 40.75%, wich is 15%-20% higher than the others'. The activity sequence of W, Co, Bi, Ni oxides on TiO2 support was changed to W>Co>Bi>Ni by the addition of Vanadium.