Study On Preparation And Application Of Low Temperature SCR Denitration Catalyst

China is the country with abundent coal resources.And coal consumption accounted for more than 60% of the primary energy consumption.In the consumption of coal,more than 80% are used to direct combustion.Sulfur oxides?SO_x?,nitrogen oxides?NO_x?,dust and other pollutants produced in the process of coal combustion have caused serious harm to the ecological environment and human health.Flue gas desulfurization and dust removal technology has been widely developed,and high temperature flue gas denitration technology has also been widely developed.But low temperature flue gas denitration technology is is still immature,so it has become an important issue in the field of environmental protection.In this paper,the preparation and properties of low temperature selective catalytic reduction?SCR?catalyst were studied by using modified activated carbon as the carrier and the transition metal as the active component.The activated carbon modified by oxidation with concentrated nitric acid,and Mn,Fe,Co,Ce as the active component is added to the modified activated carbon carrier by impregnation method,then under the protection of inert gas,the activated carbon was calcined at high temperature and cooled to obtain catalyst.The catalyst was tested based on fixed bed,using NH3 as the reducing agents,and the mixture of air,NO,SO₂,N₂ and other gases to simulate the flue gas.The effects of temperature,space velocity,SO₂ concentration and impregnation component on the catalytic activity of the catalyst were studied.The experimental results show that the catalyst prepared in this paper has high catalytic activity for NO at low temperature,and the denitrification efficiency is up to 99%.The catalyst has a certain resistance to sulfur,low concentration of SO₂ in a short period of time has little effect on the activity of the catalyst,but the presence of SO₂ for a long time will lead to the occurrence of side effects of ammonium sulfate catalyst deactivation.And the catalyst has no obvious deactivation in 80 h and has a long service life.On the basis of laboratory test,the pilot test of low temperature SCR denitration catalyst was carried out cooperating with Jinan Iron and Steel Group Company Limited and Qingdao Benzo Chemical Company Limited.And SO_x,dust,CO,and other components exist.Therefore,the line experiment of the catalyst was used in the pilot process.In order to promote the industrial application of the catalyst,a series of experiments were carried out to optimize the preparation process.The preparation process of the catalyst was amplified,and the deactivated catalyst was analyzed and regenerated.The experimental results show that in the temperature of 120?,the space velocity of 3750h^-1,the denitrification rate of catalyst prepared by 10% nitric acid can be kept above 90% in two hours.The effect of NaOH solution soaking on catalyst activity was not significant.The denitrification rate of 2.5%Mn-2.5%Fe/AC was up to 84% and the impregnation ratio of Mn and Fe was the highest,so 2.5%Mn-2.5%Fe was used as the active component of the catalyst.In subsequent preparation,dilute nitric acid instead of concentrated nitric acid was used in oxidation modification of activated carbon.And the process of NaOH solution soaking was omitted.The catalyst was successfully prepared by pilot process,and the preparation amount was up to 1kg.Jinan International line experiment has been successful debugging,the corresponding initial denitrification rate reached 99%,and the running time is up to forty hours.Qingdao Sanli bennuo biomass denitration project is still in the debugging stage,the denitrification rate is about 50%.The denitrification rate remained stable after ten days.