Study On SO₄^2--MnCoCeFe/Ti/Si Low Temperature Denitration Catalyst Based On Application

NO_x is one of the main pollutants of air pollution,which can cause acid rain and photochemical smog,which will cause serious harm to human living environment and health.Selective Catalytic Reduction?SCR?is the most widely used method for treating fixed source nitrogen oxides today.Based on the SO₄^2--Mn-Co-Ce-Fe/TiO₂-SiO₂ catalyst studied previously in the laboratory,this paper looks for a method to reduce the cost without reducing the activity,and on this basis,expands the experimental research.The alkali metal poisoning and active regeneration of the enlarged catalyst were investigated.The molding parameters of the catalyst molding after expansion and the stability of the cyclic reaction under sulfur water conditions were investigated.TiCl₄ was used as raw material,waste acid was used as solvent,40-80 mesh SiO₂ was added to prepare TiO₂-SiO₂ composite carrier,and the loading and preparation conditions between the supports were investigated.And the analysis of the carrier and catalyst by means of XRD,BET,SEM,FTIR and other characterization methods.The results show that the supported catalyst has the highest catalytic activity when the mass ratio of TiCl₄/SiO₂ in the composite carrier is 25 wt%,and the catalytic efficiency reaches 90%at 155°C.Under laboratory conditions,the optimum preparation conditions for the composite support are open-temperature agitation,and the amount of spent acid has little effect on the effect of the final catalyst.The infrared spectroscopy of the catalyst showed that the catalyst had high selectivity to nitrogen.As the temperature increased,the catalytic activity of water poisoning gradually weakened.At about200°C,the peak of the metal sulfate gradually weakens due to the instability of the metal salt sulfate on the surface of the multimetal oxide.Therefore,the catalyst has good sulfur and water resistance.Based on the screening of the carrier,the catalyst was expanded.100 g of the carrier which was enlarged 25 times and 50 times and 200 g of the supported catalyst were prepared.The denitration rate of 100 g of the supported catalyst reached 90%at 173°C,and the activity of the 200 g of supported catalyst reached90%at 225°C.After re-calcination at 300°C,the catalytic activity reached 90%at 176°C,and the activity at low temperature was 15%higher than that before calcination.XRD,BET,SEM,NH₃-TPD analysis showed that oxygen deficiency in the calcination of a large number of catalysts could not be achieved.The catalyst indicates the formation of a catalytically active metal oxide,and the corresponding adsorption capacity for NH₃ is also reduced.The amplified 100 g of the supported catalyst was poisoned.The poisoning effect of alkali metal K on the catalyst is greater than Na.When K/Mn=0.01 mol,the catalyst efficiency of the catalyst at 90?was 90%after K poisoning.When the alkali metal is different in content,the degree of poisoning of the catalyst is proportional to the alkali metal content.The poisoned catalyst is regenerated by pickling and water washing.The pickling method is better than the water washing regeneration.After the water washing,the catalytic activity is 10%higher than that of the poisoning catalyst,and the activity after acid washing is increased by 34%,which basically reaches the activity of fresh catalyst.The enlarged catalyst was subjected to a molding process,and the relevant molding parameters were examined.The results show that the catalyst activity is best at 5%O₂,10%H₂O,ammonia to nitrogen ratio of 1,and SO₂ concentration of 50 ppm,reaching 90%at 173?.At the same time,the activity of the catalyst decreases as the initial concentration of NO increases,and decreases as the space velocity increases.The catalyst reached 90%at 183?under a space velocity of30 000 h^-1.Cost analysis shows thatmaterial cost of the catalyst is about 36 000yuan/ton.