Research On The Denitration Performance Of Mn-Ce-V-WO_x/TiO₂ Catalyst And The Catalyst Module Shaping

As the main atmospheric pollutant,NOx was consisted of NO and N₂O etc.which is forming photochemical smog,destroying ozonosphere and doing harm to human health.Nowadays,the selective catalytic reduction?SCR?is the most widely adopted process for flue gas cleaning.In the SCR system,the core is the catalyst which should be sustained lots of dust smog and SO₂.So the key issue of the SCR catalyst industrial application is how to improve the SO₂ resistance and to develop the unit catalyst preparation technology.In this paper,we study the low temperature denitration activity and the SO₂ and H₂O resistance of Mn-Ce--V-WO_x/Ti O₂,and do research the unit catalyst preparation technology.By using the KM493G-1 type diesel engine exhaust SCR denitration catalyst test bed,we study the denitration performance of the honeycomb catalyst in a real flue gas situation and the diesel engine running under different conditions.In this paper,we study the different series low temperature deNOx compound catalyst of Mn-Ce-V-WO_x/TiO₂,Mn-Ce-Fe-V-WO_x/TiO₂ by using the impregnation method mixed Mn?Fe?Ce oxides as additives into V₂O₅-WO₃/TiO₂-based catalyst,introducing simply the regeneration technology of the toxic catalysts and studying the denitration activity and the SO₂ and H₂O resistance of the Mn-Ce-V-WO_x/TiO₂ catalyst.By investigating the denitration active of different catalyst calcination temperature,the proper calcination temperature is 500^oC.In the sulfur resistance test,while the SO₂ concentration>0.09%vol,the catalyst will permanently inactivated.And in the water resistance test,while H₂O concentration is low,catalyst activity will be effected momentarily and recovered again when stop inputting.After SO₂ treatment,the specific surface area of the catalyst after SO₂ treatment was a little decreased,and the intensity and area of catalyst's reduction peaks decreases according to the H₂-TPR results,but the peak area value is still large.According to the SEM results,precipitation forms on the surface of catalyst,but the catalyst keeps reduction activity.In80-hour lifespan test,catalyst activity maintains 90%.According to the Mn-Ce-Fe-V-WO_x/TiO₂ catalyst denitration test,it is indicated that the catalyst has the best performance when the content of Fe is 0.1mol.According to the BET result,the specific surface of Mn-Ce-Fe?0.1?-V-WO_x/TiO₂ in the Mn-Ce-Fe-V-W/TiO₂ series is the largest so that the active component was uniformly dispersed for providing more space to react.In the calcination temperature test,it is indicated that the calcination temperature is the important factor of effecting the catalyst denitration activity and 400 ^oC is the proper one.In this paper,we also studies the effect of O₂ concentration,temperature and airspeed and different molar ratios of[NH₃]/[NO]etc.factors on catalyst's denitration activity.The catalyst has the best performance on the condition of the 3%O₂,the 200 ^oC calcination temperature,the 30000 h^-1 airspeed and NH₃:N₂=1.1.In this paper,we study of the formation technology of cellular SCR catalyst.By adjusting water-powder ratio,adding different kinds of auxiliaries and controlling auxiliaries content,cellular unit catalyst could be produced.By studying the molding process of the honeycomb SCR catalyst,we produce a honeycomb cell by adjusting the ratio of water and material,the kind of additives and the relative amounts of additives.The catalyst blanks has the good formability,and the catalyst has the optimum performance in all aspects when the ratio of water and material is 25%,the amount of additives?E2?is 5%,the amount of additives?F?is 3%,the amount of additives?G?is 4%and the amount of additives?H?is 3%By studying the denitration activity of the honeycomb catalyst in diesel engines running,it indicated that the deNO activity rate is relatively low in low operation mode.when operating stablely the deNO activity rate increased.When the operation mode was running 50%,the deNO removal rate has the max value reaching more than 91.5%.In the mutated operating conditions,most of the temperature range of the deNO activity rate remained at 80%.In the operating conditions,the maximum amount of the NH₃ escaping is 6.0×10^-6 far less than 25×10^-6.