Research Of Preparation And Denitration Property Of Monolithic Manganese Base Catalyst

Selective catalytic reduction(SCR)of NOx removal is a highly effective denitration technology,while due to the temperature limitation of its core part,catalyst,which results in not universally applying in all flue gas environment.Thus,with regard to the low flue gas temperature of industrial kilns that are confronted with urgent denitration task,the denitration catalyst at low temperature has to be developed.This paper was based on manganese active component,the monolithic manganese base catalyst of low temperature was prepared in step-wise mix method,the effect of some factors on performance of catalyst was explored including proportion of active components,supports and preparation process of catalyst.Through a series of characterization of BET,XRD,NH3-TPD,H2-TPD etc.,the macroscopic reasons affecting performance of catalyst was further analyzed,the main results were summarized as follows:In manganese base catalysts prepared by step-wise mix method,the activity of which at low temperature can be improved by doping Ce,and raised more by doping of combined manganese salts,which makes denitration rate of catalyst at 80? be enhanced by 50%,the characterization of catalysts shows that specific surface area,surface acid amount and redox properties of catalyst are markedly increased by doping of combined manganese salts.In study of three different support series of catalysts containing MN-Ce/Z,MA-Ce/Z,MN-MACe/Z(Z as Ti O2,Si O2,Al2O3),Ti O2 support displays excellent comprehensive performance,and there is certain adaptability between support and manganese salt active component,the characterization of catalysts presents that catalyst with Ti O2 as support has a denser apparent morphology,larger specific surface area and more surface acid amount.From research of constituent and preparation technique of MN-MA-Ce/Ti O2 catalyst,it is found that catalyst just has excellent activity at low temperature,only when the molar ratio of MN/MA is between 3:1~5:1 and that of Mn/Ce is above 10.The calcined temperature of catalyst below 500? only results in good denitration at low temperature,the calcined time of catalyst hardly influences the properties of catalyst.In powder preparation process of step-wise mix method,the thermal decomposed manganese salt on surface of powder and the volatilization of acetic acid can both decrease the activity of catalyst at low temperature.Comparing the activity of catalysts prepared by step-wise mix and one step mix,it is demonstrated that the denitration rate of catalyst with one step mix is far below that of one with step-wise mix.The extending study of doping of combined manganese salts reveals that manganese nitrate only combines with carboxylic acid manganese salts,just resulting in a heightening activity of manganese base catalyst at low temperature.The NH3-TPD test of catalysts shows that the amount of dium-strong acid augmented greatly is related to activity of catalyst at low temperature.The research of reaction conditions of catalyst indicates that the increase of space velocity can significantly reduce the denitration rate of catalyst,and O2 content and ammonia nitrogen ratio has a relative saturation value.