The Mechanism Of The Effect Of Alkali/alkaline Earth Metal And Halogen Deposition On The Performance Of Mn-Ce/TiO 2 Low Temperature SCR Denitration Catalyst

Nitride oxides?NO_x?is one of the important pollutants in the atmosphere.NH3-SCR is considered to be the most efficient and widely used technology for reduction NO_x emission from stationary sources.Recently,there has been strong interest in developing a superior SCR catalyst with high activity at low temperature range.Although the low temperature SCR catalysts could avoid the corrosion in the presence of SO₂,even in the low concentration range after the desulfurization devices.SO₂ could react with NH3 to form the sulfate species,which did not decompose at low temperature and finally deposited on the catalyst surface.However,there is still a small amount of dust which contains many physical and chemical poisoning species such as alkali/alkaline earth metals in flue gas.Therefore,it is valuable to investigate the interaction of deposited alkali metal and SO₂ on the physical and chemical properties of Mn-Ce/TiO₂ catalysts.In this study,Mn-Ce supported on TiO₂ as the vector,the Mn-Ce/TiO₂ catalysts doped by Alkali/alkaline earth metal,halogen and synergied by Alkali/alkaline earth metal with halogen was systematically investigated.First of all,prepare the alkali/alkaline earth metals deposited Mn-Ce/TiO₂ catalysts through an impregnation method.The influence of alkali/alkaline earth metals on the performance of the Mn-Ce/TiO₂ catalyst for low-temperature selective catalytic reduction of NO by NH3 was investigated.Experimental results showed that the alkali/alkaline earth metals had negative effects on the activity of Mn-Ce/TiO₂ catalysts;different precursors of alkali/alkaline earth metals also had negative effect the catalytic activity with different degree and increase of amount of influence of alkali/alkaline earth metals could aggravate the negative.The samples were characterized by different instruments,the characterization results indicated that the alkali/alkaline earth metals doped could alter the catalyst surface physical properties and generate corresponding chemical changes,which could be considered as the main reasons for the deactivation.Secondly,chlorine?CI??iodine?I??olfactory?Br?were chosen as the halogen deposited Mn-Ce/TiO₂,Experimental results showed that the alkali/alkaline earth metals had negative effects on the activity of Mn-Ce/TiO₂,when the amount of halogen was less than 0.1%,the effect of halogen was remission.Furthermore,the influence on synergied by Alkali/alkaline earth metal with halogen was investigated.It was found that the synergied by Alkali/alkaline earth metal with halogen also had negative effect the catalytic activity.With the analysis different of halogen,we have found this regular:Ca>Mg>Na>K?Through the systematic study,Clearing the mechanism of Alkali/alkaline earth metal and halogen doped on Mn-Ce/TiO₂ catalysts,and the influence of synergied by Alkali/alkaline earth metal with halogen was investigated,these studies can provide the theory basis for some catalysts in low flue gas temperature or complex flue gas contents in industrial boilers and furnaces,it also could provide technical support for NO_x control in our country has the important significance of environmental,economic and social.