Promotion Effect of Nb-modification of MnTiOx Catalysts in Low-temperature NH3-SCR Reactivity and K-resistant
The flue gas from sintering process in the steel industry contains a large amount of nitrogen oxides(NOx),which seriously damages the environment and threatens human health.The most effective DeNOx method is selective catalytic reduction by NH3(NH3-SCR).Among the numbers of NH3-SCR catalysts,MnTiOx catalyst exhibits excellent low-temperature activity and has good prospects for DeNOx of sintering flue gas.However,in actual application,MnTiOx is very sensitive to alkali metal(e.g.K)poisoning.Therefore,in this paper,MnTiOx was modified by Nb to improve the resistance of alkali metal K poisoning.This paper investigated the effect of different Nb content on the NH3-SCR reaction performance and K-resistance of MnTiOx.The Nb-modified MnTiOx catalysts showed significantly higher low-temperature NH3-SCR performance and alkali metal K-resistance than the original catalyst.The results suggested that when the Nb/Ti mole ratio was less than 0.04,K-poisoning formed obvious K-Mn oxide species on the catalyst,reducing the number and strength of acidic sites,and decreasing the proportion of Mn4+and active oxygen species,which might be responsible for the decreased reaction activity after K poisoning.Nb-modification increases the number and proportion of acidic sites,Mn4+,and active oxygen species on the catalyst,and the decrease of these species after K poisoning is significantly reduced,which leads to the improvement of the reaction activity and resistance to alkali metal K poisoning of the MnTiOx catalysts after Nb-modification.
NH3-SCRlow-temperature reactivityK-resistanceMnTiOx metal oxideNb-modification
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