Nb对MnTiO_(x)在烧结烟气的NH_(3)-SCR低温催化活性及抗钾毒化的促进作用  

Promotion Effect of Nb-modification of MnTiO_(x)Catalysts in Low-temperature NH_(3)-SCR Reactivity and K-resistant

作　　者：喻瑞 朱繁[1] 史光[1] 崔俊明 张维萍[2] YU Rui;ZHU Fan;SHI Guang;CUI Jun-ming;ZHANG Wei-ping(MCC Capital Engineering&Research Incorporation Ltd.,Beijing 100176,China;State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]中冶京诚工程技术有限公司,北京100176 [2]大连理工大学精细化工国家重点实验室化工学院,辽宁大连116024

出　　处：《分子催化（中英文）》2024年第5期427-436,I0002,共11页Journal of Molecular Catalysis(China)

摘　　要：钢铁行业的烧结烟气中存在大量的氮氧化物(NO_(x)),严重破坏环境,并威胁人类健康.目前NO_(x)脱除(DeNO_(x))最有效的方法是氨气选择性催化还原法(NH_(3)-SCR).在众多NH_(3)-SCR催化剂中,MnTiO_(x)催化剂表现出较好的低温活性,具有较好的烧结烟气脱硝应用前景.但实际应用中,MnTiO_(x)容易受到以K为代表的碱金属物种的毒化.因此,采用Nb针对性地对MnTiO_(x)进行改性,以提高催化剂的抗碱金属中毒性能.我们考察了引入不同Nb含量对MnTiO_(x)NH_(3)-SCR反应性能和抗碱金属性能的影响.Nb改性后的MnTiO_(x)催化剂相较于原催化剂,其反应性能和抗碱金属K中毒的性能均具有显著提高.结果表明,当Nb含量较低时,K会在催化剂上形成较为明显的钾锰氧化物物种,减少催化剂上酸性位点的数量和强度,并降低Mn4+和活性氧物种的比例,这是催化剂K中毒后反应活性降低的原因.引入Nb后,增加了催化剂的酸性位点、Mn4+和活性氧物种的比例,并且K中毒之后,这些物种下降的幅度明显减少,因此引入Nb后使得催化剂的反应活性和抗碱金属中毒性能大幅提升.The flue gas from sintering process in the steel industry contains a large amount of nitrogen oxides(NO_(x)),which seriously damages the environment and threatens human health.The most effective DeNO_(x)method is selective catalytic reduction by NH_(3)(NH_(3)-SCR).Among the numbers of NH_(3)-SCR catalysts,MnTiO_(x)catalyst exhibits excellent low-temperature activity and has good prospects for DeNO_(x)of sintering flue gas.However,in actual application,MnTiO_(x)is very sensitive to alkali metal(e.g.K)poisoning.Therefore,in this paper,MnTiO_(x)was modified by Nb to improve the resistance of alkali metal K poisoning.This paper investigated the effect of different Nb content on the NH_(3)-SCR reaction performance and K-resistance of MnTiO_(x).The Nb-modified MnTiO_(x)catalysts showed significantly higher low-temperature NH_(3)-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 MnTiO_(x)catalysts after Nb-modification.

关 键 词：NH_(3)-SCR 低温活性 抗钾中毒 MnTiO_(x)氧化物 Nb改性 

分 类 号：O643.32[理学—物理化学]