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The poisoning effects of phosphorus on CeO2-MoO3/TiO2 DeNOx catalysts: NH3-SCR activity and the formation of N2O
Molecular Catalysis ( IF 4.6 ) Pub Date : 2017-06-21 , DOI: 10.1016/j.mcat.2017.06.013
Yanchen You , Huazhen Chang , Tong Zhu , Tao Zhang , Xiang Li , Junhua Li

In this paper, the poisoning effects of phosphorus on CeO2-MoO3/TiO2 catalysts were investigated for their role in selective catalytic reduction of NOx by NH3 (NH3-SCR) applications. A series of P-poisoned CeO2-MoO3/TiO2 catalysts were prepared by the impregnation method. To investigate the deactivation mechanism of NH3-SCR, the samples were characterized by BET, NH3-TPD, XPS, in situ DRIFTS studies and NH3 catalytic oxidation. The activity tests showed that the DeNOx activity declined significantly after phosphorus loading, and a large quantity of N2O formed over the poisoned catalysts. It was found that the active metal sites at the surface were covered by phosphate (mainly cerous phosphate). The chemical deactivation effects of phosphorus on CeO2-MoO3/TiO2 mainly resulted from decreases in the number of active sites and in the adsorption capacity for NOx species. As the loading of phosphorus reached 1.32%, physical deactivation effects, e.g., severe changes in thermal stability and surface structure, also accounted for the decline in activity. The formation of substantial amounts of N2O after phosphorus loading, despite heavily poisoned Ce-sites, might be attributed to Mo-sites being mildly poisoned across the CeO2-MoO3/TiO2 catalyst. Thus, after phosphorus loading, the NH3-SCR occurred mainly on Mo-sites. Lastly, the increase in N2 selectivity at high temperatures with the increasing phosphorus loadings was clarified by a kinetics study.



中文翻译:

磷上的CeO中毒效果2 -MoO 3 /二氧化钛2种DENO X催化剂:NH 3 -SCR活性和形成N 2 ö

在本文中,对CEO磷的中毒效果2 -MoO 3 /二氧化钛2催化剂进行了研究它们在选择性催化还原NO的作用X由NH 3(NH 3 -SCR)应用。采用浸渍法制备了一系列P中毒的CeO 2 -MoO 3 / TiO 2催化剂。为了研究NH 3 -SCR的失活机理,通过BET,NH 3 -TPD,XPS,原位DRIFTS研究和NH 3催化氧化对样品进行了表征。活性测试表明,DeNO x活性磷负荷,和N的大量后显著下降2形成在中毒催化剂O操作。发现表面上的活性金属位点被磷酸盐(主要是磷酸铈)覆盖。磷对CeO 2 -MoO 3 / TiO 2的化学失活作用主要是由于活性位点数量的减少和对NO x物种的吸附能力的降低。当磷的含量达到1.32%时,物理失活作用,例如热稳定性和表面结构的严重变化,也导致了活性的下降。大量N 2的形成尽管Ce位置严重中毒,但磷负载后的O可能归因于Mo位置在整个CeO 2 -MoO 3 / TiO 2催化剂中被轻度中毒。因此,在磷负载后,NH 3 -SCR主要发生在Mo-位点。最后,动力学研究表明,随着磷含量的增加,高温下N 2选择性的增加。

更新日期:2017-06-21
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