An investigation on the promoting effect of Pr modification on SO2 resistance over MnOx catalysts for selective reduction of NO with NH3
An investigation on the promoting effect of Pr modification on SO2 resistance over MnOx catalysts for selective reduction of NO with NH3
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Pr改性对MnOx催化剂NH3选择性还原NO的抗SO2促进作用研究
DOI：
10.1007/s11356-021-17006-3
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发表时间：
2021-07
影响因子：
5.8
通讯作者：
潘新祥
中科院分区：
文献类型：
--
作者：
翟广鹏;韩志涛;杜还;高宇;潘新祥
通过共沉淀法合成了pr改性MnOx催化剂，结果表明，MnPrOx催化剂比原始MnOx催化剂具有更好的选择性催化还原（SCR）活性和抗SO2性能。在MnOx催化剂中加入Pr后，在120 ~ 220℃的温度下，NO的转化效率完全提高。此外，与MnOx催化剂相比，pr改性的MnOx催化剂表现出更强的抗H2O和SO2性能。在SO2和H2O作用4 h后，MnPrOx催化剂的NO转化率可保持在87.6%。采用XRD、BET、氢温程序还原（H2-TPR）、氨温程序脱附（NH3-TPD）、XPS、TG和原位漫反射红外光谱（DRIFTS）等表征技术，进一步探讨Pr掺杂MnOx催化剂对抗SO2性能的促进作用。结果表明，与MnOx催化剂相比，MnPrOx催化剂具有更大的比表面积、更强的还原性和更多的L酸位。MnPrOx-S催化剂表面Mn4+/Mnn+的相对比例也远高于MnOx催化剂。重要的是，当原料气中存在SO2时，MnPrOx催化剂中的PrOx物质会优先与SO2反应，从而保护Mn活性位点。此外，Pr的引入可能会促进SO2与NH3的反应，而不是SO2与Mn活性位点的反应，这也有助于在很大程度上保护Mn活性位点。由于原料气中SO2的存在对MnPrOx催化剂表面NH3吸附的影响较小，且SO2对NO吸附的抑制作用有所缓解，因此在pr修饰的MnOx催化剂上，通过Eley-Rideal （E-R）机理进行的SCR反应仍能接近正常进行，而通过Langmuir-Hinshelwood （L-H）机理进行的SCR反应受到轻微抑制。
Pr-modified MnOx catalyst was synthesized through a facile co-precipitation process, and the results showed that MnPrOx catalyst exhibited much better selective catalytic reduction (SCR) activity and SO2 resistance performance than pristine MnOx catalyst. The addition of Pr in MnOx catalyst led to a complete NO conversion efficiency in 120–220 °C. Moreover, Pr-modified MnOx catalyst exhibited a superior resistance to H2O and SO2 compared with MnOx catalyst. After exposing to SO2 and H2O for 4 h, the NO conversion efficiency of MnPrOx catalyst could remain to 87.6%. The characterization techniques of XRD, BET, hydrogen-temperature programmed reduction (H2-TPR), ammonia-temperature programmed desorption (NH3-TPD), XPS, TG and in situ diffuse reflectance infrared spectroscopy (DRIFTS) were adopted to further explore the promoting effect of Pr doping in MnOx catalyst on SO2 resistance performance. The results showed that MnPrOx catalyst had larger specific surface area, stronger reducibility, and more L acid sites compared with MnOx catalyst. The relative percentage of Mn4+/Mnn+ on the MnPrOx-S catalyst surface was also much higher than those of MnOx catalyst. Importantly, when SO2 exists in feed gas, PrOx species in MnPrOx catalyst would preferentially react with SO2, thus protecting the Mn active sites. In addition, the introduction of Pr might promote the reaction between SO2 and NH3 rather than between SO2 and Mn active sites, which was also conductive to protect the Mn active sites to a great extent. Since the presence of SO2 in feed gas had little effect on NH3 adsorption on the MnPrOx catalyst surface, and the inhibiting effect of SO2 on NO adsorption was alleviated, SCR reactions could still proceed in a near-normal way through the Eley-Rideal (E-R) mechanism on Pr-modified MnOx catalyst, while SCR reactions through the Langmuir-Hinshelwood (L-H) mechanism were suppressed slightly.
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影响因子：
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作者：
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影响因子：
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