季科, 钟金钦, 刘冰冰, 郭健翔. 掺Nb改性促进Mn-Cu/BCN催化剂低温SCR脱硝性能的机制研究[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0019
引用本文: 季科, 钟金钦, 刘冰冰, 郭健翔. 掺Nb改性促进Mn-Cu/BCN催化剂低温SCR脱硝性能的机制研究[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0019
JI Ke, ZHONG Jinqin, LIU Bingbing, GUO Jianxiang. Mechanism study on the enhancement of low-temperature SCR denitrification performance of Mn-Cu/BCN catalyst by Nb doping modification[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0019
Citation: JI Ke, ZHONG Jinqin, LIU Bingbing, GUO Jianxiang. Mechanism study on the enhancement of low-temperature SCR denitrification performance of Mn-Cu/BCN catalyst by Nb doping modification[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0019

掺Nb改性促进Mn-Cu/BCN催化剂低温SCR脱硝性能的机制研究

Mechanism study on the enhancement of low-temperature SCR denitrification performance of Mn-Cu/BCN catalyst by Nb doping modification

  • 摘要: 氨法选择性催化还原(NH3-SCR)脱硝技术是目前应用最为广泛的脱除NOx技术,技术核心是开发出具有廉价、高效、抗中毒性能强的催化剂。本研究针对现有商用催化剂处理低温烟气脱硝性能差、反应温窗窄、抗中毒性能差等问题,利用微波辅助浸渍法通过掺Nb改性制备了具有良好低温催化活性的Mn7-Cu3-Nbx/BCN催化剂。NH3-SCR测试结果表明,掺Nb量为0.05%的Mn7-Cu3-Nb0.05/BCN催化剂表现出了最佳的SCR催化活性,该催化剂在150−275 ℃温区范围内具有不低于94%的NO转化率,且N2选择性也得到提升。抗水抗硫中毒实验结果表明,掺Nb改性催化剂Mn7-Cu3-Nb0.05/BCN同样具有较好的抗中毒性能,在通入100 ppm SO2和5% H2O 14.75 h后,其NO转化率仍能稳定维持在75%以上。结合SEM、XRD、XPS、NH3-TPD、NO-TPD以及原位红外漫反射(in-situ DRIFT)等多种表征手段详细探究了掺Nb改性对于Mn7-Cu3/BCN催化剂低温SCR脱硝性能的增强机制。结果表明,掺Nb改性能够有效抑制Mn7-Cu3/BCN催化剂表面上CuO和Cu物种的结晶,进一步促进了活性组分的均匀分散。同时,Nb的掺杂有效提升了Mn4+和Oα物种浓度,促使更多的NO被氧化为NO2,促进了“Fast-SCR”反应进程。此外,掺Nb改性能够促进NH3和NO的吸附与活化,促使更多的-NH2、硝酸盐等有益中间体加速形成,进而有效提升了SCR脱硝反应的整体反应速率。本研究为深入理解掺Nb改性的影响机制提供了重要的科学依据,并为低温烟气脱硝技术的发展提供了有益的探索和参考。

     

    Abstract: With the rapid process of industrialization, the emission of nitrogen oxides (NOx) has become increasingly prominent and has become a key issue that urgently needs to be addressed in the field of environmental protection. The excessive emission of NOx not only causes acid rain, exacerbates urban haze and other environmental problems, but also poses an undeniable threat to human health. Therefore, it is particularly important to develop and apply efficient NOx reduction technologies, which have significant implications for improving air quality and protecting the ecological environment. Among numerous technologies, ammonia selective catalytic reduction (NH3-SCR) technology is highly favored due to its excellent performance and practicality, and has become the most widely used NOx removal technology at present. The core of this technology lies in the development of catalysts that are both cost-effective, highly effective, and possess strong anti poisoning properties. This study aims to address the problems of poor denitrification performance, narrow reaction temperature window, and poor anti poisoning performance of existing commercial catalysts for low-temperature flue gas treatment. A Mn7-Cu3-Nbx/BCN catalyst with good low-temperature catalytic activity was prepared by microwave-assisted impregnation method through Nb doping modification. The NH3-SCR test results showed that the Mn7-Cu3-Nb0.05/BCN catalyst with a Nb content of 0.05% exhibited the best SCR catalytic activity. The catalyst had a NO conversion rate of not less than 94% in the temperature range of 150−275 ℃, and the N2 selectivity was also improved. The experimental results of anti water and anti sulfur poisoning showed that the Nb doped modified catalyst Mn7-Cu3-Nb0.05/BCN also had good anti poisoning performance. After introducing 100 ppm SO2 and 5% H2O for 14.75 hours, its NO conversion rate can still be stably maintained at over 75%. The enhancement mechanism of Nb doped modification on the low-temperature SCR denitrification performance of Mn7-Cu3/BCN catalyst was investigated in detail using various characterization methods such as SEM, XRD, XPS, NH3-TPD, NO-TPD, and in-situ infrared diffuse reflectance spectroscopy (in-situ DRIFT). The results indicated that Nb doping modification can effectively suppress the crystallization of CuO and Cu species on the surface of Mn7-Cu3/BCN catalyst, further promoting the uniform dispersion of active components. Meanwhile, the doping of Nb effectively increased the concentration of Mn4+and Oα species, promoting the oxidation of more NO to NO2 and facilitating the “Fast-SCR” reaction process. In addition, In addition, Nb doping modification could enhance the surface acidity of the catalyst, promote the adsorption and activation of NH3 and NO, accelerate the formation of more beneficial intermediates such as -NH2 and nitrate, and effectively improve the overall reaction rate of SCR denitrification reaction. In addition, Nb doping modification could effectively reduce the poisoning effect of SO2, and this excellent anti sulfur poisoning performance was mainly attributed to the effective suppression of sulfate formation on the catalyst surface by the introduction of Nb, especially the metal sulfate MnSO4. This study provides important scientific basis for a deeper understanding of the impact mechanism of Nb doping modification, and provides useful exploration and reference for the development of low-temperature flue gas denitrification technology.

     

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