Sm掺杂改性以TiO2为载体的Fe基催化剂及NH3-SCR脱硝性能研究

　　

摘要：针对现有Fe/TiO₂催化剂在NH₃-SCR反应中表现出的低温活性不足、有效反应温窗较窄等问题，采用水热法制备了一系列不同Sm掺杂量的Fe/TiO₂催化剂，并结合NH₃-SCR活性测试、SEM、BET、XRD、XPS和NH₃-TPD表征，系统研究了Sm掺杂对催化剂结构与表面性质的影响。结果表明，适量Sm掺杂能够明显提高Fe/TiO₂催化剂的低温脱硝活性并拓宽高活性温窗，其中Sm_0.6Fe/TiO₂表现出最佳综合性能。表征结果显示，Sm掺杂未改变TiO₂载体以锐钛矿相为主的晶相结构，Fe和Sm物种主要以高分散状态存在于载体表面或近表层；同时Sm掺杂提高了催化剂的比表面积和总孔容，优化了介孔结构；XPS与NH₃-TPD结果进一步表明，Sm改性有助于增加表面活性氧物种，增强表面酸性及NH₃吸附能力。研究表明，适量Sm掺杂可通过改善Fe/TiO₂催化剂的孔结构参数和表面化学性质，有效提升其低温NH₃-SCR脱硝性能，并明确了较适宜的Sm掺杂比例，为TiO₂负载Fe基催化剂的优化设计提供了实验依据。

关键词：NH₃-SCR；脱硝性能；Sm掺杂；Fe/TiO₂催化剂;

Abstract: Aiming at the shortcomings of conventional Fe/TiO₂ catalysts in the NH₃-SCR reaction, such as insufficient low-temperature activity and a narrow effective operating temperature window, a series of Fe/TiO₂ catalysts with different samarium (Sm) doping contents were synthesized via the hydrothermal method. Combined with NH₃-SCR activity evaluation and a variety of characterizations including SEM, BET, XRD, XPS and NH₃-TPD, the influences of Sm doping on the structure and surface physicochemical properties of the catalysts were systematically studied. The results show that appropriate Sm doping can remarkably promote the low-temperature denitrification activity of Fe/TiO₂ catalysts and expand the high-activity temperature window, among which Sm_0.6Fe/TiO₂ displays the best overall catalytic performance. Characterization results reveal that Sm doping does not change the anatase-dominated crystalline phase of the TiO₂ support, and Fe and Sm species are mainly distributed in a highly dispersed state on the surface or subsurface of the support. Meanwhile, Sm doping increases the specific surface area and total pore volume of the catalyst, and optimizes its mesoporous structure. Further XPS and NH₃-TPD analyses demonstrate that Sm modification is conducive to increasing the content of surface active oxygen species, strengthening surface acidity and improving NH₃ adsorption capacity. This work indicates that moderate Sm doping can effectively enhance the low-temperature NH₃-SCR denitrification performance of Fe/TiO₂ catalysts by regulating their pore structural parameters and surface chemical properties. The suitable Sm doping ratio is identified, which provides an experimental foundation for the rational design and optimization of TiO₂-supported Fe-based catalysts.

Key words: NH₃-SCR; NO_x reduction performance; Sm doping; Fe/TiO₂ catalyst;

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