摘要
目的构建具有优异低温活性的CO-SCR催化体系,探索Cu引入对Pd基催化剂电子结构与催化性能的影响机制。通过调控Cu与Pd之间的协同作用,优化催化剂对CO和NO的吸附行为,从而提升NOx转化效率及N2选择性等,为高效低温脱硝催化剂的设计提供理论依据与实践指导。方法通过微弧氧化、碱热处理、水热反应、离子交换和共沉淀等方法,成功制备了一种基于钛网支撑的CuPd-TiO_(2)/Ti整体式催化剂,并用于低温CO选择性催化还原NO_(x)。结果测试结果表明,该催化剂展示出了卓越的低温催化性能,主要得益于其较高的比表面积、优良的分散性以及Cu-Pd合金的催化活性。与单一Pd催化剂相比,CuPd-TiO_(2)/Ti催化剂表现出更强的NO吸附能力和更高的N2选择性。在120℃时,该催化剂实现了100%的NO_(x)转化率,并在200℃时达到100%的N_(2)选择性。此外,该催化剂在长期反应中表现出优异的稳定性和抗硫能力。结论基于XPS、H_(2)-TPR和原位DRIFTS等表征技术,探讨了Cu-Pd合金的形成机制及其在反应过程中的催化机理。研究发现,Cu的引入通过电子转移促进Pd0物种的形成,提高其在TiO_(2)表面的分散性,并优化CO与NO的吸附行为,从而协同提升了催化剂的氧化还原能力和整体催化性能。
The work aims to report the successful design and synthesis of a novel monolithic Cu1Pd1-TiO_(2)/Ti catalyst supported on a titanium mesh,tailored for the selective catalytic reduction of NO_(x)with CO(CO-SCR)under low-temperature and oxygen-rich conditions.This catalyst was fabricated through a series of well-controlled and integrated processes including plasma electrolytic oxidation(PEO),alkali hydrothermal treatment,hydrothermal growth,ion exchange,and co-precipitation.This elaborated approach facilitated the in situ growth and immobilization of Cu-Pd bimetallic species on a durable TiO_(2)-coated Ti support,resulting in a catalyst with excellent mechanical stability and high dispersion of active species.Compared to conventional Pd-TiO_(2)/Ti systems,the Cu1Pd1-TiO_(2)/Ti catalyst exhibited significantly enhanced catalytic properties and structure.BET analysis revealed a substantial increase in specific surface area,attributed to the optimized nanostructured morphology of the TiO_(2)layer and the homogeneous distribution of Cu and Pd species.High-resolution transmission electron microscopy(HR-TEM)and selected area electron diffraction(SAED)confirmed the successful formation of a well-alloyed Cu-Pd phase,with particle sizes uniformly distributed in the nanometer range.The alloying effect led to a remarkable improvement in the adsorption capacity of both NO and CO,as verified by in situ FT-IR spectroscopy.Specifically,Cu sites promoted the activation and dissociation of NO molecules,while Pd sites enhanced CO oxidation activity,together creating a synergistic effect that greatly accelerated the NO reduction pathway.Additionally,X-ray photoelectron spectroscopy(XPS)confirmed the dominant presence of metallic Cu^(0)and Pd^(0),which served as key active sites.H2-TPR results indicated enhanced reducibility due to strong metal-support interaction and Cu-Pd alloying.In situ FT-IR analysis further revealed that the Cu-Pd alloy improved NO desorption at low temperatures.Cu^(+)species,formed transiently during the reaction,facilitated NO adsorption and activation,while also acting as electron mediators between NO and CO.Under mild thermal conditions,Cu^(+)interacted with NO and was subsequently reduced to Cu^(0)by CO,establishing a Cu^(+)/Cu^(0)redox cycle that continuously regenerated active sites.This dynamic cycle significantly accelerated NO reduction and accounted for the exceptional low-temperature CO-SCR activity of the catalyst.Under reaction conditions containing 0.07%O_(2),the Cu1Pd1-TiO_(2)/Ti catalyst achieved 100%NO conversion at a remarkably low temperature of 120℃,and exhibited 100%N_(2)selectivity at 200℃.These performance metrics surpassed those of previously reported Pd-based catalysts under comparable conditions.Furthermore,the catalyst demonstrated robust sulfur tolerance,maintaining high NO conversion and N_(2)selectivity even after exposure to SO_(2)-containing feed gases,highlighting its promising durability for practical application.The in situ fabrication strategy also ensured strong adhesion between the active layer and the Ti support,contributing to the structural stability of the catalyst during long-term operation.This monolithic configuration minimized the risk of catalyst loss or delamination,a common issue in powder-based systems.The combination of low-temperature activity,high N_(2)selectivity,sulfur resistance,and mechanical robustness highlighted the practical applicability of Cu1Pd1-TiO_(2)/Ti catalysts in NO_(x)abatement from stationary and mobile emission sources.Overall,this work presents a significant advancement in the design of CO-SCR systems by integrating bimetallic alloy engineering and structured catalyst fabrication.The insights gained into the reaction mechanism and the synergistic behavior of Cu and Pd provide a solid foundation for the rational development of next-generation environmental catalysts.
作者
刘婷婷
杨柳
刘付浩
李馨宇
何函泽
李晶
刘宝丹
LIU Tingting;YANG Liu;LIU Fuhao;LI Xinyu;HE Hanze;LI Jing;LIU Baodan(Foshan Graduate School of Innovation,Northeastern University,Guangdong Foshan 528312,China;School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)
出处
《表面技术》
北大核心
2025年第15期134-144,155,共12页
Surface Technology
基金
中央高校基本科研业务费项目(N2229002)
东北大学佛山研究生生创新学院科研启动项目(FSNEU20201016001,FSNEU20201016003)
佛山市高层次人才科研启动项目(200076622001,200076622004)。
