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-TiO2/Ti整体式催化剂,并用于低温CO选择性催化还原NOx。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-TiO2/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NOx转化率,并在200 ℃时达到100%的N2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、H2-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TiO2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。
Abstract
The work aims to report the successful design and synthesis of a novel monolithic Cu1Pd1-TiO2/Ti catalyst supported on a titanium mesh, tailored for the selective catalytic reduction of NOx 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 TiO2-coated Ti support, resulting in a catalyst with excellent mechanical stability and high dispersion of active species. Compared to conventional Pd-TiO2/Ti systems, the Cu1Pd1-TiO2/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 TiO2 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 Cu0 and Pd0, 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 Cu0 by CO, establishing a Cu+/Cu0 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% O2, the Cu1Pd1-TiO2/Ti catalyst achieved 100% NO conversion at a remarkably low temperature of 120 ℃, and exhibited 100% N2 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 N2 selectivity even after exposure to SO2-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 N2 selectivity, sulfur resistance, and mechanical robustness highlighted the practical applicability of Cu1Pd1-TiO2/Ti catalysts in NOx 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.
关键词
Cu-Pd合金催化剂 /
金属丝网 /
CO-SCR /
低温活性 /
氮氧化物 /
原位生长
Key words
Cu-Pd alloy catalysts /
metal mesh /
CO-SCR /
low-temperature activity /
nitrogen oxides /
in situ growth
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] LIU T K, WEI L Q, YAO Y Y, et al.La Promoted CuO-MnOx Catalysts for Optimizing SCR Performance of NO with CO[J]. Applied Surface Science, 2021, 546: 148971.
[2] WANG X Y, ZHAO L, LI X Y, et al.Unveiling the Promotion Effects of CoO on Low-Temperature NO Reduction with CO over an In-Situ-Established Co3O4-CoO Heterostructure[J]. ACS Sustainable Chemistry & Engineering, 2021, 9(17): 6107-6117.
[3] JIANG R H, LIU S M, LI L, et al.Single Ir Atoms Anchored on Ordered Mesoporous WO3 Are Highly Efficient for the Selective Catalytic Reduction of NO with CO under Oxygen-Rich Conditions[J]. ChemCatChem, 2021, 13(7): 1834-1846.
[4] 杜倩文. 基于Mn系催化剂的CO-SCR脱硝抗硫抗水性能研究[D]. 济南: 山东大学, 2021.
DU Q W.Study on Sulfur Resistance and Water Resistance of CO-SCR Denitration Based on Mn Catalyst[D]. Jinan: Shandong University, 2021.
[5] JIANG L J, LIANG Y, LIU W Z, et al.Synergistic Effect and Mechanism of FeOx and CeOx Co-Doping on the Superior Catalytic Performance and SO2 Tolerance of Mn-Fe-Ce/ACN Catalyst in Low-Temperature NH3-SCR of NOx[J]. Journal of Environmental Chemical Engineering, 2021, 9(6): 106360.
[6] LI S M, HUANG Y, ZHU H, et al.Dual Improvement in Acid and Redox Properties of the FeOx /OAC Catalyst via APS Oxygen-Functionalization: High Low-Temperature NH3-SCR Activity, SO2 and H2O Tolerance[J]. Fuel, 2023, 341: 127716.
[7] CHEN X L, LIU Y Q, LIU Y, et al.Recent Advances of Cu-Based Catalysts for NO Reduction by CO under O2-Containing Conditions[J]. Catalysts, 2022, 12(11): 1402.
[8] MENG Y X, LIU S M, WANG Y X, et al.Hollow Mn-Doped CeO2@Co3O4 Catalyst for NO Reduction by CO[J]. Journal of Catalysis, 2024, 430: 115311.
[9] 鲁冬, 杜亚丽, 刘江宁, 等. 可还原性氧化物负载铜基催化剂CO-SCR性能研究[J]. 功能材料, 2022, 53(11): 11007-11014.
LU D, DU Y L, LIU J N, et al.Research on CO-SCR Performance of Reducible Oxide Supported Copper-Based Catalysts[J]. Journal of Functional Materials, 2022, 53(11): 11007-11014.
[10] SUN R B, YU P F, WAN Y J, et al.Reducing N2O Formation over CO-SCR Systems with CuCe Mixed Metal Oxides[J]. ChemCatChem, 2021, 13(11): 2709-2718.
[11] CHEN K T, HAN X Y, WANG Q, et al.Enhanced CO-SCR Denitration on Supported Rh-Mn/CoAlOx Catalysts through Rh-Mn Interaction[J]. Applied Surface Science, 2024, 665: 160357.
[12] YANG L, LI J, CAO G Q, et al.Flexible Monolithic Pt/CuO-Fe2O3/TiO2 Catalysts Integrated on Ti Mesh for Efficient NO Removal via CO-SCR Reaction[J]. Journal of Environmental Chemical Engineering, 2023, 11(6): 111262.
[13] CHEN L, WU X P, GONG X Q.A Comparative DFT+U Study of CO Oxidation on Pd- and Zr-Doped Ceria[J]. Journal of Rare Earths, 2023, 41(7): 1042-1048.
[14] YANG F, ZHANG Y, LIU P F, et al.Pd-Cu Alloy with Hierarchical Network Structure as Enhanced Electrocatalysts for Formic Acid Oxidation[J]. International Journal of Hydrogen Energy, 2016, 41(16): 6773-6780.
[15] SHIN H U, LOLLA D, NIKOLOV Z, et al.Pd-Au Nanoparticles Supported by TiO2 Fibers for Catalytic NO Decomposition by CO[J]. Journal of Industrial and Engineering Chemistry, 2016, 33: 91-98.
[16] LI W J, TSAI S, WEY M Y.Positive Effects of a Halloysite-Supported Cu/Co Catalyst Fabricated by a Urea-Driven Deposition Precipitation Method on the CO-SCR Reaction and SO2 Poisoning[J]. Catalysis Science & Technology, 2021, 11(10): 3456-3465.
[17] YANG L, LI J, CAO G Q, et al.Flexible Monolithic Pt/CuO-Fe2O3/TiO2 Catalysts Integrated on Ti Mesh for Efficient NO Removal via CO-SCR Reaction[J]. Journal of Environmental Chemical Engineering, 2023, 11(6): 111262.
[18] TANG X Y, WANG J C, LI J, et al.In-Situ Growth of Large-Area Monolithic Fe2O3/TiO2 Catalysts on Flexible Ti Mesh for CO Oxidation[J]. Journal of Materials Science & Technology, 2021, 69: 119-128.
[19] AHMAD M M, MUSHTAQ S, AL QAHTANI H S, et al. Investigation of TiO2 Nanoparticles Synthesized by Sol-Gel Method for Effectual Photodegradation, Oxidation and Reduction Reaction[J]. Crystals, 2021, 11(12): 1456.
[20] GUO Z W, KANG X W, ZHENG X S, et al.PdCu Alloy Nanoparticles Supported on CeO2 Nanorods: Enhanced Electrocatalytic Activity by Synergy of Compressive Strain, PdO and Oxygen Vacancy[J]. Journal of Catalysis, 2019, 374: 101-109.
[21] LI X Y, WANG C, YANG J L, et al.PdCu Nanoalloy Decorated Photocatalysts for Efficient and Selective Oxidative Coupling of Methane in Flow Reactors[J]. Nature Communications, 2023, 14(1): 6343.
[22] GE Y Y, WANG X X, HUANG B, et al.Seeded Synthesis of Unconventional 2H-Phase Pd Alloy Nanomaterials for Highly Efficient Oxygen Reduction[J]. Journal of the American Chemical Society, 2021, 143(41): 17292-17299.
[23] DEMING C P, ZHAO A, SONG Y, et al.Alkyne- Protected AuPd Alloy Nanoparticles for Electrocatalytic Reduction of Oxygen[J]. ChemElectroChem, 2015, 2(11): 1719-1727.
[24] XIONG L, HUANG Y X, LIU X W, et al.Three- Dimensional Bimetallic Pd-Cu Nanodendrites with Superior Electrochemical Performance for Oxygen Reduction Reaction[J]. Electrochimica Acta, 2013, 89: 24-28.
[25] XU C X, LIU Y Q, WANG J P, et al.Nanoporous PdCu Alloy for Formic Acid Electro-Oxidation[J]. Journal of Power Sources, 2012, 199: 124-131.
[26] WU D F, XU H X, CAO D P, et al.PdCu Alloy Nanoparticle-Decorated Copper Nanotubes as Enhanced Electrocatalysts: DFT Prediction Validated by Experiment[J]. Nanotechnology, 2016, 27(49): 495403.
[27] CHEN D, XU L L, LIU H, et al.Rough-Surfaced Bimetallic Copper-Palladium Alloy Multicubes as Highly Bifunctional Electrocatalysts for Formic Acid Oxidation and Oxygen Reduction[J]. Green Energy & Environment, 2019, 4(3): 254-263.
[28] LI X Y, WANG C, YANG J L, et al.PdCu Nanoalloy Decorated Photocatalysts for Efficient and Selective Oxidative Coupling of Methane in Flow Reactors[J]. Nature Communications, 2023, 14(1): 6343.
[29] ZHANG Z Z, CHENG S F, LIU W Q, et al.Unraveling the Regulation of Mn in Cu-ZnOx Formation during Methanol Synthesis from Syngas over Cu/ZnO/Al2O3-Mn Catalysts[J]. Applied Catalysis B: Environmental, 2023, 338: 122985.
[30] WANG J Y, GAO F Y, DANG P H, et al.Recent Advances in NO Reduction with CO over Copper-Based Catalysts: Reaction Mechanisms, Optimization Strategies, and Anti-Inactivation Measures[J]. Chemical Engineering Journal, 2022, 450: 137374.
[31] TAKAGI N, ISHIMURA K, MIURA H, et al.Catalysis of Cu Cluster for NO Reduction by CO: Theoretical Insight into the Reaction Mechanism[J]. ACS Omega, 2019, 4(2): 2596-2609.
[32] SONG D Y, SVADLENAK S, BATHENA T, et al.PdCu Alloy Catalyst for Inhibition-Free, Low-Temperature CO Oxidation[J]. ChemCatChem, 2024, 16(1): e202301024.
[33] WANG Y F, ZHANG C B, LIU F D, et al.Well-Dispersed Palladium Supported on Ordered Mesoporous Co3O4 for Catalytic Oxidation of O-Xylene[J]. Applied Catalysis B: Environmental, 2013, 142: 72-79.
[34] DE LA TORRE U, URRUTXUA M, PEREDA-AYO B, et al. On the Cu Species in Cu/Beta Catalysts Related to DeNOx Performance of Coupled NSR-SCR Technology Using Sequential Monoliths and Dual-Layer Monolithic Catalysts[J]. Catalysis Today, 2016, 273: 72-82.
[35] MENG X L, MENG L K, GONG Y J, et al.Modifying Y Zeolite with Chloropropyl for Improving Cu Load on Y Zeolite as a Super Cu/Y Catalyst for Toluene Oxidation[J]. RSC Advances, 2021, 11(59): 37528-37539.
[36] ČAPEK L, DĚDEČEK J, WICHTERLOVÁ B, et al. Cu-ZSM-5 Zeolite Highly Active in Reduction of NO with Decane[J]. Applied Catalysis B: Environmental, 2005, 60(3/4): 147-153.
[37] GHOLAMI Z, LUO G H, GHOLAMI F.The Influence of Support Composition on the Activity of Cu: Ce Catalysts for Selective Catalytic Reduction of NO by CO in the Presence of Excess Oxygen[J]. New Journal of Chemistry, 2020, 44(3): 709-718.
[38] LAI S S, MENG D M, ZHAN W C, et al.The Promotional Role of Ce in Cu/ZSM-5 and in situ Surface Reaction for Selective Catalytic Reduction of NOx with NH3[J]. RSC Advances, 2015, 5(110): 90235-90244.
[39] ZHANG Y, ZHAO L, KANG M D, et al.Insights into High CO-SCR Performance of CuCoAlO Catalysts Derived from LDH/MOFs Composites and Study of H2O/SO2 and Alkali Metal Resistance[J]. Chemical Engineering Journal, 2021, 426: 131873.
[40] DONG L H, ZHANG L L, SUN C Z, et al.Study of the Properties of CuO/VOx/Ti0.5Sn0.5O2 Catalysts and Their Activities in NO + CO Reaction[J]. ACS Catalysis, 2011, 1(5): 468-480.
[41] HE Y J, LIU J, ZHANG G J, et al.Insights into the Structure-Activity Relationships of Highly Efficient CuCe Oxides for the Low Temperature CO Oxidation and CO- SCR[J]. Journal of the Energy Institute, 2022, 104: 142-155.
(下转第155页)
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）
PDF(12163 KB)
渝公网安备 50010702501715号 渝ICP备15012534号-3
