CO-SCR Performance and Reaction Mechanism of CuPd-TiO2/Ti Metal Mesh Catalyst

LIU Tingting; YANG Liu; LIU Fuhao; LI Xinyu; HE Hanze; LI Jing; LIU Baodan

doi:10.16490/j.cnki.issn.1001-3660.2025.15.012

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Surface Technology ›› 2025, Vol. 54 ›› Issue (15) : 134-144. DOI: 10.16490/j.cnki.issn.1001-3660.2025.15.012

Technology and Application

CO-SCR Performance and Reaction Mechanism of CuPd-TiO₂/Ti Metal Mesh Catalyst

LIU Tingting^{1, 2}, YANG Liu¹, LIU Fuhao^{1, 2}, LI Xinyu^{1, 2}, HE Hanze^{1, 2}, LI Jing^{1, 2, *}, LIU Baodan^{1, 2, *}

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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 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 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 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.

Key words

Cu-Pd alloy catalysts / metal mesh / CO-SCR / low-temperature activity / nitrogen oxides / in situ growth

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LIU Tingting, YANG Liu, LIU Fuhao, LI Xinyu, HE Hanze, LI Jing, LIU Baodan. CO-SCR Performance and Reaction Mechanism of CuPd-TiO₂/Ti Metal Mesh Catalyst[J]. Surface Technology. 2025, 54(15): 134-144 https://doi.org/10.16490/j.cnki.issn.1001-3660.2025.15.012

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Funding

Fundamental Research Funds for the Central Universities (N2229002); the Research and the Development Start-up Foundation of Foshan Graduate School of Innovation, Northeastern University (FSNEU20201016001, FSNEU20201016003); Scientific Research Project of Foshan Talents (200076622001, 200076622004)