Abstract

Objective To enhance the regeneration efficiency of diesel particulate filters （DPFs）， it is necessary to increase the lattice oxygen mobility and active oxygen content，thus improving the soot oxidation capacity of the catalyst at medium and low temperatures. Therefore， it is critical to develop an efficient and cost-effective catalyst that can facilitate soot oxidation under these conditions.

Methods In this study， pure metal oxides， CePrO_x，and CePrMnO_x catalysts were synthesized using the cetyltrimethylammonium bromide （CTAB） assisted co-precipitation method. The physical and chemical properties of these catalysts were characterized by various analytical techniques. Their structure and morphology， defect degree， reduction ability， oxidation ability， and mech-anism were systematically studied.

Results and Discussion Based on the characterization and experimental results， the catalytic oxidation activity test curves of soot showed that co-doping with Pr and Mn increased lattice oxygen mobility and reactive oxygen content in the catalysts. Specifically， the CePrMnO_x catalyst exhibited superior low-temperature oxidation ability for soot， and its t₁₀ and t₅₀values were 85 ℃ and 67 ℃ lower than those of CeO₂， respectively. X-ray diffraction （XRD） results confirmed that Pr and Mn elements were successfully doped into CeO₂ lattice， leading to lattice distortion.This distortion， which altered the lattice symmetry and oxygen ion migration pathways， was likely the key factor in improving lattice oxygen mobility. Nitrogen adsorption-desorption experiments showed that the CePrMnO_x catalyst hada larger specific surface area and pore volume， suggesting more active sites for reactants to interact with， thus improving the catalytic efficiency. SEM results revealed the presence of nanorods in the CePrMnO_x catalyst， which improved the contact efficiency of active sites and further enhanced the catalytic performance. Raman and temperature-programmed reduction （TPR） results showed that the CePrMnO_x catalyst hada higher oxygen vacancy concentration and stronger reduction ability. X-ray photoelectron spectroscopy （XPS） results suggested that this was due to the higher content of Ce³⁺， Mn³⁺， and surface reactive oxygen species in the CePrMnO_x catalyst. In situ diffuse reflectance infrared Fourier transform spectroscopy（DRIFT） results showed that carbonates were the main intermediate reaction products for both CePrO_x and CePrMnO_x catalysts.The bidentate carbonates on the surface of the CePrO_x catalyst did not fully participate in the reaction， thus covering the active sites and limiting the improvement of catalytic activity. In contrast， the CePrMnO_x catalyst， with its higher active oxygen content and oxygen vacancy concentration，promoted carbonate conversion more effectively， thus improving the catalytic efficiency.

Conclusion 1）The CTAB-assisted co-precipitation method not only maintains the cubic fluorite structure of CeO₂ but also successfully introduces Pr and Mn elements into the CeO₂lattice. This co-doped catalyst exhibits a larger specific surface area and has more active sites for reactant interaction， thus improving catalytic activity. Moreover， this method enhances the redox capacity of the catalyst， which is particularly important for catalytic oxidation reactions.It promotes the activation and transfer of oxygen， thereby improving the catalytic efficiency. 2）Mn doping has a significant impact on catalyst performance. The introduction of Mn enhances the oxygen migration ability of the catalyst and increases the content of chemisorbed oxygen on the surface. Efficient oxygen migration is vital for soot oxidation. Additionally， higher surface chemisorbed oxygen content means more oxygen molecules can be adsorbed on the catalyst surface， providing more reactive oxygen species for oxidation reactions. These characteristics collectively improve the catalyst performance in soot oxidation reactions， making it more efficient at low temperatures. 3）During soot oxidation， bidentate carbonates are the main reactive species. However， bidentate carbonates on the surface of the CePrO_x catalyst may cover active sites， reducing catalytic activity. This occurs because the adsorption of bidentate carbonates may hinder reactant contact with the active site. In contrast， the CePrMnO_x catalyst， due to its optimized surface properties and enhanced oxygen migration capacity， can convert bidentate carbonates more efficiently.This reduces active site coverage and improves catalyticactivity. These findings indicate that the CePrMnO_x catalyst performs better in soot oxidation， which is significant for improving catalytic efficiency and reducing environmental pollution.

Keywords： cerium-based catalyst； soot oxidation； doping； active oxygen

Get Citation:ZHAO Xinyi， REN Yichen， JIANG Ruolan， et al. Performance and mechanism of cerium-praseodymium-manganese （CePrMnO_x） solid solution in catalytic soot combustion［J］. China Powder Science and Technology， 2025， 31（4）： 1-13.

Received: 2025-01-06 .Revised: 2025-04-22 ,Online: 2025-06-03

Funding Project:国家自然科学基金项目，编号： 21777055； 山东省自然科学基金项目，编号： ZR2024QE354， ZR2023MB100， ZR2021MB063；福建省自然科学基金项目，编号：2023J05090。

First Author:赵心怡（2001—），女，硕士生，研究方向为环境功能材料开发与应用。E-mail：3302289639@qq.com。

Corresponding Author:王仲鹏（1978—），男，教授，博士，博士生导师，科技部国家火炬计划专家，山东省优秀中青年科学家，山东省科技人才，研究方向为大气污染控制与催化技术。E-mail：chm_wangzp@ujn.edu.cn。

DOI：10.13732/j.issn.1008-5548.2025.04.015

CLC No:TB4； TQ426   Type Code: A

Serial No:1008-5548（2025）04-0001-13