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Extremely High emissions of Condensable Particulate Matter from Typical Diesel Vehicles Regulated by Exhaust Treatment System

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SSRN 2024年

作者： Liu, Anlin Shao, Yuankai Chen, Yuanzheng Xu, Jiaying Guo, Zihua Li, Zhenguo Wu, Di Wu, Jiwei Chang, Yulong Ma, Liang Li, Qing Chen, Jianmin Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention Department of Environmental Science and Engineering Fudan University Shanghai200433 China College of Carbon Neutrality Future Technology Sichuan University Sichuan Chengdu610065 China 20 Cuiniao Road Chenjia Town Chongming District Shanghai202162 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Co Ltd Tianjin300300 China

Condensable particulate matter (CPM) emissions from industrial plants have been extensively studied, but information regarding mobile sources remains elusive. This study provides the emission characteristics of CPMs under various engine loads through a series of carefully conducted heavy and light diesel bench experiments. The concentration of CPM in the vehicle exhaust, consisting mainly of organic matter, is much higher (p = 0.02) than that of filterable particulate matter, up to ten times higher. The major components of the organic CPMs are intermediate/semi-volatile organic compounds accounting for 94.8%, in which the alkanes are the predominant type of observed components. Furthermore, the post-treatment system (PTS) installed in the exhaust pipes exhibits increased efficiency in removing organic CPMs as the engine load rises, but the removal efficacy only achieves 72.7%−78.4% at high engine loads. Concurrently, the PTS application results in increased emissions of oxygen-containing organic compounds and inorganic species in CPMs. The newly formed inorganic CPM is mainly in the form of NH4+, accounting for 65.1%−96.7%, which is mainly attributed to the slipped NH3. These new findings underscore the importance of developing new PTSs to effectively remove CPMs and prevent NH3 slipping from diesel vehicles, especially in urban common scenarios. © 2024, The Authors. All rights reserved.

关键词： Ammonia

Influence of the Engine Drop-to-Idle Process on Regeneration Temperature, Filtration and Morphology Characteristics of Diesel Particulate Filters

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SSRN 2023年

作者： Cai, Zhizhou Yan, Fuwu Hu, Jie Wu, Hanming Liao, Jianxiong Wu, Yan Zheng, Shijie Li, Zhenguo Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan430070 China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of Technology Wuhan430070 China Hubei Research Center for New Energy & Intelligent Connected Vehicle Wuhan University of Technology Wuhan430070 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Tianjin300300 China

As emission regulations become increasingly stringent, the durability of diesel aftertreatment system is another concern in addition to the excellent purification capacity. Under extreme circumstances, the engine may drop to idle (DTI) sharply and if active regeneration occurs during this period, there is a risk of DPF cracking and melting due to the huge accumulation of soot combustion heat. In this study, regeneration performances, including temperature and transient emission characteristics of cordierite DPF during a DTI process were investigated. The temperature distribution is highly nonuniform, with the peak temperature appearing in the middle ring of the DPF monolith's rear end. As the soot load reached 7 g/L, extensive DPF cracks can be observed and the PN emission dramatically exceeded the regulatory limit. In addition, the evolution of a porous wall's macro morphology and micro pore structure was examined. Numerous microcracks were formed and the wall surface became rougher and more irregular. The substrate's bulk density, average pore diameter, and permeability decreased whilst its total pore volume, total pore area, tortuosity, and porosity increased. The findings contribute to a better comprehension of DPF designs, regeneration strategies and durability improvements. © 2023, The Authors. All rights reserved.

关键词： Morphology

Introducing "Smart" Ni Co-Cations to Simultaneously Maintain a High Nox Uptake Capacity and Improve the Hydrothermal Stability of Pd/Ssz-13 for Low-Temperature No Adsorption

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SSRN 2023年

作者： Cai, Jinhuang Zhao, Huawang Wu, Xiaomin Huang, Zhiwei Shen, Huazhen Cui, Kai Li, Zhenguo Jing, Guohua Schwank, Johannes W. Department of Environmental Science & Engineering College of Chemical Engineering Huaqiao University Fujian Xiamen361021 China Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Co. Ltd. Tianjin300300 China Institute of Engineering Technology Sinopec Catalyst Co.Ltd. Beijing101100 China

The hydrothermal stability of Pd/SSZ-13 needs to be improved, particularly when subjected to hydrothermal aging (HTA) at temperatures exceeding 850 °C. Generally, incorporating co-cations in coordination with thermally stable Al pair sites enhances the Pd/SSZ-13 stability. However, this approach significantly reduces the NO storage capacity of fresh samples due to competition between co-cations and Pd2+ ions, leading to the sintering Pd2+ to PdO. In this study, we demonstrate that the "smart" behavior of Ni2+ breaks this activity-hydrothermal stability trade-off. We discovered that in the as-prepared Pd/Ni/SSZ-13 sample, Ni2+ ions predominantly occupied single Al sites as Z[Ni(OH)]+. The abundant ion-exchange sites (with single Al sites accounting for 70% of the total framework Al) easily accommodated both Pd2+ and Ni2+ ions, mitigating cation competition. The presence of Ni2+ only marginally reduced the NOx storage capacity of Pd/SSZ-13, with the NOx/Pd ratio decreasing from 0.78 to 0.70. During HTA at 850°C, Z[Ni(OH)]+ gradually transformed into the more thermally stable Z2Ni2+ coordinated to Al pair sites, effectively limiting dealumination. This well-preserved structure maintained a larger number of ion-exchange sites to accommodate Pd2+ ions while simultaneously facilitating the PdO hydrolysis to Pd2+ ions on Brønsted acid sites in Pd/Ni/SSZ-13 during HTA. Consequently, the NOx storage capacity increased (the NOx/Pd ratio rose from 0.70 for the fresh sample to 0.75 for the aged sample). In contrast, undoped Pd/SSZ-13 experienced nearly complete deactivation after HTA (NOx/Pd=0.2). These findings offer valuable insights for rationally designing Pd/SSZ-13 materials that exhibit both high NO uptake capacity and robust hydrothermal stability. © 2023, The Authors. All rights reserved.

关键词： Palladium

Lumped Model for Evaluating Dynamic Filtration and Pressure Drop Behaviours in Diesel Particulate Filters

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SSRN 2024年

作者： Cai, Zhizhou Yan, Fuwu Shao, Yuankai Liao, Jianxiong Wu, Yan Zheng, Shijie Li, Yu xuan Hu, Jie Wang, Zhihong Li, Zhenguo Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan430070 China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of Technology Wuhan430070 China Hubei Research Center for New Energy & Intelligent Connected Vehicle Wuhan University of Technology Wuhan430070 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Tianjin300300 China

Particulate matter (PM) emitted from diesel vehicles poses significant risks to global climate, environment, and human health. Diesel particulate filters (DPF) are currently the only effective aftertreatment device for PM emissions reduction and it is important to reflect the DPF filtration and pressure drop performance by numerical method. This study established and validated a lumped model based on the spherical packed beds theory and Darcy’s law. The PM effective density was firstly used to obtain the PM loading rate for model input. The model described the dynamic PM filtration process in DPF, predicting real-time characteristics such as wall porosity, soot load, and pressure drop with improved accuracy. The effects of channel characteristics, monolithic size, and exhaust conditions on filtration and pressure drop performance were then investigated. The results showed that an increase in cell density, wall thickness, DPF length and diameter is beneficial for increasing filtration efficiency, while DPF inlet temperature and exhaust mass flow rate have adverse effect. Wall thickness, DPF diameter and exhaust flow rate have especially significant impact on total pressure drop. The results contributes to a better understanding of the PM filtration process and provide a theoretical basis for the DPF structural optimization. © 2024, The Authors. All rights reserved.

关键词： Pressure drop

High-Performance Strategy and Degradation Mechanism of Cezrvox Catalysts for Nox Reduction

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SSRN 2024年

作者： Li, Guobo Cai, Yining Yan, Jie Hou, Yuehan Chen, Hunan Zou, Yu Liu, Wenming Li, Zhenguo Lu, Shengyong Peng, Honggen School of Resources and Environment Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China School of Chemistry and Chemical Engineering Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Tianjin300300 China State Key Laboratory for Clean Energy Utilization Institute for Thermal Power Engineering Zhejiang University Hangzhou310027 China

The denitrification (deNOx) performance of catalysts is affected directly by redox ability and surface acidity,and regulating the balance between both of which is a major step toward enhancing the performance of *** CeZrOx catalyst has garnered widespread attention in the field of deNOx due to its excellent oxygen storage capacity. This study uses VOx as an acid promoter to adjust the redox centers and acidity sites on the CeZrOx catalyst, utilizing the synergistic effect of both to demonstrate its optimal deNOx performance. The experimental results indicate that doping an appropriate amount of VOx can effectively enhance the NH3-SCR activity of Ce0.60Zr0.40Ox, while also improving its resistance to SO2 and H2O. Characterization results confirm that, the surface active oxygen species on Ce0.50Zr0.40V0.10Ox increase and V doping enhances the catalyst's redox properties comparing with Ce0.60Zr0.40Ox, which obtains more Brønsted and Lewis acid sites, adjusting the balance between the redox centers and acidity sites, thus playing a synergistic promoting role. Ce0.50Zr0.40V0.10Ox possesses the lowest apparent activation energy (Ea), enhancing the adsorption capability for NH3 and increasing the reaction rate of adsorbed NH3 and gaseous NO + O2, thereby exhibiting optimal deNOx performance. The surface VOx and ZrOx would provide adsorption sites for gas molecules, utilizing the synergistic effect of both to demonstrate its optimal deNOx performance on ZrVOx-CeO2 surface. This provides valuable insight for the preparation of new and efficient deNOx catalysts using the strategy of synergistically promoting the oxygen reduction sites and acidity sites. © 2024, The Authors. All rights reserved.

关键词： Catalysts

High Alkali Resistance Selective Catalytic Reduction of Nox by Releasing Brønsted Acid Sites

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SSRN 2023年

作者： Chen, Lei Zou, Yu Li, Yonglong Li, Guobo Liu, Wenming Zhang, Hongxiang Lu, Shengyong Li, Zhenguo Zhang, Shule Peng, Honggen School of Resources and Environment Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China School of Chemistry and Chemical Engineering Nanchang University 999 Xuefu Road Jiangxi Nanchang330031 China State Key Laboratory for Clean Energy Utilization Institute for Thermal Power Engineering Zhejiang University Hangzhou310027 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Tianjin300300 China School of Chemical Engineering Nanjing University of Science and Technology Nanjing210094 China

The CeO2–WO3 catalyst used for NOx abatement in biomass boiler combustion was prone to severe deactivation due to the high alkali metal content in exhaust gas. Enhancing the alkali resistance of the CeO2–WO3 catalyst was crucial for its practical application. In this study, the CeO2–WO3/MCM-22 catalysts were synthesized via a simple impregnation method, resulting in a minimal reduction in catalyst activity after 1 wt.% K2O poisoning. The anti-K poisoning mechanism of CeO2–WO3/MCM-22 catalyst was studied through experimental methods such as XRD, HRTEM, XPS, in situ DRIFTs and DFT calculations. The results demonstrated that the acid sites of lamellar MWW-Type molecular sieve MCM-22 acted as sacrificial sites, effectively trapping the alkali poisoning and protecting the CeO2–WO3 active component. Compared with CeO2–WO3 catalyst, the Brønsted acid sites on the cerium tungstate occupied by foreign K, were liberated as K element preferentially bound to the molecular sieve MCM-22. © 2023, The Authors. All rights reserved.

关键词： Cerium oxide

Investigation of Diesel Particulate Filter Performance Under Typical Failure Conditions

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SSRN 2024年

作者： Yan, Fuwu Cai, Zhizhou Li, Zhenguo Zhu, Lei Chen, Peng Zheng, Shijie Wu, Yan Li, Yuxuan Hu, Jie Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan430070 China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of Technology Wuhan430070 China Hubei Research Center for New Energy & Intelligent Connected Vehicle Wuhan University of Technology Wuhan430070 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Tianjin300300 China Kailong High Technology Company Limited Wuxi214174 China

Diesel particulate filter (DPF) is one of the most effective particulate reduction components in diesel engine aftertreatment systems. However, prolonged utilization of a DPF might result in a deterioration in performance or even failure, such as ash-clogging, melting, breakage, and catalyst deactivation. It is crucial to conduct research on DPF performance degradation across a series of partially failed conditions. In this study, the morphology and chemical composition of the ash in the DPF samples were characterized. The effects of degree-varying clogging and unplugged-breakage failure on exhaust characteristics as well as DPF temperature, filtration and pressure drop characteristics were investigated. A canonical correlation analysis (CCA) was finally conducted considering the sensitivity differences between DPF performance parameters and failure index parameters. The results indicate that the DPF temperature difference and filtration efficiency are mainly related to the ash loading and breakage index, while the pressure difference is most affected by the exhaust mass flow rate. Increasing the DPF inlet temperature declines the pressure drop and slightly increases the filtration efficiency and DPF temperature difference, but these effects are not significant. These findings contribute to the prediction of DPF performance in partially failed states and the development of DPF failure diagnosis methods. © 2024, The Authors. All rights reserved.

关键词： Drops

Generating Silicon-Rich AFX Zeolite Using Rigid Diquaternary Alkylammonium Structure Directing Agent Towards Stable Selective Catalytic Reduction of NOx by NH3

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SSRN 2023年

作者： Shi, Zheru Sun, Han Wang, Lei Deng, Quanzheng Gong, Chen-Xin Han, Lu Li, Kaixiang Deng, Wei Zhu, Yi-An Li, Zhenguo Chen, Haijun Zhu, Kake UNILAB State Key Laboratory of Chemical Engineering School of Chemical Engineering East China University of Science and Technology 130 Meilong Road Shanghai200237 China Department of Electronics Tianjin Key Laboratory of Photo-Electronic Thin Film Device and Technology Nankai University Tianjin300071 China School of Chemistry and Molecular Engineering Nanjing Tech University South Puzhu Rd. 30 Nanjing211816 China School of Chemical Science and Engineering Tongji University Shanghai200092 China National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology & Research Center Co. Ltd Tianjin300300 China School of Optoelectronic Materials and Technology Jianghan University Wuhan430056 China

New synthetic protocols to manipulate Si/Al ratios of small pore zeolites hold promise to find better selective NOx reduction catalyst using NH3 as reducing agent (NH3-SCR). AFX zeolite as NH3-SCR catalyst is currently impeded by the insufficient hydrothermal stability owing to the low Si/Al ratio. In this contribution, we report the synthesis of AFX zeolite using N,N-(1,4-phenylenebis(methylene))bis(N,N-diethylethanaminium) as organic structure directing agent (OSDA) to increase the framework Si/Al ratio to 7.8, giving rise to a marked enhancement of hydrothermal stability to withstand hydrothermal aging at 850 oC for up to 10 h. The increase in Si/Al ratio for AFX zeolite minimizes catalytic cycle driven by Brønsted acid site and broadens high temperature operation window (150-520 oC) for Cu-exchange catalyst. Moreover, the hydrothermally aged Cu-AFX catalyst exhibits comparable catalytic activity to that of the fresh catalyst owing to Cu re-distribution that reinforced the framework stability. © 2023, The Authors. All rights reserved.

关键词： Ammonia

Effect of electric diesel particulate trap on particulate emission characteristics of light-duty diesel engine

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IOP Conference Series: Earth and Environmental Science 2020年第4期510卷

作者： Zhenguo Li Kunyou Jue Diming Lou Xianglin Zhong Yunhua Zhang National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology and Research Center Co. Ltd 68 Xianfeng East Road Tianjin China School of Automotive Studies Tongji University 4800 Cao'an Road Shanghai China

Based on the principle of corona discharge and electrostatic adsorption, an electric diesel particulate trap (EDPT) with high-voltage negative corona electrode structure was designed. The effect of EDPT on particulate emission characteristics of light-duty diesel engine was investigated based on engine bench test platform. The results show that at the external characteristics operating point of the engine, the trapping efficiency of EDPT for particulate number (PN) is 98.4%, and the trapping efficiency for particulate mass (PM) is 95.0%. With the increasing of exhaust flow, the trapping efficiency of EDPT for PN and PM both decreases slightly. At the load characteristics when engine speed is 1800 rmin−1, the trapping efficiency of PN and PM by EDPT are 98.9% and 95.1%, and the trapping efficiency does not change significantly with the increase of load and temperature. The effects of EDPT and DOC (Diesel oxidation catalyst)+diesel particulate filter (DPF) device on engine backpressure and particulate trapping efficiency are compared. The results show that the effect of using EDPT on engine exhaust backpressure is much lower than DOC+DPF, and the trapping efficiency for PN and PM is lower than that of DOC+DPF. From the perspective of trapping efficiency and device size, EDPT is more suitable for the exhaust gas treatment of construction machinery, agricultural machinery and factory fixed source diesel engines.

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