Authors: Jiaxing Li | Chuan Gao | Yunpeng Long | Yifan Li | Houlin Wang | Yue Peng | Junhua Li
Source: Chinese Science Bulletin (Chinese Version) (article, 2024-08-01)
Field: Materials Science — Materials Chemistry

Research status and prospects on key materials for diesel vehicle exhaust aftertreatment system <p indent="0mm">Diesel vehicle exhaust aftertreatment technology is a cornerstone in the ongoing effort to meet increasingly stringent emission regulations and achieve green, low-carbon transportation. The enforcement of the China VI standards has significantly reduced pollutant emissions, showcasing the effectiveness of current aftertreatment technologies. However, despite these advancements, considerable challenges remain in further enhancing the efficiency and managing the costs associated with these technologies. The need for continuous improvement is driven by the evolving regulatory landscape and the global push for sustainability. New materials and technological advances have emerged in recent years, offering fresh strategies for resolving these persistent challenges. This analysis aims to provide a thorough overview of the most recent developments in key catalysts used in the exhaust aftertreatment systems of diesel vehicles. This review delves into the innovative application of advanced catalytic materials within core systems, including diesel oxidation catalysts (DOCs), diesel particulate filters (DPFs), selective catalytic reduction (SCR) catalysts, and ammonia slip catalysts (ASC). These systems all play a critical role in the overall performance of diesel exhaust aftertreatment, and their optimization is essential to meet increasingly stringent emission standards. This review evaluates the possibility of several catalytic materials in practical, real-world applications by carefully examining the structural design, active component properties, and underlying mechanisms by which these materials enhance exhaust gas purification reactions. The review highlights the importance of the synergistic interaction between the four conventional aftertreatment technologies. For instance, DOCs produce carbon monoxide (CO) and nitrogen dioxide (NO<sub>2</sub>) through the oxidation of hydrocarbons, which is crucial for enhancing the reaction efficiency of both DPFs and SCR systems. However, DPFs are highly effective in capturing soot and reducing the energy consumption typically associated with regeneration processes through passive regeneration. The SCR system works closely with ASC to efficiently reduce nitrogen oxides (NO<italic>x</italic>) while preventing ammonia slip, a common issue in aftertreatment systems. The complex interactions between these units must be considered throughout the design and optimization of the entire exhaust treatment system to achieve optimal treatment performance and comply with strict emission requirements. Advancements in catalyst development have led to more efficient, cost-effective, and sustainable materials. However, further research is warranted to enhance the scientific understanding of these systems, especially using advanced characterization techniques. <italic>In-situ</italic> technologies offer high precision in observing dynamic changes at active sites. The energetic pathways of elementary processes at active sites can be determined by leveraging the powerful data processing capabilities of machine learning in conjunction with molecular dynamics simulations and Density Functional Theory (DFT) calculations. This method will also uncover new descriptors of structure-activity relationships, guiding the design of catalysts with superior low-temperature activity, durability, selectivity, and regeneration efficiency. Future plans call for tighter regulations on pollutants, including N<sub>2</sub>O and NH<sub>3</sub>, due to the expected introduction of Euro 7 standards and China VII emission requirements. These regulations will drive further innovation in exhaust treatment technologies. Future research should focus on developing multi-pollutant control technologies. For example, multifunctional catalysts capable of reducing NO<italic>x</italic>, decomposing N<sub>2</sub>O, and oxidizing NH<sub>3</sub> could be vital in meeting China VII standards. To sum up, this review offers a comprehensive analysis of the state of diesel vehicle exhaust aftertreatment technology today, highlighting the vital role that key materials will play in fostering future innovation. It underscores the importance of ongoing research and development efforts to meet evolving regulatory demands, enhance system performance, and ensure the sustainability of diesel exhaust management systems. Medicine Catalytic Processes in Materials Science ; Advanced Combustion Engine Technologies ; Biodiesel Production and Applications