Research on the Mechanism of Catalyst Activity Decay in Catalytic Converters

  Industry News     |      2024-04-19


As a key component of automotive exhaust treatment, the catalytic converter's activity directly affects the quality of exhaust emissions and the effectiveness of environmental protection. However, catalysts may experience activity decay during use, which affects the performance and lifespan of catalytic converters. This article aims to investigate the mechanism of catalytic converter catalyst activity attenuation in depth, in order to provide theoretical basis for the optimization design and use of catalysts. By combining literature review, experimental research, and theoretical analysis, the main causes and influencing factors of catalyst activity degradation were explored, and corresponding improvement measures were proposed.

Keywords: catalytic converter, catalyst, activity decay, mechanism research

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1、 Introduction


With the rapid development of the automotive industry, the issue of automobile exhaust emissions is becoming increasingly prominent. As an important component of automotive exhaust treatment systems, the performance of catalytic converters is directly related to the compliance of exhaust emissions. Catalysts are the core of catalytic converters, and their activity determines the efficiency and effectiveness of catalytic reactions. However, in actual use, the activity of the catalyst will gradually decline, leading to a decrease in the performance of the catalytic converter and even failure. Therefore, in-depth research on the mechanism of catalytic converter catalyst activity decay is of great significance for improving catalyst performance and extending the service life of catalytic converters.


2、 The main reasons for the decline of catalyst activity


Thermal inactivation

During the use of catalysts, their crystal structure may change due to the influence of high-temperature environments, resulting in a decrease or deactivation of active components. In addition, high temperatures may also accelerate the sintering and agglomeration phenomena on the catalyst surface, further reducing the activity of the catalyst.


Chemical poisoning

Impurity elements such as sulfur and phosphorus in the exhaust gas will react chemically with the active components on the catalyst surface, forming stable compounds, thereby reducing the activity of the catalyst. In addition, heavy metal ions in the exhaust may also deposit on the surface of the catalyst, blocking the active sites and causing catalyst poisoning and deactivation.


Carbon deposition phenomenon

The unburned hydrocarbons in the exhaust gas undergo polymerization reactions on the catalyst surface, forming carbon deposits. Carbon deposition will cover the active sites of the catalyst, hinder the progress of catalytic reactions, and thus reduce the activity of the catalyst.


Hydrothermal deactivation

Catalysts may undergo hydrothermal deactivation in humid environments, especially under high temperature and humidity conditions. Water molecules react with the active components on the surface of the catalyst, causing loss or structural changes of the active components, thereby reducing the activity of the catalyst.


3、 Factors affecting the attenuation of catalyst activity


Composition and structure of catalysts

The activity of catalysts is closely related to their composition and structure. Catalysts of different components have different catalytic performance and stability. In addition, factors such as the crystal structure, specific surface area, and pore size distribution of the catalyst can also affect its activity.


Operating conditions

The operating conditions of catalytic converters, such as temperature, pressure, and airspeed, have a significant impact on the activity of the catalyst. Excessive or insufficient temperature can lead to a decrease in catalyst activity. Meanwhile, changes in pressure and airspeed can also affect the reaction rate and selectivity of the catalyst surface.


Exhaust gas composition

The components in exhaust gas are complex and varied, and different components have varying effects on the activity of catalysts. For example, impurities such as sulfur and phosphorus can cause catalyst poisoning and deactivation, while unburned hydrocarbons may cause carbon deposition.


4、 Improvement measures for catalyst activity attenuation


Optimize catalyst composition and structure

By adjusting the composition and structure of the catalyst, its ability to resist poisoning, carbon deposition, and hydrothermal deactivation can be improved. For example, introducing rare earth elements and other additives can improve the crystal structure and surface properties of catalysts, and enhance catalytic activity.


Improve operating conditions

Reasonably control the operating conditions of the catalytic converter, avoid high or low temperatures, maintain appropriate pressure and airspeed to reduce catalyst activity decay.


Tail gas pretreatment

Before the exhaust gas enters the catalytic converter, pre-treatment is carried out to remove impurities such as sulfur and phosphorus, as well as unburned hydrocarbons, to reduce the risk of catalyst poisoning and carbon deposition.


Catalyst regeneration technology

Research the regeneration technology of catalysts, remove carbon deposits and toxic substances on the surface of catalysts through physical or chemical methods, and restore their activity.


5、 Conclusion and Outlook


The mechanism of catalytic converter catalyst activity decay is a complex issue, involving multiple aspects such as catalyst composition, structure, operating conditions, and exhaust gas composition. This article explores the main causes and influencing factors of catalyst activity degradation through review and experimental research, and proposes corresponding improvement measures. However, the current research on the mechanism of catalyst activity decay is still not in-depth enough, and further work is needed in the following areas in the future:


Thoroughly study the micro mechanism of catalyst activity attenuation and reveal the essential reasons for catalyst deactivation.

Strengthening the characterization technology research of catalysts, providing strong support for the optimization design and performance evaluation of catalysts.

Explore new catalyst materials and preparation processes to improve the activity and stability of catalysts.

Carry out research and application of catalyst regeneration technology to extend the service life of catalysts and reduce usage costs.

In summary, the study of the mechanism of catalytic converter catalyst activity decay is a challenging and practical topic. Through in-depth research and continuous innovation, it is expected to provide new impetus and support for the development of automotive exhaust treatment technology.