The deactivation mechanism of catalytic converters and its solution strategies

  Industry News     |      2024-04-19

As a core component of automotive exhaust treatment, catalytic converters have a direct impact on the quality of automotive exhaust emissions. As a key component of catalytic converters, the activity of catalysts directly determines the efficiency of catalytic converters. However, catalysts may experience deactivation during use, leading to a decrease in catalytic converter performance. This article aims to investigate the deactivation mechanism of catalytic converters and propose corresponding solutions, in order to provide theoretical support for improving the activity and stability of catalysts.


With the rapid development of the automotive industry, the problem of automobile exhaust emissions is becoming increasingly serious. As a key technology in exhaust gas treatment, catalytic converters can effectively reduce the emission of harmful substances in exhaust gas. However, catalysts are affected by various factors during use, leading to a gradual decrease in their activity or even complete deactivation. Therefore, in-depth study of the deactivation mechanism of catalytic converters is of great significance for improving the performance of catalysts and extending their service life.


2、 Deactivation mechanism of catalytic converter catalyst


Thermal inactivation

When catalysts work in high-temperature environments, their crystal structure may change, leading to a decrease or deactivation of active components. In addition, high temperatures may also lead to sintering and agglomeration on the surface of the catalyst, further reducing its activity. Thermal deactivation is one of the main reasons for catalyst deactivation, especially during high engine load operation, where the temperature inside the catalytic converter rapidly increases, exacerbating the thermal deactivation 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. Chemical poisoning is another important cause of catalyst deactivation, especially in areas with high fuel sulfur content, where catalyst chemical poisoning is more severe.


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. The phenomenon of carbon accumulation is particularly evident during low-speed operation or cold start of the engine, as the fuel mixture is richer and the content of unburned hydrocarbons is higher in these situations.


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. Hydrothermal deactivation usually occurs when the car is driving in damp or rainy areas, or during the cold start stage of the engine, when the temperature inside the catalytic converter is lower and the influence of water molecules is greater.

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3、 Solution strategies for catalyst deactivation in catalytic converters


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. In addition, optimizing the pore structure of the catalyst and increasing the specific surface area can help increase the number of active sites, thereby improving the performance of the catalyst.


Improve operating conditions

Reasonably control the operating conditions of catalytic converters, such as temperature, pressure, airspeed, etc., to reduce the possibility of catalyst deactivation. In high-temperature environments, by optimizing the engine's cooling and exhaust systems, the temperature inside the catalytic converter can be reduced, thereby slowing down the thermal deactivation of the catalyst. At the same time, optimize the fuel injection and ignition system, reduce the content of impurities such as sulfur and phosphorus in the exhaust, and reduce the chemical poisoning phenomenon of the catalyst.


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. For example, using adsorbents or catalysts to purify exhaust gas, removing harmful components before entering the catalytic converter.


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. The regeneration technology includes thermal regeneration, chemical regeneration, and mechanical regeneration, and the specific selection should be based on the type of catalyst and the reason for deactivation.


The deactivation of catalytic converters is a complex process that involves multiple factors. This article analyzes the mechanism of catalyst deactivation and proposes corresponding solutions. However, the current research on the deactivation mechanism of catalysts is still not in-depth enough, and further work is needed in the following areas in the future:


Strengthen the basic research on the deactivation mechanism of catalysts, and reveal the essential reasons and processes of catalyst deactivation.

Research new catalyst materials and preparation processes to improve the activity and stability of catalysts and reduce the risk of deactivation.

Develop efficient catalyst regeneration technology to extend the lifespan of catalysts and reduce usage costs.

In summary, the deactivation mechanism and solution strategies of catalytic converters are challenging and practical topics. Through in-depth research and continuous innovation, it is expected to provide new impetus and support for the development of automotive exhaust treatment technology.