VOCs Control in The Auto Repair Industry: From Traditional Dilemmas To A New Path of Low-Temperature Catalysis

VOCs Control in the Auto Repair Industry: From Traditional Dilemmas to a New Path of Low-Temperature Catalysis

I. Background: The Urgency of VOCs Control and Industry Challenges

Volatile organic compounds (VOCs) are not only important precursors of PM2.5, but also a key driving force for the formation of ozone (O₃). Under the influence of sunlight, they undergo complex photochemical reactions with nitrogen oxides (NOx) and other substances, which can easily lead to regional ozone pollution and photochemical smog, seriously threatening the atmospheric environment and human health. In view of this, the control of VOCs has become a core task in global air pollution prevention and control.

With the development of China's economy and society, the number of motor vehicles has been increasing continuously. Data shows that by the end of 2024, the global motor vehicle population has exceeded 1.5 billion, with the number of cars reaching 1.3 billion. In China alone, the number of motor vehicles is also among the highest in the world. The huge number of cars has given rise to a huge auto repair market - currently, there are approximately 440,000 auto repair shops of all kinds in China. However, behind this prosperity lies a serious environmental hazard: the auto repair painting process (including paint mixing, sanding, painting, drying and cleaning, etc.) is a major source of medium and low concentration VOCs emissions. The instantaneous emission concentration peak of the spray-bake-dry process can reach 500mg/m³, and the composition is complex (mainly including benzene series, esters, alkanes and halogenated hydrocarbons, etc.).

What is even more challenging is that the auto repair industry is characterized by a large number of small and scattered entities, which makes traditional end-of-pipe treatment face huge regulatory and technical adaptation difficulties.

II. Review of the Current Situation: Limitations of Traditional Governance Techniques

For a long time, in the automotive repair and painting industry, the "pre-treatment + end-of-pipe treatment" combined process has been widely adopted for the treatment of painting waste gas, mainly including activated carbon adsorption, catalytic combustion, and biological methods. However, in the face of increasingly strict environmental protection standards and the demand of small and medium-sized enterprises for cost reduction and efficiency improvement, these traditional processes have revealed obvious shortcomings:

1. Activated carbon adsorption method: Although the initial investment is relatively low, it has the problems of short adsorption saturation cycle and frequent replacement. This not only leads to high operation and maintenance costs but also generates a large amount of hazardous waste (spent activated carbon), increasing the burden of compliance disposal and environmental risks for enterprises.

2. Catalytic combustion method (RCO): This technology has a high purification efficiency, but it usually requires preheating the exhaust gas to 260℃ to 350℃. For small and medium-sized auto repair shops with large fluctuations in air volume and relatively low concentrations, the high equipment investment and energy consumption costs often make it unattractive.

3. Biological method: This method has low operating costs, but it has strong selectivity for the types and concentrations of pollutants in the intake air and is mainly suitable for exhaust gases with good water solubility (such as water-based paint). In the face of the complex components of mixed solvent-based paint emissions in the auto repair industry, its applicability is greatly reduced.

In recent years, as inefficient processes such as simple UV photolysis and plasma have been gradually phased out, how to achieve efficient purification under low-temperature conditions while taking into account the economic affordability of small and medium-sized enterprises has become a technical bottleneck that urgently needs to be broken through in the VOCs treatment of the auto repair industry.

III. Technical Outlook: Application Potential of Ozone Synergistic Low-Temperature Catalytic Technology

In response to the above-mentioned pain points, the ozone-assisted low-temperature catalytic oxidation technology shows broad application prospects. This technology utilizes the strong oxidizing property of ozone as an auxiliary means, in combination with a catalyst to activate the oxidation reaction at relatively low temperatures, thereby achieving the deep degradation of VOCs.

Compared with traditional high-temperature combustion or single adsorption processes, this technology is expected to ensure a high removal rate while significantly reducing energy consumption and investment costs. It not only provides a new approach to solving the problem of spray painting waste gas treatment in the auto repair industry, but also is expected to become a preferred technical solution for small and medium-sized auto repair enterprises to achieve compliance emissions and economic operation in the future.