In view of the development of volatile organic waste gas treatment technology, the volatile organic waste gas treatment technology is first introduced, including the treatment of volatile organic waste gas by combustion method, such as direct combustion method, catalytic combustion method for treating volatile organic waste gas, biological treatment Volatile organic waste gas and adsorption process for the treatment of volatile organic waste gas, the development and application of volatile organic waste gas treatment technology, the microwave catalytic oxidation technology, activated carbon fiber treatment technology and biological treatment technology, and the introduction of volatile organic waste gas Application in governance, application of nanomaterial purification technology and application of membrane-based absorption purification technology in volatile organic waste gas treatment.
Volatile organic waste gas (hereinafter referred to as VOCs) is a harmful gas whose boiling point is close to the boiling point of water. Some boiling points of VOCs are at higher temperatures. At this time, the saturated vapor pressure of these organic waste gases will be higher than 133.3Pa. Under such conditions, they may become volatile organic compounds, which can pollute the air and affect human health. The main components of these volatile organic compounds include: polycyclic aromatic hydrocarbons such as sulfur hydrocarbons, oxygenated hydrocarbons, nitrogen hydrocarbons, halogenated hydrocarbons, hydrocarbons, etc., because of their similar properties, they are easily mixed together and pollute the environment. These VOCs can also threaten the health of human beings, enter the human body in people's breath, and cause damage to human organs. Therefore, in the era of technology, volatile organic waste gas must be treated to control organic waste gas at a certain concentration.
1 analysis of volatile organic waste gas treatment technology
In the high-tech era, the surface of many high-tech products uses paint, plastics, chemicals, and other chemical materials, and many organic substances are used for processing. When these organic substances are used, they will form many volatile organic waste gases. They not only cause physical harm to workers, but also if these gases are arbitrarily discharged into the air without treatment, they will pollute the environment and cause serious harm to human health. For common VOCs treatment technologies, the following are available. Several.
1.1 Treatment of volatile organic waste gas by combustion
The combustion method utilizes the flammability of VOCs. Since they can be burned by themselves, if these organic substances are passed to an incinerator at a certain temperature, these organic substances can be burned. When these organic substances generate CO and HO, They can be discharged into the air. The treatment mechanism of this combustion method is mainly divided into three forms: direct combustion method, thermal combustion method and catalytic combustion method, depending on the combustion temperature and the combustion mode.
1.1.1 Treatment of volatile organic waste gas by direct combustion
Direct combustion is the direct combustion of VOCs by directing VOCs directly into the incinerator to allow VOCs to burn at high temperatures. If the concentration of VOCs is high, they can be burned well in the furnace to generate CO2 and H2O. When the concentration of VOCs is low, the combustion at this time is insufficient, so it is necessary to take certain measures, such as adding auxiliary fuel. The VOCs are completely burned, and finally the VOCs are completely formed into CO2 and H2O, and these CO2 and H2O can be exhausted. The advantage of this method is that due to their low investment cost, the equipment to be prepared is relatively simple and convenient in operation, but the method of using this combustion needs to maintain the condition of high temperature combustion (>1100~C), and at the same time, Under such high temperature conditions, it is easy for the product to form NOx compounds which cause secondary pollutants in the combustion.
1.1.2 Treatment of volatile organic waste gas by catalytic combustion
The catalytic combustion method is a method in which a catalyst is added to a reaction system to completely react VOCs under the action of a catalyst to form CO2 and H2O, and then discharge them into the air. The mechanism of action of this catalyst is mainly to reduce the ignition point of VOCs. There are many types of such catalysts currently used, and these catalysts are mainly noble metal catalysts (such as Pt, Pd) and non-precious metal catalysts (Ti, Fe, Cu, etc.).
Beta and other catalysts have strong selectivity to chlorinated hydrocarbons when they are in contact with VOCs, so that catalysts such as Pt/H-Beta and PdO/H-Beta are susceptible to catalytic decomposition. The study by MACenteno_3 et al. shows that the catalytic combustion method can make the Au/TiOxNy catalyst highly catalyzed by organic substances such as hexane, benzene and propanol. Under this catalysis, the VOCs are completely burned. If the catalytic combustion method is compared with the thermal combustion method, they each have different advantages, but the combustion temperature required for the catalytic combustion method is lower (200 ° C ~ 400 q C), which is its advantage. Since they can be burned at lower temperatures, the generation of secondary secondary pollutants can be avoided and the environment can be protected. However, the catalysts currently used, due to their unstable properties, are easily destroyed by substances containing s, P, As, etc. under certain conditions. Once the activity of the catalyst is destroyed, the catalyst is deactivated, if the catalyst is inactivated, As long as the reaction is carried out, the catalyst needs to be replaced, and this process also requires an expensive cost.
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