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Abstract: In recent years, with the gradual deterioration of the ecological environment, the purification management of developed and cleaned bodies has been increasingly popular among experts and scholars from all walks of life. The management technology of proactive organics is important including acceptance and acceptance technology such as adsorption technology and catalytic oxidation technology. Catalytic oxidation is a more comprehensive technology for treating proactive organics, with advantages such as low energy consumption, no secondary purification, good safety and wide application scope. Through introductions to several aspects such as the treatment technology of volatile organic substances, catalytic oxidation mechanism and volatile organic substance oxidation catalyst, the aim is to promote the progress of volatile organic substance management, especially catalytic oxidation technology.
In today’s society, the increasing destruction of the large environment is in conflict with people’s request for a beautiful body environment. The international and domestic environmental protection laws and regulations and standards are becoming more and more strict, and the management of the large environment is urgent. Commonly used purifiers include particulate matter, sulfur dioxide, nitrogen oxides and Sugar daddyprotein organic matter, etc. Volatile organic compounds (VOCs) refer to organic compounds with boiling points at 50-260°C under normal pressure, and are widely varied, such as alkanes, fragrant syrup, alcohols, aldehydes, ketones and esters. Many VOCs are very toxic, including well-known formaldehyde, benzene, acetone, styrene, etc.
VOCs emission sources include three types: career sources, road sources and industrial sources. With the progress of our society and economic development, the direct emission, the purification of VOCs and the secondary purification of VOCs caused by a series of reactions (such as photochemical smoke) are particularly serious, and the shape of the protection environment is also doubled. In his career, the sources of VOCs include decoration, catering, and daily chemicals; the sources of VOCs are important in road conditions are the tail gas of the motor vehicle; the most types of VOCs emitted in the industry, the widest touch and surface, including petrochemical, printing, spraying and plastic industries.
It can be seen from this that VOCs are widely sourced, and their emissions will not only persecute the large environment and produce photochemical smoke; it will also have an impact on human health and induce a series of diseases. Therefore, urgently needed to find the right VOCsUseful management techniques to reduce VOCs emissions.
1 Management Technology
The management and management technology of VOCs is important. It includes acceptance and acceptance technology and destruction technology. According to the types and concentration of differences, differences can be used. For VOCs with higher concentration, uniform atmosphere and higher prices, they can be accepted and re-applied. Accepting Sugar baby‘s takeover technology mainly includes adsorption technology, reception technology, condensation technology and membrane technology. For VOCs with medium and low concentrations (generally 5,000 mg/m3 or less), air-to-gastric and complex atmosphere and no application value, destruction technology can be used to eliminate it. Importantly, catalytic combustion technology (catalytic oxidation technology), heat incineration technology, biotechnology and other ionic technology.
Adsorption and reception methods refer to the application adsorbent or receiver adsorbent or receiving VOCs in industrial waste gas. In fact, it is just to transfer VOCs from waste gas into the pores or receiving liquid of the adsorbent, not VOCs Discard this, therefore, a kind of incomplete treatment technology is easy to produce secondary purification, and many aspects in the industry limit its application. Condensation technology refers to the application gas dispersion and vapor pressure differences. By reducing the temperature, the VOCs in the waste gas are condensed into liquid and separated, and the VOCs with application value are received and received. The disadvantage of condensation technology is that the application scope is narrower and is generally used for the acceptance and reception of VOCs with higher concentration and single components. Membrane technology refers to the application of membranes as permeability medium, and the application diverges the ability and rate of gases passing through the membrane, and divides the VOCs gases from the waste gas equally. The advantage of membrane technology is that the application scope is wide, but the disadvantage is that the separation is incomplete. The above methods are all physically separated from the cats and are wet. I don’t know how long I have been sleepy here. I look dying VOCs. The management is not thorough and requires secondary treatment.
Heat burning technology is one of the most comprehensive technologies for treating VOCs. It is suitable for VOCs with higher concentrations and has a thorough reaction, but the reaction process is of higher temperature, forming a heat energy waste and nitrogen in the air at high temperatures.It is not difficult to react with oxygen to produce nitrogen oxides, causing secondary purification; biotechnology equipment and duty cycle are relatively large, the processing effect is slow, and there are only one type of VOCs that can be processed; Ion ion technology is a new technology developed in recent years, but its reaction mechanism and reactor design have not been sufficient, so the conversion effect is relatively low, which is difficult to achieve environmentally friendly emission requests.
In the treatment technology of many VOCs, catalytic oxidation technology is one of the most useful ways to completely eliminate VOCs, with features such as simple equipment, low energy consumption, good cancellation consequences and no secondary purification. The catalysts act to reduce the reaction activation energy in the catalytic oxidation reaction, causing the temperature required for catalytic oxidation technology to directly burn. The “Technical Policy for Purification and Control of Developed Organics (VOCs)” which was implemented on May 24, 2013, regards catalytic oxidation technology as a key organic wastewater treatment technology.
2 Introduction to Catalytic oxidation and mechanism
Catalytic oxidation technology is a VOCs treatment technology that has become increasingly widespread in engineering applications in recent years. It is a typical atmosphere-solid catalytic reaction. Its essence is the deep catalytic oxidation reaction of VOCs molecules. The effect of catalytic in the reaction is to adsorb reactor molecules and lower reaction activation. escort can reduce the reaction temperature while accelerating the reaction speed, and water and carbon dioxide, which are naturally friendly to the environment, have no secondary purification.
Depending on the type of catalyst difference, the reaction mechanisms in the general context of precious metal catalysts and non-nutrient metal catalysts are also also similar, including the Langmuir-Hinshelwood reaction mechanism and the MarsvanKrevelen reaction mechanism.
The catalytic oxidation reaction of precious metal catalysts generally follows the Langmuir-Hinshelwood reaction mechanism, as shown in the figure below, which means that before the catalytic reaction process occurs, all reactants have been adsorbed to the catalyst general condition. The general reaction is a speed-controlled step, and its essence is the reaction between the adsorbed particles. The Langmuir-Hinshelwood reaction mechanism is a heterogeneous catalytic reaction of two adsorbed molecules that perform a general reaction, that is, the two reactants are first adsorbed on the solid catalyst, and react on the general situation, and the natural product is then retracted. The reaction rate is proportional to the coverage of the two reactants in the catalytic profile. The reaction process of catalytic oxidation of VOCs by expensive metals is:The sexual component is considered to be in the reduction state, and is affected as the activity of the oxidative reduction general reaction. First, oxygen differentiates into oxygen-free groups at the precious metal active site. At the same time, VOCs gas is adsorbed at the precious metal active site. The oxygen is not restricted by the adsorbed VOCs gas, forming a cleansing carbon dioxide and water, which is attached to the catalyst overview and proceeds to the next reaction process.
The catalytic oxidation reaction of non-expensive metal oxide catalysts generally follows the Mars-van Krevelen reaction mechanism, as shown in the following page, this mechanism is also Escort manila is called an oxidation reduction mechanism, and is actually the reaction between reactors and catalytic lattice oxygen ion during the reaction process. The first is the reaction between the reactor and the lattice oxygen in the catalyst, which generates oxygen vacancy during this process, and at the same time the lattice oxygen is reduced, and then the catalyst is detached from the adsorbed oxygen and supplemented with the oxygen vacancy and is oxidized from the head for regenera TC:
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