Study On Microwave Assisted Catalytic Oxidation Of Typical VOCs In Exhaust Gas

With the development of social economy,the speed of electronic product renewal is also accelerated,and the output of electronic waste is also increasing.The utilization of electronic waste has become a common understanding of the society.In the process of treatment,two pollution problems are often produced,and VOCs pollution is one of the main pollution.At present,there are many technologies for treating VOCs.Microwave catalytic oxidation technology is the main technology to deal with VOCs pollution due to its low ignition temperature and high efficiency.In addition,microwave heating has many advantages over traditional heating methods,such as selectivity,fast and no hysteresis.Therefore,it is of great significance to catalyze oxidation of VOCs in organic waste gas under microwave field.The LiCoO₂/AC composite oxide catalyst was prepared by impregnation,and toluene was selected as the target pollutant.The catalytic oxidation of toluene in the microwave field was carried out by using silicon carbide and catalyst.The effects of temperature variation on the removal rate of toluene by microwave catalytic oxidation were investigated and the effect of the mixture ratio of silicon carbide and catalyst on the degradation of toluene under microwave conditions was investigated.The optimum bed width and work were investigated.The effect of rate on the removal rate of toluene by microwave catalytic oxidation was investigated.In this paper,a series of characterization of LiCoO₂/AC composite oxide catalysts were carried out,such as X ray diffraction,electron microscope scanning,energy spectrum analysis and specific surface area.In addition,the quartz reaction tube was simulated by CFD,and the distribution of temperature and velocity in the reaction tube of quartz in the process of microwave catalytic oxidation was discussed.The research show that SiC has a good temperature rise curve.When the microwave power is 200W,the microwave reactor can rapidly heat up to more than 300?in 80s.The surface morphology of LiCoO₂/AC composite oxide catalyst prepared by impregnation method was analyzed.It was found that LiCoO₂ was evenly distributed on the surface of activated carbon.The catalyst showed better removal efficiency during the experiment,but the high temperature would cause the surface sintering of the catalyst.The control experiments show that the removal efficiency of pure silicon carbide to toluene is very low,and the catalyst has a certain removal rate for toluene under the traditional heating condition,but the catalyst has a very significant removal rate for toluene under the microwave heating condition.The optimum conditions for microwave catalytic oxidation are microwave power 200W,air velocity 0.06m³.h^-1,bed width 6cm,toluene injection rate30uL.min^-11 and catalyst and silicon carbide mixing ratio of 9:1.Under the optimal conditions,the average removal rate of toluene reached 92.5%after 12 hours of microwave catalytic oxidation.Therefore,the degradation products were analyzed by gas chromatography-mass spectrometry.The results showed that there were benzaldehyde,benzyl alcohol and benzoic acid in the process of toluene degradation,and some small molecules such as butyric acid and acetic acid were produced,and they were not completely mineralized.However,the economic analysis shows that the energy consumption of microwave catalytic oxidation is obviously lower than that of traditional heating,which shows that microwave catalytic oxidation has a great application prospect in the treatment of waste gas.