Study On Catalytic Oxidation Of Benzene Degradation Performance Of Au-Manganite Catalyst

Increasing amounts of volatile organic pollutants(VOCs)exacerbate the problem of air pollution.This led to more and more countries to take action and set relevant strict standards to limit the emission of VOCs.Therefore,in the face of relevant national environmental standards,a more efficient and environmentally friendly VOCs control technology is required.In this thesis,a fast adsorption method was used to synthesize ultra-stable precious metal supported catalysts;and the structure of the prepared Au-manganese supported The catalyst was characterized by XRD,BET,SEM,GTA,FT-IR and TEM.The chemical composition,surface morphology and catalytic performance of the catalyst have been investigated.The experiment used the prepared catalyst to study the effect of different factors(degradation temperature,reaction flow rate,catalyst addition)on the degradation performance of catalytic oxidation of benzene;orthogonal experiment and response surface optimization were completed,and the exhaust gas composition also passed GC-MS temperament Lianyi conducted an analysis.conclusion as below:(1)SEM results showed that no significant changes were found between the loaded manganese ore and the original ore manganese ore;XRD characterization results showed that the crystal plane spacing(200)of Au after loading was found,and the crystal plane changed original ore.The interplanar spacing of Au-manganese catalysts with other ratios has not changed;the TEM characterization image can find the loaded fine particles,which are in a highly dispersed state;the FT-IR spectrum shows the CO stretching vibration peak of CO₃^2-in the manganese iron ore Because the tetrachloroalloy acid added during the preparation of the supported catalyst disappears in the infrared spectrum of the Au-manganite;different mass ratios have the same effect on the chemical bond of the manganese,and the resulting structure is also the same.The TGA characterization chart found that the experimental temperature range of the supported Au-manganite catalyst is below 650?.At this temperature,except for the decomposition of ferric sulfate and the dehydration reaction of various salts containing crystal water,the main component of manganese salt does not occur.Variety.Quantitative analysis of elements and oxides of manganese ore according to standard methods shows that the content of oxide Mn O is as high as 17.8%;the content of Si O₂in non-metallic elements reaches 54%;it is judged that manganese ore is mainly in the form of silicate,Accounted for at least 60%,followed by sulfate.The BET analysis report shows that the specific surface area S₀ of the 0.2452g Au-manganite catalyst is26.73m²/g;the adsorption well fitted,and the R value reaches 0.9997.Research shows that the catalytic activity of the catalyst is beneficial to the subsequent experiments.(2)In the blank experiment,gaseous benzene did not degrade between 400°C and600°C.At T_(600°C),gaseous benzene began to degrade slightly,and the degradation rate reached the maximum at 680°C-750°C.The reaction temperature When it reaches800°C,gaseous benzene is completely degraded.The reaction flow rate is 0.2 L/min,0.8 L/min,1.5 L/min and 2.0 L/min.The experiment shows that the smaller the reaction flow rate,The more important the reaction process is,the longer the reaction time is.The more effective the degradation.This ultra-low flow of gaseous benzene can effectively degrade benzene in VOCs at low temperatures;however,from the perspective of industrial economy,the low flow rate increases the degradation time,and the electricity consumed by the VOCs passed in a unit of time will follow increase.(3)In the experiment,by adding catalysts with different mass ratios,it is found that the Au/manganite mass ratio of 1:3125 has the best catalytic effect;the initial concentration of 400mg/m³ of benzene is selected for different flow rates and different reaction temperatures.Degradation experiment.The results show that,compared with the blank experiment,the degradation temperature after adding the catalyst is advanced.The original blank degradation temperature needs to reach 600?or higher before weak degradation occurs;after adding the catalyst,the reaction temperature can be degraded at 300?-600?.And the degradation rate can reach 80%when 2g catalyst is added,the flow is 0.2 L/min,and the reaction temperature is 400?,which is enough to show that the catalyst has a better catalytic effect.(4)Mineralization rate is an important index to evaluate whether organic matter is completely mineralized into carbon dioxide and water,Under the condition of low velocity flow at 300?,the mineralization coefficient reaches more than 80%,and increases gradually with the increase of temperature.At 2.0 L/min,the mineralization degree of benzene is much lower than that of benzene,and its catalytic oxidation ability at low temperature is low.Under the condition of low temperature and low velocity,the mineralization can achieve ideal effect.(5)This experiment designs orthogonal and response surface optimization experiments.Orthogonal experiment takes degradation rate,mineralization rate and energy consumption indicators as evaluation indicators.The influence of the evaluation index(degradation rate?V)is:reaction flow>degradation temperature>addition of catalyst,namely:degradation temperature is 600?,reaction flow is 2.0 L/min,and catalyst addition is 2g.The influence of the evaluation index(mineralization rate?)is:reaction flow>degradation temperature>addition of catalyst,namely:degradation temperature is 600?,reaction flow is 0.2 L/min,and catalyst addition is 1.5g.The impact of the evaluation index(energy consumption index E)is:reaction flow>addition of catalyst>degradation temperature,that is,degradation temperature is 500°C,reaction flow is 2.0 L/min,and catalyst addition is 1g.Response surface optimization:Taking the degradation rate?V(Y)as the response value,the effect of each single factor on?V is calculated as reaction flow>degradation temperature>catalyst addition.The optimal process conditions are:degradation temperature 503.6?,reaction flow 0.66 L/min,The added amount of catalyst is 1.11g,and the predicted value of the catalytic oxidation degradation rate of benzene?V(Y)is 125.35 mg/min.(6)The experiment uses gas chromatography GC-MS for qualitative analysis.The ion fragment patterns of unknown compounds appearing in the tail gas have two main fragment ions with charge-to-mass ratios of 64 and 82.Comparing the NIST standard library of catechol mass spectra,the two unknowns are catechol;and no other intermediate products were found.