Study On Stability Of Ag/ZSM-5-?-Al₂O₃ Mixed Filler Combined With DBD Degradation Of Adsorbed Toluene

Volatile Organic Compounds?VOCs?emissions are increasing year by year,endangering human health.It is also an important precursor of secondary organic particulate matter?SOA?in ozone?O₃?and PM_2.5,and has become one of the atmospheric pollutants that need to be controlled urgently.Non-thermal catalytic technology can degrade VOCs rapidly and efficiently at room temperature and pressure,with less secondary pollution and low investment and operation cost.It is a promising VOCs treatment technology.Among them,catalyst is one of the key factors to ensure the good performance of NTP catalytic technology.At present,there are more extensive studies on single catalyst,but less studies on the optimization and stability of multi-carrier catalyst mixtures.Therefore,this paper makes a systematic study on it.The main conclusions are as follows:The filling method of the mixed carrier ZSM-5 and?-Al₂O₃ not only affects the effect of low temperature plasma degradation of toluene,but also affects the emission of by-products.Compared to stratified filling,a uniformly mixed filling method?M1?is more conducive to the oxidation of toluene,while O₃ emissions are also the least.The mixing ratio?mass ratio?of ZSM-5 and?-Al₂O₃ has an effect on the adsorption and degradation properties of toluene.The adsorption penetration of toluene increases with the increase of the proportion of ZSM-5 in the mixture.The degradation performance?mineralization rate?of toluene decreases with the increase of the ratio of?-Al₂O₃ in the mixture,when ZSM-5 When the mixing ratio with?-Al₂O₃ is 1:2,the mineralization efficiency is the highest.Ag loading of 1%,3%,5%and 10%Ag/ZSM-5-?-Al₂O₃?carrier mixing ratio1:2,Ag loaded on ZSM-5 surface?and NTP degradation of adsorbed toluene were prepared by isovolumetric impregnation method.The results showed that toluene adsorption penetration capacity?8.21 mg/g?and toluene mineralization rate?76%?were the highest when the loading was 5%,and the concentration of by-products N₂O and O₃ gradually decreased with the increase of loading.The NTP degradation experiments of adsorbed toluene with Ag/ZSM-5-?-Al₂O₃ at different relative humidities?20%,40%,60%and 80%?showed that the mineralization rate and by-products of toluene decreased with the increase of humidity.The NTP degradation experiments of adsorbed toluene with Ag/ZSM-5-?-Al₂O₃at different relative humidities?20%,40%,60%and 80%?showed that the mineralization rate and by-products of toluene decreased with the increase of humidity.During the adsorption breakthrough-discharge cycle,with the increase of the number of cycles,the adsorption penetration of toluene gradually decreased.By the end of the cycle,the amount of toluene adsorption penetration decreased by37.4%,and the catalyst showed some degree of deactivation.Characterization of the catalyst showed that the decrease of the adsorbability of the catalyst was mainly due to the surface structure of the catalyst destroyed by the discharge and the blockage of the pore channels,which resulted in the decrease of the specific surface area of the catalyst.The decrease of mineralization and decomposition of by-products of catalysts is mainly attributed to:?1?the accumulation of organic by-products on the surface of catalysts results in carbon deposition,covering the active sites;?2?the decrease of Ag⁺content in the active component.The regeneration efficiency of the deactivated catalyst can be up to 90.9%by oxygen plasma.