Study On Microwave In-situ Regeneration Of Cu-Mn-Ce/ZSM Adsorbed Toluene And Distribution Of Bed Temperature

Volatile organic compounds(VOCs), as precursor of the PM2.5 and secondary organic aerosol, are becoming an important class of atmospheric pollutants. The BTEX and polycyclic aromatic substances can cause human psychiatric disorders, respiratory diseases, even cancer and other diseases. Among the treatment technologies of volatile organic compounds, adsorption is widely used due to its mature technology, simple operation and high removal rate. However, it will cause secondary pollution at the situation of no recycling of saturated adsorbent. The microwave regeneration methods are studied tremendously because of its fast heating and simple operation. However, the research of bed layer temperature distribution of saturated adsorption catalyst in situ microwave regeneration and regeneration effect on the catalyst is rarely reported, whereas the study on this aspect is crucial to the promotion of technology and practical application.The typical VOCs--toluene was regarded as target adsorbate in this study. The molecular sieve loaded catalyst was prepared by impregnation method. At this situation, the effect of microwave in-situ regeneration of Cu-Mn-Ce/ZSM catalyst adsorbed by toluene on fixed bed was explored. The distribution of temperature on fixed bed was also researched in this article. What’s more, the microwave assisted catalytic oxidation products and degradation pathways of desorption of toluene in the regeneration process were suggested. Besides, characterizations of the catalyst by BET and SEM were investigated in this study, which analyzed the changes of structure and adsorption properties of the catalysts.The research indicates that the regeneration effect of microwave adsorbed by catalyst is excellent under conditions of microwave power 117 W, air flow 0.5m3/h and catalyst 800 g. Toluene desorbed is oxidized onto the surface of the catalyst, which also makes the adsorption capacity recovered simultaneously. The bed temperature decreases slowly from inside to outside in horizontal level, and increases gradually from down to up in vertical level so that the highest temperature can reach 250℃~350℃ at upper sites of the bed. Six adsorption breakthrough curves and catalyst characterization confirm that, sintering and reunion are occurred on the surface of the catalyst in the course of regeneration, at the same time, the special surface area and micropore volume of the catalyst are decreased thus reducing the breakthrough time. However, the catalyst structure stabilizes after two times regeneration, and adsorption breakthrough time is kept at 70 min. The results show that the changes of surface morphology and pore structure are positively correlated with the distribution of bed temperature.