Rare Earth Doped Manganese-based Composite Oxidation Catalyst For Toluene Combustion And Safety Analysis

Volatile organic compounds?VOCs?are key precursors for the formation of PM2.5 and ozone,easy cause haze,photochemical smog and other serious atmospheric environmental pollution problems,and have physiological toxicity,huge harm to environment and human health.In many degradative VOCs methods,the catalytic combustion technology is regarded as the most effective and promising VOCs purification technology due to its high purification efficiency,low ignition temperature and green environmental protection.Non-noble metal catalyst has the advantages of abundant raw materials,low price,but the catalytic combustion temperature is high,therefore,the development of low-temperature,high-efficient and thermally-stable catalysts has become the focus of catalytic combustion decomposition technology for VOCs.This paper use toluene as a typical pollutant of VOCs,use?-Al₂O₃ as a carrier,Mn is the base element,dope Cu?Ni?Co transition metal elements separately,preparation of Cu-Mn,Ni-Mn,Co-Mn supported metal oxide catalysts by impregnation.The effects of Cu/Mn molar ratio,loading capacity,calcination temperature and impregnation method on catalytic combustion performance of toluene were investigated.The results show that when the Cu/Mn mole ratio of 1:2,15%load,calcination temperature 450?,toluene complete conversion to CO₂ at 260?.Using XRD,BET and TPR and SEM characterization methods of catalysts were analyzed,the results show that the formation of CuMn₂O₄ spinel in the catalyst is beneficial to the reduction of the reduction temperature of the catalyst,and the crystallinity of the active particles is low,making it less likely to agglomerate on the surface of the support,thereby promoting the increase of the activity of the catalyst.And compare the catalytic activity of Cu-Mn,Ni-Mn,and Co-Mn catalysts,the result showed that the catalytic activity of three kinds of catalyst order for Cu-Mn>Ni-Mn>Co-Mn.The XRD results indicate that the doping of Mn with Ni and Co is not easy to form spinel structure,which is the main reason for the decrease catalytic activity.In addition,the rare earth Ce for Cu-Mn doping modification of catalysts,the effect of CeO₂ doping on the catalytic combustion performance of toluene was investigated,and CeO₂ content is between 1%to 7%range,When the CeO₂content is 5%,the catalyst can completely convert toluene to CO₂ at 235°C.XRD showed that with the increase of the content of CeO₂ content,the diffraction peak of CuMn₂O₄ spinel gradually disappeared.It shows that the addition of CeO₂ increases the dispersion of the active components and promotes the contact area between the reactants and the active species.TEM characterization,the active component was highly dispersed on the surface of the carrier,and the mixed crystal phase of CuO,MnO₂ and CeO₂ was found,indicating that the presence of mixed crystals was the main reason for improving the catalytic activity.Safety analysis of system processes through pre-hazard analysis,the results show that the fire and explosion caused by toluene in the process is a major accident,need to strictly control the process conditions,and Combine the factors caused by accidents to formulate relevant protective measures,in order to reduce the probability of accidents and achieve the goal of safe production.