Preparation Of Monolithic Mn-based Mixed Oxides And Its Catalytic Performance For Toluene

The emission of VOCs from industrial sources in China maintains at a high level at present,although it has a downward trend.Catalytic combustion technology has attracted much attention due to its unique advantages in many industries and fields.As the core of the technology,catalytic materials own more focus,and the development of catalysts with excellent performances will be the most urgent task.Catalytic of VOCs from industrial have been completely degraded at a low temperature（250℃-350℃）and get good application.However,the catalysts face many challenges,such as the lifetime of catalysts is generally less than two years,stability in the catalytic process is poor.Therefore,there is important practical significance and good application prospect about developing industrial catalysts with excellent performances.Some researches show that,compared with the single metal oxide,the composite metal oxides forming solid solution posses more outstanding performances due to the substitution of metal ions,whose gives the catalysts more excellent catalytic activity and improves the comprehensive performance including catalytic activity.In this paper,manganese-cerium solid solution（Mn Ce O_x）is selected as the main component.Preparation parameters are optimized by adjustion of preparation condition,and finally,materials with low-temperature activity(T₉₉≤290℃)and thermal stability（highest operation temperature at 800℃）are obtained.The structure-activity relationship of the catalyst was studied by means of TPR,XPS,SEM and other technologies,thermal stability of the catalyst were especially investigated.The experimental results show that the catalyst prepared by sol-gel method has lower toluene ignition temperature,and appropriate amount of lanthanum has a significant effect on thermal stability.However,the excessive addition of lanthanum has no positive effect on the activity,it even shows a inertia effect on catalytic performances.In addition,in the preparation process of a series of catalysts,sol-gel method shows excellent stability,and it is easy to link with preparation of monolithic catalyst and simplify the preparation process during the later stage.Furthermore,different loading strategies were applied to prepare monolithic catalysts,and the dual effects of loading methods on catalyst loading efficiency and performance were discussed.The actual performance of catalysts under different operating conditions was simulated to get a clear recongization about application boundary condition of catalysts,unsteady conditions,such as various space velocity,temperature and toluene concentration were mainly observed.The results show that the conversion of toluene is dependent on the temperature,space velocity and toluene concentration.With higher temperature,lower space velocity or toluene concentration,the efficiency of catalyst is higher;catalyst perfoumance keeps stable during the long-term regular test（100h）;with wider space velocity(10000～30000h^-1),toluene concentration（100～2000ppm）and temperature（300～550℃）,the simulation test results show that the catalyst has high toluene oxidation efficiency and good stability.