Copper Manganese And Cobalt Manganese Oxidessynthesis And Their Application In Catalytic Combustion

Nowadays,there have been extensive efforts to remove volatile organic compounds（VOCs）such as toluene fromenvironment because they are poisonous,smelly and carcinogenic.Catalytic combustion is one of the most effective approaches,in which noble metal catalysts and non-noble oxides catalystshave been applied.Noble metal catalysts,due to the excellent low temperature catalytic activity towards toluene combustion,such as Au,Pd and Pt,are prepared using various procedures.Transitional metal oxides,due to the lower cost,higher stability and better resistance to toxicity compared with the noble metals,such as Cu-Ce oxide and CoOx,have also been widely investigated.Transitional metal oxides’ application in catalytic combustion has become research highlights.Low temperature catalytic activities of the transitional metal oxides catalysts still need to be enhanced.Using copper manganese oxide as precursor,CuMnOx nanorods with diameters of ¹0-20 nm are synthesized by a sodium hydroxide hydrothermal method.It is shown that the BET surface area of Cu:Mn=1:2,500 ℃ calcined oxide have increased from 78.34m2g-1 to 220.98m2g-1 after the 20 h hydrothermal process at 110℃.The sodium hydroxide hydrothermal process also changed cationic distribution and increased the activity of the spinal catalyst markedly by increasing the surface concentration of the higher catalytic activity cations of Cu²⁺,Mn³⁺ and Mn⁴⁺which were essential for catalytic performance.The copper manganese oxide and the nanorods have been investigated with respect to the catalyst activity for the oxidation of toluene.The catalytic activity of CuMn₂-NR has increased significantly compared to the oxides,with a combustion temperature of 210 ℃,lower than the combustion temperature of CuMnOx（250℃）.Cobalt manganese oxide fibers were synthesized by a co-precipitation method.Effects of calcination temperatureand Co/Mn mole ratiowere examined for the catalytic combustion of toluene.SEM,XRD,H₂-TPR and BET specific surface area were investigated.Good linear Arrheniusplotswere obtained over all catalysts.Catalytic performance and activationenergy calculation showed that Co/Mn=1/2,250℃ calcined sample,withABET=188.72m2/g,had the best catalytic activity towards toluene combustion.The catalyst also showed a good stability duringthesteadystateof 24 h,ascribing to itshigherspecificsurfacearea and betterlow-temperaturereducibility.