Synthesis Of Cu-Mn Based Catalysts For Efficient CO Oxidation

The low temperature elimination of CO has important significance in the fields of our industry,energy and life,and the traditional copper-manganese oxide(Hopcalite)catalyst has been used in various industrial fields for its super high activity,which is always related to the preparation methods.Conventional approaches to prepare nanomaterials include hydrothermal method,sol-gel method,impregnation method,etc.These methods cannot accurately control the atomic ratio of the constituent elements,and the synthesis cycle is long and the composition distribution is uneven.In addition,the catalyst prepared by these conventional methods exist in the form of powders,which not only tends to aggregate during the preparation process,but also causes economic and environmental double damage due to the loss of effective components in the recycling process.In this paper,Cu-Mn-0 based catalysts were prepared by spray pyrolysis and micro-arc oxidation-hydrothermal method for efficient CO oxidation.By investigating the influence of different synthesis conditions on the morphology,element composition,distribution,chemical state and phase composition of the catalyst,the reasons responsible for the activity change were revealed,and the CO catalytic oxidation mechanism was proposed,providing some guidance for the in-situ synthesis of other metal oxide catalysts.The related contents are as follows:(1)First,porous hollow sphere hopcalite(copper-manganese oxide)catalyst was prepared by spray pyrolysis method.The influence of synthesis conditions on the catalyst was systematically studied combined with different characterization analyses.It reveals that the catalytic activity of catalyst is closely related to the phase composition and crystallinity,the valence state of copper ions and the specific surface area.CulMn2-550(Cu/Mn=1/2 in the precursor solution,spray pyrolysis temperature is 550 ?)sample exhibited the highest catalytic activity with a complete CO oxidation temperature of 63 ? owing to the formation of CuMn2O4 phase with poor crystallinity and the highest ratio of Cu(II).This work provides a solid basis for the subsequent in-situ growth of CuMnO catalysts.(2)In order to achieve the fixation of the catalyst on substrate and solve the problem of mass loss of powder catalysts,three-dimensional thin nano-sheet Cu-Mn-O catalysts were in-situ grown on the surface of porous TiO2 film fabricated by micro-arc oxidation-hydrothermal combination process.By adjusting the composition of hydrothermal reaction precursor and reaction time,the influence on morphology,element distribution,chemical state and phase composition of the prepared catalyst was investigated,and the immobilization of the powder catalyst was effectively solved.The overall performance of the catalyst was evaluated by using catalytic oxidation of CO as the target reaction.The 12h-CulMn2-300 sample(Cu/Mn = 1/2 in the precursor solution,hydrothermal time is 12 h,and 300 ? annealing for 2 h)can achieve realize a complete CO catalytic oxidation at 150 ?.Under the conditions of long-term placement/higher carrier gas flow rate,the catalyst still maintains excellent catalytic activity,and no crack or powder shedding on the surface was observed.