Effect Of Structure And Surface Properties Of Manganese Oxide On The Performance Of Platinum-based CO Oxidation Catalysts

The low-temperature catalytic CO oxidation has been widely researched in the field of heterogeneous catalytic for many years.CO is harmful to the environment and human beings.In order to control the emission of CO,developing CO low temperature oxidation catalysts are also prolonged.Among them,precious metal catalyst is favored by researchers because of its unique low temperature activity.In order to further improve the low temperature activity and stability of catalysts in CO oxidation,the factors that affect the performance of catalysts have been studied in depth,such as adjusting the particle size of precious metals,the nature of the supports and other means.Some supports have the problem insufficient thermal stability,such as FeOOH.In this paper,we proposed the low temperature catalytic oxidation reaction of CO using manganese oxide as the support with relatively stronger thermal stability and supporting platinum nanoparticles through colloidal precipitation method.The prepared catalyst has good CO oxidation activity at low temperature and high thermal stability.The main contents are as follows:1.We compared a series of Pt/MnO₂ catalysts with different structures of manganese oxide supported by 1wt%Pt nanoparticles.It was found that Cryptomelane octahedral molecular sieve（OMS-2）as the support of Pt based catalyst has a good low temperature activity for CO oxidation,and it can complete conversion of CO at room temperature.We compared the performance of Pt/OMS-2 and Pt/α-MnO₂ catalyst in the CO oxidation reaction,the OMS-2 has better activity at low temperature for CO oxidation.For comparation,we prepared MnO₂ supports with the differrnt structure,and found that OMS-2 have more advantages as the support than others structure MnO₂·Moreover,we compared Pt/OMS-2 and Pt/Fe2O3 catalysts,and the results show that Pt/OMS-2 was much better tolerated than Pt/Fe2O3 catalysts.Through a series of characterization,the reason why OMS-2 as support has high activity on the platinum-based catalyst and the reaction mechanism of Pt/OMS-2 catalyst in CO oxidation reaction were studied.2.In order to further improve the performance of the catalyst,researchers have been focusing on the modification of the support in recent years.Based on the work contents of the previous study,we modified the support by two methods:（1）we have mixed Fe³⁺,CO_<sup>2+,Ni²⁺,Cu²⁺,Zn²⁺,Zr4+,Bi³⁺,La³⁺,Ce³⁺,Y³⁺into OMS-2;and（2）mixed FeOOH,Co（OH）2,Ni（OH）2,Mg（OH）2,La（OH）3,Ce（OH）3 with OMS-2.The surface structure of the catalyst supports are changed,and then the performance of the catalysts are changed.The CO activity results showed that the addition of Fe³⁺ and the addition of FeOOH significantly improved the activity of the catalysts in the absence of water.This is related to the incorporation of dopants,which made the interaction between the metal and support was changed,and the catalytic performance of the catalyst also changes.