Preparation Of TiO2 Microsphere-supported Metal Oxide Catalyst And Study On CO Catalytic Oxidation

In the field of heterogeneous catalysis,CO oxidation catalysis is a basic and extensive research.It is of great significance in environmental protection,personal safety and basic research.CO mainly comes from people’s daily life and industrial production.It is produced by the incomplete combustion of some carbon-containing compounds.The elimination of CO has been used in various fields,such as air purification in buildings or vehicles,closed-loop CO₂ lasers,CO detectors,and selective oxidation of CO in reformer gases for fuel cell applications.In addition,CO is often used as a probe molecule to study catalyst structure,adsorption/desorption and reaction mechanism.At present,in CO oxidation reactions,noble metals and non-noble metals are usually used to prepare catalysts.Among the precious metals,Ag is relatively low in cost,and has high activity at low temperatures.Among the non-noble metals,transition metal oxides have great structural differences and changeable oxidation states,which have attracted much attention in redox.But the metal catalyst alone has poor stability and low activity.Therefore,improving the catalytic performance has become one of the major focus.In previous studies,researchers have achieved performance modifications by changing the structure and composition of the catalyst.In this article,we synthesized TiO₂ microspheres with nano-lamellar structure as the carrier,supported transition metal oxides and Ag,and studied the catalytic activity.The details are as follows:1.The experiment adopts hydrothermal synthesis method and uses diethylenetriamine as structure directing agent to synthesize TiO₂ microspheres with nano-sheet structure on the surface.Cobalt acetate,manganese acetate and ferric nitrate were selected as precursors,and the loading amount was 5%.The transition metal oxide catalyst with embedded structure was prepared by the incipient wetness impregnation method.The experimental results show that after calcined at 350 ^oC for4h,the carrier alone also has catalytic activity in CO oxidation.After the transition metal oxide is loaded,the activity is improved.CO could be converted totally at 200^oC by the addition of Co.The order of catalytic activity is:Co O_x/TiO₂>MnO_x/TiO₂>Fe O_x/TiO₂>TiO₂.2.By adjusting the loading of Ag and fixing the loading of cobalt（1 2%）,a silver and cobalt bimetallic catalyst supported on TiO₂microspheres was synthesized.The results show that the catalytic activity of the catalyst could be improved by changing the Ag content.When the Ag loading is 13%,CO could be completely converted at60 ^oC.Strong interaction exists between Ag and cobalt,leading to more oxygen vacancies on the surface,thereby improving the catalytic activity.